MEASURING THE PEAK-TO-AVERAGE POWER OF DIGITALLY MODULATED SIGNALS
波形发生器中英文对照外文翻译文献
中英文资料外文翻译THE DESIGN OF ARBITRARY WA VEFORMGENERATORSThe profile generator is can produce the massive standard signals and the user definition signal, and guarantees the high accuracy, high stable, the repeatability and the easy operational electronic instrumentation. The function profile generator has the continual phase transformation, and merits and so on frequency stability, not only may simulate each kind of complex signal, but also may to the frequency, the peak-to-peak value, the phase-shift, the profile carry on the tendency, the prompt control, and can carry on the communication with other instruments, the composition automated test system, therefore widely uses in the automatic control system, the vibration drive, the communication and the instrument measuring appliance domain.As early as in 20's, when the electronic installation just appeared, he appeared.Along with the correspondence and the radar technology development, the 40's appeared has mainly used in testing each kind of receiver the standard signal generating device, caused the signal generating device to become the quantitative analysis from the qualitativeanalysis measuring instrument the metering equipment. Simultaneously also appeared available has tested the pulse electric circuit or serves as the pulse debugger the pulse signal generating device. Quite is complex as a result of the early signal generating device mechanism, the power quite is big, the electric circuit quite is simple, (with digital instrument, oscilloscope compares), therefore develops quite slowly.Only then appeared the first holocrystalline tube signal generating device until 1964. Since the 60's, the signal generating device had the rapid development, appeared the function generator, has swept the frequency signal generating device, the composite signal generator, the program control signal generating device and so on the new type. Each kind of signal generating device performance index also had the large scale enhancement, simultaneously in the simplification mechanism, the miniaturization, multi-purpose and so on various aspects also had the remarkable development. Before the 70's, the signal generating device mainly has two kinds: Sine wave and pulse wave, but the function generator is situated between two kinds, can provide the sine wave, the cosine wave, the square-wave, the triangular wave, the top chord wave and so on several kind of commonly used standard wave patterns, when has other profiles, needs to use the complex electric circuit and the mechanical and electrical union method.This time profile generator uses the simulation electronic technology,moreover simulates the electric circuit which the component constitutes to have the size in a big way, the price expensive, the power loss big and so on the shortcomings, and must have the more complex waveform, then the electric circuit structure is extremely complex. At the same time, the main performance is two prominent questions, one is realizes the output frequency adjustment through the potentiometer adjustment, therefore adjusts very difficultly the frequency some fixture; Two is the pulse dutyfactor cannot adjust. After the 70's, the microprocessor appearance may use the processor, A/D/and D/A, the hardware and the software causes the profile generator the function expansion, has a more complex profile. This time profile generator many by software primarily, the essence is uses the microprocessor to the DAC procedure control, may obtain each kind of simple profile. But at the end of the 90's, appeared several kind of true high performances, the high price function generators, HP Corporation has promoted the model is the HP770S signal imitation installment systems, it had the software by the HP8770A random profile digitization and the HP1776A profile to be composed.HP8770A in fact also only can have 8 profiles, moreover the price is expensive. Soon after, Analogic Corporation has promoted the model is the Data-2020 multi-profile synthesizer, the model which Lecroy Corporation produces is 9100 random profile generators and so on.To the 21st century, along with the integrated circuit technology highspeed development, appeared many kinds of operating frequency to be possible the GHz DDS chip, simultaneously also impelled the function profile generator development, in 2003, Agilent product 33220A could have 17 kind of profiles, the upper frequency may achieve 20M,2005 the year product N6030A could produce reaches as high as the 500MHz frequency, the sampling frequency may reach 1.25GHz.May see by above product, function profile generator development very quick in the last few years, on the international profile generator technological development mainly manifests in following several aspects: (1) quite was in the past narrow and small as a result of the frequency very low application scope, the output wave shape frequency enhancement, enabled the profile generator to apply in the more and more broad domain. The profile generator software development is causing the profile data the input to become even more is more convenient and is easy. The profile generator usual permission with a series of spots, the straight line and the fixed function section stores the profile data the memory. Simultaneously may use one powerful mathematics equation input way, the complex profile may compound become the v=f(t) form by several quite simple formulas the profile equation mathematical expression production.Thus promoted the function profile generator to the random profile generator development, each kind of machine language rapid development also played to the random profile generator software technology the impetusrole. At present may use the visualization programming language (for example Visual Basic, Visual C and so on) compiles the random profile generator the soft kneading board, like this allows from the computer display monitor to input the random profile, realizes the profile input. (2) and VXI resources union. At present, the profile generator and is suitable by the independent table model instrument for the personal computer VXI module which inserted the card as well as recently develops. Because VXI main line gradually mature and to metering equipment high request, needs to use VXI system survey in very many domains to have the complex profile, VXI system resources have provided the obvious superiority, but because develops VXI module the cycle to be long, moreover needs the special VXI engine case the necessary use, causes the profile generator VXI module only to be restricted in the aviation, the military and the national defense and so on the large-scale domain. In the civil aspect, VXI module was inferior by far the table model instrument is more convenient. (3) along with the information technology vigorous development, the table model instrument after walked section of downhill, prospers. But the present new table model instrument shape, has the very big difference with several year ago oneself. These new generation of table model instrument has many kinds of characteristics, may carry out many kinds of functions.Moreover the external dimensions and the price, all reducedcompared to the past similar product one half. As early as in 1978, will announce the highest sampling frequency by American Wavetek Corporation and Japanese East Asia Electric wave Industrial corporation is 5MHz, may form 256 (memory length) the profile data, the vertical resolution is 8bit, mainly uses in vibrating, domain and so on medical service, material first generation of high performance supply oscillators, will pass through is near 30 years development, was following the electronic primary device, the electric circuit, and the production equipment high speed, Gaoji Cheng Hua, the profile generator performance had the rapid enhancement. More and more becomes the operation to be simple output wave shape ability to be more and stronger. The profile operating procedure quality, is by the profile generator control software quality assurance, the edition function increases more much, the profile forms operationally better. The profile generator is the supply oscillator one kind, mainly for was measured the electric circuit provides oneself who needs to know the signal (each kind of profile), then is interested with other measuring appliance survey the parameter. Obviously the supply oscillator applies and experiments in test processing at each kind of experiment, its application is extremely widespread. It is not the metering equipment, but is according to user's request, took the drive source, the simulation each kind of spike, provides for is measured the electric circuit, satisfies the survey or each kind of actual need.At present our country oneself after start to develop the profile generator, and has yielded the encouraging result. But generally speaking, our country profile generator has not formed the true industry. Looked on the present domestic mature product that, many inserts the card for some PC instrument, the independent instrument and VXI system module are very few, and our country at present in profile generator type and performance all with overseas similar product existence big disparity, therefore steps up to this kind of product development to appear imminently.波形发生器的进展波形发生器是能够产生大量的标准信号和用户定义信号，并保证高精度、高稳定性、可重复性和易操作性的电子仪器。
Boonton PMX40 RF Power Meter数据手册说明书
The PMX40 provides design engineers and technicians the utility of traditional benchtop instrument, the flexibility and performance of modern USB RF power sensors, and the simplicity of a multi-touch display built with Boonton award-winning technology.As a benchtop meter, the PMX40 provides a standalone solution for capturing, displaying, and analyzing peak and average RF power in both the time and statistical domains through an intuitive, multi-touch touchscreen display.The PMX40 Power Meter utilizes up to four RTP and CPS families of USB RF power sensors with industry- leading performance and capabilities either independently or for synchronized multi-channel measurements of CW, modulated, and pulsed signals.Providing the ultimate flexibility, the PMX40 sensors can be disconnected and independently used as standalone instruments.Key Features• Capture/display/analyze peak and average power• Frequency range from 4 kHz to 40 GHz• Industry-leading video bandwidth (195 MHz) and rise time (3 ns)• Industry-leading 100,000 measurements per second• Industry-leading 100 ps time resolution• Synchronous multi-channel measurements (up to 4 channels)• Sensors can be used as standalone instruments PMX40 RF Power MeterPulsed ModeAnalysis of fast-rising single pulses or pulses with short pulserepetition intervals (PRIs) requires an instrument with sophisticated trigger and data acquisition capability. Within Pulsed Mode, more than 16 pulse parameters can be measured.Continuous ModeFor simple, intuitive measurements of repetitive waveforms, the PMX40 Continuous Mode of operation provides a numeric display of average, maximum and minimum signal powers.Statistical ModeIn Statistical Mode, the PMX40 plots the Complementary Cumulative Distribution Function (CCDF). The CCDF plot shows the rate of occurrence of a specific crest factor for signals, such as those used in 5G, 4G/LTE, and Wi-Fi applications.PMX40 RF Power Meter – Front PanelConnect up to 4 USB sensors for multi-channel measurements.Multi-touch display with intuitive user interface.One touch to quickly access presets and favorite functions.Sync ports to source or receive triggers for timing and synchronization.Test source to verify sensor operation.The PMX40’s intuitive, multi-touch display enables fast configuration of up to four sensors as well as easy access to measurement and analysis tools, providing a standalone solution for capturing, displaying, and analyzing peak and average RF power in both the time and statistical domains. The meter also incorporates a test source to verify sensor operation.High-Performance and Versatile USB Power Sensors• Real-Time Power Processing™ technology with virtually zero measurement latency • 100,000 measurements per second • 80 dB dynamic range• Synchronized multi-channel measurementsAll RTP Real-Time Power SensorsThe Boonton PMX40 Power Meter utilizes Boonton RTP and CPS families of USB RF power sensors with indus-try leading performance and capabilities. All RTP sensors incorporate the unique Boonton Real-Time Power Processing™ technology, which virtually eliminates gaps in measurement suffered by other power sensors and enables industry best measurement speeds. In terms of RF performance, the RTP5000 series Real-Time Peak Power Sensors are the fastest responding sensors with 3 ns rise times and 195 MHz of video bandwidth. The RTP4000 series Real-Time True Average Power Sensors enable the lowest frequency measurements for diode-based average power measuring sensors and can make accurate measurements virtually independent of signal modulation bandwidth. CPS sensors offer flexible connectivity and performance leadership at anexcellent price point.Real-Time Power Processing™Boonton Real-Time Power Processing 1 dramatically reduces the total cycle time for acquiring and processing power measurement samples. By combining a dedicated acquisition engine, hardware trigger, integrated sample buffer, and a real-time optimized parallel processing architecture, Real-Time Power Processing™ performs most of the sweep processing steps simultaneously, beginning immediately after the trigger instead of waiting for the end of the acquisition cycle.The advantages of the Real-Time Power Processing technique are that key processing steps take place in parallel and keep pace with the signal acquisition. With no added computational overhead to prolong the sweep cycle, the sample buffer cannot overflow. As a result, there is no need to halt acquisition for trace processing. This means gap-free signal acquisition virtually guarantees that intermittent signal phenomena such as transients or dropouts will be reliably captured and analyzed.1RTPP is available within the RTP500 and RTP4000 sensors.Software FeaturesMeasurement Buffer ModeThe RTP series Measurement Buffer Mode is a remote control function that works in conjunction with Real-Time Power Processing to provide only therelevant burst or pulse information, eliminating the need to download and post-process large sample buffers. As a result, users can collect and analyze measurements from a virtually unlimited number of consecutive pulses or events without gaps. A wide variety of parameters can be calculated and plotted, such as duty cycle, pulse repetition rate, pulse width variation, and pulse jitter. In addition, anomalies,such as dropouts, can be identified.Dropouts, such as those shown left, are the sorts of events often missed by conventional power meters due to the acquisition gaps while processing takes place.Example seven pulse waveform.Measurement buffer data returned for waveform in above.Wi-Fi and Wireless Communication Signal AnalysisCharacterization and compliance testing of Wi-Fi and LTE chipsets and devices involves significant challenges for design and test engineers. With multiple-input, multiple-output (MIMO) architectures and channel bandwidths up to 160 MHz, testing is complex, especially when measuring RF power per channel and time alignment between channels. The PMX40 enables packet power measurements to be performed independently on multiple synchronous or asynchronous transmit chains with a common timebase shared among sensors.Use markers to define a portion of the waveform on which to make measurements. “Between Marker” measurements are ideal for monitoring specific portions of a packet over long intervals.Video bandwidth (VBW) describes the ability of a power sensor to track peak (envelope) power. Insufficient VBW will result in errant envelope and average power measurements. The PMX40 offers the widest video bandwidth (195 MHz) making it ideal for measuring 80 MHz, 100 MHz, and 160MHz channels.By comparing the peak-to-average power ratio, or crest factor (CF), of input and output signals of an RF transmission chain, engineers can assess circuit linearity. Additional insight can be provided with the PMX40 statistical mode Complementary Cumulative Distribution Function (CCDF) plot displaying the rate of occurrence of a specific CF. As an amplifier output compresses, the CF will reduce and the CCDF plot will move left.Indication of amplifier output compressionCrest FactorSecondary Surveillance Radar (SSR)Design, verification, troubleshooting and maintenance of secondary surveillanceradar (e.g. IFF-based radar) has never been more demanding.Proper design and operation of SSR systems is critical to the safety and security of aviation. The PMX40 can b e u sed t o easily a nd accurately capture SSR waveforms. Markers enable measurements on specific portions of the waveform.Industry-leading rise time (<3 ns) enables characterization of the most demanding radar signals.Utilize the superior 100 ps time resolution to zoom and uncover signal characteristics that might otherwise be missed.Key Features and Functionality• Data displayed as numerical meter or waveform trace • Statistical analysis with CCDF plot• Multiple marker measurements, including between marker data and marker ratios • Automated measurements; e.g., 16 automated pulse measurements • Export measurement data in .csv or .pdf formats • Up to 8 simultaneous power measurement channels• Simulation mode available to preview functionality when a sensor is not availableKey Features and Functionality• Large numeric readout and/or analog meter display • Zoom and pan through data logging strip chart• Quickly set frequency, aperture (averaging) and offset values all from the main screen• Calculates ratios between sensor measurements • Control up to 8 sensors at once• Simulation mode available to preview functionality when a sensor is not availableSensor SoftwarePower Viewer – Simple and Intuitive Measurement Software(for standalone operation of the CPS2000 Series of sensors)Power Viewer is a complimentary PC-based software package for CPS2008 sensor control, measurement configuration, and analysis. It includes USB drivers, remote control API, firmware updater and virtual instrument application.(for standalone operation of the RTP4000 and RTP5000 series of sensors)Power Analyzer is a complimentary PC-Based software package for RTP5000 and RTP4000 sensor control, measurement configuration, and advanced analysis. It includes USB drivers, remote control API, firmwareupdater and virtual instrument application.Power Analyzer - Advanced Measurement and Analysis SoftwareSensor SpecificationsRTP5006RTP5318 RF Frequency Range50 MHz to 6 GHz50 MHz to 18 GHz Dynamic RangeSpecificationsChannels Up to 4 Sensors RTP5000 SeriesRTP4000 SeriesCPS2000 Series Display5-inch WVGA multi-touch display with intuitive graphical user interfaceDisplay Modes Trace (power vs time)Statistical measurements Meter (numeric display)CCDFAutomatic measurements (pulse, statistical, and markers measurements)Marker Measurements (in Trace View)Markers (vertical cursors)Marker IndependentlyInterval Between MarkersPair of MarkersSettable in time relative to the trigger positionAvg, Min and Max Power at a specified time offsetAvg, Min and Max Power over the defined intervalRatio of power values at each markerPulse Mode – Automatic Measurements Pulse rise-timePulse widthPulse periodPulse duty cyclePulse peakPulse overshootTop level powerEdge delayPulse fall-timePulse off-timePulse repetition frequencyWaveform averagePulse averagePulse droopBottom level powerPulse edge skew between channelsStatistical Mode –Automatic Measurements Peak powerMinimum powerDynamic rangeCrest factor at cursorAverage powerPeak to average ratioPercent at cursorCrest factor at various percentsTrigger Synchronization*ModeSourceInternal Level RangeExternal Level RangeSlopeHold-off, Min Pulse Width, Max Trigger RateAmong RTP Series(internal trig distribution)Normal, Auto, Auto Pk-to-Pk, Free Run Any connected RTP Series sensor (via SMB’s) or rearpanel external trigger -40 dBm to +20 dBm (sensor dependent)±5 volts or TTL+ or -Sensor and timebase dependentTime Base Time Base Resolution, Range, AccuracyTime Base DisplayTrigger Delay RangeTrigger Delay ResolutionSensor dependent Sweeping or Roll Mode Sensor dependent0.02 divisionsSpecifications, ContinuedInputs/Outputs (front panel)USB with SMB trigger port Test Source50 MHz(optional rear panel placement)Inputs/Outputs (rear panel)LANUSB with SMB trigger portWireless Telecom Group Inc. 25 Eastmans Rd Parsippany, NJ United StatesTel: +1 973 386 9696 Fax: +1 973 386 9191 © Copyright 2020 All rights reserved.B/PMX40/0520/ENNote: Specifications, terms and conditions are subject to change without prior notice.PMX40RF Power Meter (includes 2 active channels)OptionsPMX40-4CH PMX40-GPIB PMX40-RTSAdds 2 Active Channels (for a total of 4)GPIB Control (internally installed)Moves Test Source output to the rear panelIncluded AccessoriesInformation Card (provides information on where to download the latest manual, software, utilities)Optional AccessoriesPMX40-RMK PMX40-TCASEFull-width 19” Rack Mount Kit (includes handles & hardware for mounting one or two meters)Transit case, hold the PMX40 and up to 4 sensorsRF Power SensorsCPS2008RTP4006RTP4106RTP4018*RTP4040*RTP5006RTP5318RTP5518RTP5340RTP5540True Average Connected Power Sensor Real-Time True Average Power Sensor Real-Time True Average Power Sensor Real-Time True Average Power Sensor Real-Time True Average Power Sensor Real-Time Peak Power Sensor Real-Time Peak Power Sensor Real-Time Peak Power Sensor Real-Time Peak Power Sensor Real-Time Peak Power Sensor50 MHz to 8 GHz 10 MHz to 6 GHz 4 kHz to 6 GHz 10 MHz to 18 GHz 10 MHz to 40 GHz 50 MHz to 6 GHz 50 MHz to 18 GHz 50 MHz to 18 GHz 50 MHz to 40 GHz 50 MHz to 40 GHzIncluded AccessoriesInformation Card (provides information on where to download the latest manual, software, utilities)0.9 m BNC (m) to SMB (m) cable (RTP sensors)0.9 m SMB (m) to SMB (m) cable (RTP sensors)1.8 m USB A (m) to USB B (m) locking SeaLATCH cable (RTP sensors)1.6 m USB A (m) to USB B (m) cable (CPS sensors)Ordering Information*RTP4018 and RTP4040 are currently in development. Specifications and performance subject to change。
流量测量仪表专业词汇(英文词汇,英文解释)
ac: Alternating current; an electric current that reverses its direction at regularly recurring intervals.Accuracy: The closeness of an indication or reading of a measurement device to the actual value of the quantity being measured. Usually expressed as ± percent of full scale output or reading.Acoustics: The degree of sound. The nature, cause, and phenomena of the vibrations of elastic bodies; which vibrations create compressional waves or wave fronts which are transmitted through various media, such as air, water, wood, steel, etc.Adapter: A mechanism or device for attaching non-mating parts.ADC: Analog-to-Digital Converter: an electronic device which converts analog signals to an equivalent digital form, in either a binary code or a binary-coded-decimal code. When used for dynamic waveforms, the sampling rate must be high to prevent aliasing errors from occurring. Ambient Compensation: The design of an instrument such that changes in ambient temperature do not affect the readings of the instrument.Ambient Conditions: The conditions around the transducer (pressure, temperature, etc.).Ambient Pressure: Pressure of the air surrounding a transducer.Ambient Temperature: The average or mean temperature of the surrounding air which comes in contact with the equipment and instruments under test.Ampere (amp): A unit used to define the rate of flow of electricity (current) in a circuit; units are one coulomb (6.28 x 1018 electronics) per second.Amplitude: A measurement of the distance from the highest to the lowest excursion of motion, as in the case of mechanical body in oscillation or the peak-to-peak swing of an electrical waveform. Analog Output: A voltage or current signal that is a continuous function of the measured parameter.Analog-to-Digital Converter (A/D or ADC): A device or circuit that outputs a binary number corresponding to an analog signal level at the input.ATC: Automatic temperature compensation.Background Noise: The total noise floor from all sources of interference in a measurement system, independent of the presence of a data signal.Bandwidth: A symmetrical region around the set point in which proportional control occurs.Baud: A unit of data transmission speed equal to the number of bits (or signal events) per second; 300 baud = 300 bits per second.Bearing: A part which supports a journal and in which a journal revolves.Beta Ratio: The ratio of the diameter of a pipeline constriction to the unconstricted pipe diameter. BNC: A quick disconnect electrical connector used to inter-connect and/or terminate coaxial cables. BTU: British thermal units. The quantity of thermal energy required to raise one pound of water at its maximum density, 1 degree F. One BTU is equivalent to .293 watt hours, or 252 calories. One kilowatt hour is equivalent to 3412 BTU.Bus: Parallel lines used to transfer signals between devices or components. Computers are often described by their bus structure (i.e., S-100, IBM PC).Calibration: The process of adjusting an instrument so that its reading can be correlated to the actual value being measured.Cavitation: The boiling of a liquid caused by a decrease in pressure rather than an increase in temperature.CE approval: CE marking is a declaration by the manufacturer that the product meets all the appropriate provisions of the relevant legislation implementing certain European Directives. The initials "CE" do not stand for any specific words but are a declaration by the manufacturer that his product meets the requirements of the applicable European Directive(s). Portaflow 330, 220A, 220B models manufactured in accordance with the following Directives and Standards: Directive2004/108/EC, Directive 2006/95/EC. BS EN 61010-1:2001, BS EN61326-1:2006, BS EN613626-2:2006.Centre of Gravity (Mass Centre): The centre of gravity of a body is that point in the body through which passes the resultant of weights of its component particles for all orientations of the body with respect to a uniform gravitational field.CFM: The volumetric flow rate of a liquid or gas in cubic feet per minute.Closeness of Control: Total temperature variation from a desired set point of system. Expressed as "closeness of control" is ±2°C or a system bandwidth with 4°C, also referred to as amplitude of deviation.Colour Code: The ANSI established colour code for thermocouple wires in the negative lead is always red. Colour Code for base metal thermocouples is yellow for Type K, black for Type J, purple for Type E and blue for Type T.Communication: Transmission and reception of data among data processing equipment and related peripherals.Compensated Connector: A connector made of thermocouple alloys used to connect thermocouple probes and wires.Compensation: An addition of specific materials or devices to counteract a known error.Confidence Level: The range (with a specified value of uncertainty, usually expressed in percent) within which the true value of a measured quantity exists.Connection Head: An enclosure attached to the end of a thermocouple which can be cast iron, aluminium or plastic within which the electrical connections are made.Convection: 1. The circulatory motion that occurs in a fluid at a non-uniform temperature owing to the variation of its density and the action of gravity. 2. The transfer of heat by this automatic circulation of fluid.CPS: Cycles per second; the rate or number of periodic events in one second, expressed in Hertz (Hz).Critical Damping: Critical damping is the smallest amount of damping at which a given system is able to respond to a step function without overshoot.Critical Speed: The rotational speed of the rotor or rotating element at which resonance occurs in the system.Damping: The reduction of vibratory movement through dissipation of energy. Types include viscous, coulomb, and solid.dB (Decibel): 20 times the log to the base 10 of the ratio of two voltages. Every 20 dBs correspond to a voltage ratio of 10, every 10 dBs to a voltage ratio of 3.162. For instance, a CMR of 120 dB provides voltage noise rejection of 1,000,000/1. An NMR of 70 dB provides voltage noise rejection of 3,162/1.DC: Direct current; an electric current flowing in one direction only and substantially constant in value.Dead Volume: The volume of the pressure port of a transducer at room temperature and ambient barometric pressure.Default: The value(s) or option(s) that are assumed during operation when not specified.Degree: An incremental value in the temperature scale, i.e., there are 100 degrees between the ice point and the boiling point of water in the Celsius scale and 180°F between the same two points in the Fahrenheit scale.Density: Mass per unit of volume of a substance. I.E.: grams/cu.cm. or pounds/cu.ft.Deviation: The difference between the value of the controlled variable and the value at which it is being controlled.Differential: For an on/off controller, it refers to the temperature difference between the temperature at which the controller turns heat off and the temperature at which the heat is turned back on. It is expressed in degrees.Digital Output: An output signal which represents the size of an input in the form of a series of discrete quantities.Digital-to-Analog Converter (D/A or DAC): A device or circuit to convert a digital value to an analog signal level.DIN (Deutsche Industrial Norm): A set of German standards recognized throughout the world. The 1/8 DIN standard for panel meters specifies an outer bezel dimension of 96 x 48 mm and a panel cutout of 92 x 45 mm.Doppler Technology: An acoustic pulse is reflected back to the sensor from particles or gases in the flowing liquid. The flow rate of any fluid can be measured as long as it contains air bubbles or solids. It is ideal for wastewater, slurries, sludge and most chemicals, acids, caustics and lubrication fluids.Drift: A change of a reading or a set point value over long periods due to several factors including change in ambient temperature, time, and line voltage.Duplex: Pertaining to simultaneous two-way independent data communication transmission in both direction. Same as "full duplex".Echo: To reflect received data to the sender. For example, keys depressed on a keyboard are usually echoed as characters displayed on the screen.Electrical Interference: Electrical noise induced upon the signal wires that obscures the wanted information signal.EMI: Electromagnetic interference.Emissivity: The ratio of energy emitted by an object to the energy emitted by a blackbody at the same temperature. The emissivity of an object depends upon its material and surface texture; a polished metal surface can have an emissivity around 0.2 and a piece of wood can have an emissivity around 0.95.End Point (Potentiometric): The apparent equivalence point of a titration at which a relatively large potential change is observed.Environmental Conditions: All conditions in which a transducer may be exposed during shipping, storage, handling, and operation.Error: The difference between the value indicated by the transducer and the true value of the measurand being sensed.Explosion-proof Enclosure: An enclosure that can withstand an explosion of gases within it and prevent the explosion of gases surrounding it due to sparks, flashes or the explosion of the container itself, and maintain an external temperature which will not ignite the surrounding gases.Exposed Junction: A form of construction of a thermocouple probe where the hot or measuring junction protrudes beyond the sheath material so as to be fully exposed to the medium being measured. This form of construction usually gives the fastest response time.Fahrenheit: A temperature scale defined by 32° at the ice point and 212° at the boiling point ofwater at sea level.Ferrule: A compressible tubular fitting that is compressed onto a probe inside a compression fitting to form a gas-tight seal.Field Balancing Equipment: An assembly of measuring instruments for performing balancing operations on assembled machinery which is not mounted in a balancing machine.Field of View: A volume in space defined by an angular cone extending from the focal plane of an instrument.File: A set of related records or data treated as a unit.Flow Rate: Actual speed or velocity of fluid movement.Flow: Travel of liquids in response to a force (i.e. pressure or gravity).FPM: Flow velocity in feet per minute.FPS: Flow velocity in feet per second.Freezing Point: The temperature at which the substance goes from the liquid phase to the solid phase.Frequency Output: An output in the form of frequency which varies as a function of the applied input.Frequency, Natural: The frequency of free (not forced) oscillations of the sensing element of a fully assembled transducer.Frequency: The number of cycles over a specified time period over which an event occurs. The reciprocal is called the period.Full Scale Output: The algebraic difference between the minimum output and maximum output. GPH: Volumetric flow rate in gallons per hour.GPM: Volumetric flow rate in gallons per minute.Ground: 1. The electrical neutral line having the same potential as the surrounding earth. 2. The negative side of DC power supply. 3. Reference point for an electrical system.Grounded Junction: A form of construction of a thermocouple probe where the hot or measuring junction is in electrical contact with the sheath material so that the sheath and thermocouple will have the same electrical potential.Handshake: An interface procedure that is based on status/data signals that assure orderly data transfer as opposed to asynchronous exchange.Hardware: The electrical, mechanical and electromechanical equipment and parts associated with acomputing system,Heat Sink: 1. Thermodynamic. A body which can absorb thermal energy. 2. Practical. A finned piece of metal used to dissipate the heat of solid state components mounted on it.Heat Transfer: The process of thermal energy flowing from a body of high energy to a body of low energy. Means of transfer are: conduction; the two bodies contact. Convection; a form of conduction where the two bodies in contact are of different phases, i.e. solid and gas. Radiation: all bodies emit infrared radiation.Heat Treating: A process for treating metals where heating to a specific temperature and cooling at a specific rate changes the properties of the metal.Heat: Thermal energy. Heat is expressed in units of calories or BTU's.Hertz (Hz): Units in which frequency is expressed. Synonymous with cycles per second.ID: Inside diameterInfrared: An area in the electromagnetic spectrum extending beyond red light from 760 nanometers to 1000 microns (106 nm). It is the form of radiation used for making non-contact temperature measurements.Insulated Junction: See Ungrounded JunctionInsulation Resistance: The resistance measured between two insulated points on a transducer when a specific dc voltage is applied at room temperature.Interchangeability Error: A measurement error that can occur if two or more probes are used to make the same measurement. It is caused by a slight variation in characteristics of different probes. Interface: The means by which two systems or devices are connected and interact with each other. Intrinsically Safe: An instrument which will not produce any spark or thermal effects under normal or abnormal.IP Rating: (or "Ingress Protection") ratings are defined in international standard EN 60529 (British BS EN 60529:1992, European IEC 60509:1989). They are used to define levels of sealing effectiveness of electrical enclosures against intrusion from foreign bodies (tools, dirt etc) and moisture.IP66: First digit is the intrusion protection, in this case 6 is totally dust tight. Second digit is moisture protection, in this instance protection against string water jets and waves.IP67: Total dust ingress protection and protected against temporary immersion between 15cm and 1m depth.Isolation: The reduction of the capacity of a system to respond to an external force by use of resilient isolating materials.Joule: The basic unit of thermal energy.Junction: The point in a thermocouple where the two dissimilar metals are joined.Kelvin: Symbol K. The unit of absolute or thermodynamic temperature scale based upon the Celsius scale with 100 units between the ice point and boiling point of water. 0°C = 273.15K (there is no degree (°) symbol used with the Kelvin scale).Kilowatt (kw): Equivalent to 1000 watts.Kilowatt Hour (kwh): 1000 watthours. Kilovolt amperes (kva): 1000 volt amps.Kinetic Energy: Energy associated with mass in motion, i.e., 1/2 rV2 where r is the density of the moving mass and V is its velocity.Laminar Flow: Streamlined flow of a fluid where viscous forces are more significant than inertial forces, generally below a Reynolds number of 2000.Leakage Rate: The maximum rate at which a fluid is permitted or determined to leak through a seal. The type of fluid, the differential Limits of Error: A tolerance band for the thermal electric response of thermocouple wire expressed in degrees or percentage defined by ANSI specification MC-96.1 (1975).Life Cycle: The minimum number of pressure cycles the transducer can endure and still remain within a specified tolerance.Linearity: The closeness of a calibration curve to a specified straight line. Linearity is expressed as the maximum deviation of any calibration point on a specified straight line during any one calibration cycle.Load Impedance: The impedance presented to the output terminals of a transducer by the associated external circuitry.Load: The electrical demand of a process expressed as power (watts), current (amps) or resistance (ohms).M: Mega; one million. When referring to memory capacity, two to the twentieth power (1,048,576 in decimal notation).Mass Flow Rate: Volumetric flowrate times density, i.e. pounds per hour or kilograms per minute. Maximum Operating Temperature: The maximum temperature at which an instrument or sensor can be safely operated.Maximum Power Rating: The maximum power in watts that a device can safely handle.Mean Temperature: The average of the maximum and minimum temperature of a process equilibrium.Method of Correction: A procedure whereby the mass distribution of a rotor is adjusted to reduce unbalance, or vibration due to unbalance, to an acceptable value. Corrections are usually made byadding material to, or removing it from, the rotor.Mica: A transparent mineral used as window material in high-temperature ovens.Microamp: One millionth of an ampere, 10-6 amps, µA.Micron: One millionth of a meter, 10-6 meters.Mil: One thousandth of an inch (.001").Millimeter: One thousandth of a meter, symbol mm.NB: Nominal Bore.NEMA-4: A standard from the National Electrical Manufacturers Association, which defines enclosures intended for indoor or outdoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, and hose-directed water.NEMA-7: A standard from the National Electrical Manufacturers Association, which defines explosion-proof enclosures for use in locations classified as Class I, Groups A, B, C or D, as specified in the National Electrical Code.NEMA-12: A standard from the National Electrical Manufacturers Association, which defines enclosures with protection against dirt, dust, splashes by non-corrosive liquids, and salt spray. Noise: An unwanted electrical interference on the signal wires.O.D.: Outside diameter.Offset: The difference in temperature between the set point and the actual process temperature. Also, referred to as droop.Output Impedance: The resistance as measured on the output terminals of a pressure transducer. Output Noise: The RMS, peak-to-peak (as specified) ac component of a transducer's dc output in the absence of a measurand variation.Output: The electrical signal which is produced by an applied input to the transducer.Parity: A technique for testing transmitting data. Typically, a binary digit is added to the data to make the sum of all the digits of the binary data either always even (even parity) or always odd (odd parity).Phase: A time based relationship between a periodic function and a reference. In electricity, it is expressed in angular degrees to describe the voltage or current relationship of two alternating waveforms.Polypropylene: A polymer of propylene used as a thermoplastic moulding material. Doesn't soak up water, making it ideal for uses where it will be constantly subject to moisture.PortaGraph Software: Portagraph II is a software application specifically written for use with Micronics flowmeters which simplifies the downloading and viewing of the instum ent’s logged data. Data may also be viewed in text format or exported to Excel for more detailed analysis. Also allows real time monitoring, where measured data is automatically captured sample by sample and displayed in either graph or data table format. Data logged in one set of units can quickly be converted to another set if required.Positive Temperature Coefficient: An increase in resistance due to an increase in temperature.Potential Energy: Energy related to the position or height above a place to which fluid could possibly flow.Power Supply: A separate unit or part of a circuit that supplies power to the rest of the circuit or to a system.PPM: Abbreviation for "parts per million," sometimes used to express temperature coefficients. For instance, 100 ppm is identical to 0.01%.Primary Device: Part of a flowmeter which is mounted internally or externally to the fluid conduit and produces a signal corresponding to the flowrate and from which the flow may be determined.Probe: A generic term that is used to describe many types of temperature sensors.Process Meter: A panel meter with sizeable zero and span adjustment capabilities, which can be scaled for readout in engineering units for signals such as 4-20 mA, 10-50 mA and 1-5 V.Range: Those values over which a transducer is intended to measure, specified by its upper and lower limits.Rangeability: The ratio of the maximum flowrate to the minimum flowrate of a meter.Rankine (°R): An absolute temperature scale based upon the Fahrenheit scale with 180° between the ice point and boiling point of water. 459.67°R = 0°F.Real Time: The time interval over which the system temperature is sampled for the derivative function.Reference Mark: Any diagnostic point or mark which can be used to relate a position during rotation of a part to its location when stopped.Relay (Mechanical): An electromechanical device that completes or interrupts a circuit by physically moving electrical contacts into contact with each other.Relay (Solid State): A solid state switching device which completes or interrupts a circuit electrically with no moving parts.Remote: Not hard-wired; communicating via switched lines, such as telephone lines. Usually refers to peripheral devices that are located a site away from the CPU.Repeatability: The ability of a transducer to reproduce output readings when the same measured value is applied to it consecutively, under the same conditions, and in the same direction.Repeatability is expressed as the maximum difference between output readings.Residual (Final) Unbalance: Residual unbalance is that unbalance of any kind that remains after balancing.Resistance: The resistance to the flow of electric current measured in ohms (1/2) for a conductor. Resistance is function of diameter, resistivity (an intrinsic property of the material) and length.Reynolds Number: The ratio of inertial and viscous forces in a fluid defined by the formula Re = rVD/µ, where: r = Density of fluid, µ = Viscosity in centipoise (CP), V = Velocity, and D = Inside diameter of pipe.RFI: Radio frequency interference.Secondary Device: A part of the flowmeter which receives a signal proportional to the flowrate, from the primary device, and displays, records and/or transmits the signal.Sensing Element: That part of the transducer which reacts directly in response to the input.Sensitivity Shift: A change in slope of the calibration curve due to a change in sensitivity.Sensitivity: The minimum change in input signal to which an instrument can respond.SI: System Internationale. The name given to the standard metric system of units.Signal: An electrical transmittance (either input or output) that conveys information.Spectrum: The resolving of overall vibration into amplitude components as a function of frequency.Stability: The quality of an instrument or sensor to maintain a consistent output when a constant input is applied.Temperature Error: The maximum change in output, at any measure and value within the specified range, when the transducer temperature is changed from room temperature to specified temperature extremes.Temperature Range, Compensated: The range of ambient temperatures within which all tolerances specified for Thermal Zero Shift and Thermal Sensitivity Shift are applicable (temperature error).Thermal Coefficient of Resistance: The change in resistance of a semiconductor per unit change in temperature over a specific range of temperature.Thermal Conductivity: The property of a material to conduct heat in the form of thermal energy.Thermocouple: The junction of two dissimilar metals which has a voltage output proportional to the difference in temperature between the hot junction and the lead wires (cold junction) Thomson Effect: When current flows through a conductor within a thermal gradient, a reversible absorption or evolution of heat will occur in the conductor at the gradient boundaries.Time of Flight (TOF): describes a variety of methods that measure the time that it takes for an object, particle or acoustic, electromagnetic or other wave to travel a distance through a medium. This measurement can be used for a time standard as a way to measure velocity or path length through a given medium, or as a way to learn about the particle or medium (such as composition or flow rate).Transducer Vibration: Generally, any device which converts movement, either shock or steady state vibration, into an electrical signal proportional to the movement; a sensor.Transducer: A device (or medium) that converts energy from one form to another. The term is generally applied to devices that take physical phenomenon (pressure, temperature, humidity, flow, etc.) and convert it to an electrical signal.Transient Vibration: A temporary vibration or movement of a mechanical system.Transit Time: A typical transit-time flow measurement system utilizes two ultrasonic transducers that function as both ultrasonic transmitter and receiver. The flow meter operates by alternately transmitting and receiving a burst of sound energy between the two transducers and measuring the transit time that it takes for sound to travel between the two transducers. The difference in the transit time measured is directly and exactly related to the velocity of the liquid in the pipe.Transitional Flow: Flow between laminar and turbulent flow, usually between a pipe Reynolds number of 2000 and 4000.Transmitter (Two-Wire): 1. A device which is used to transmit data from a sensor via a two-wire current loop. The loop has an external power supply and the transmitter acts as a variable resistor with respect to its input signal. 2. A device which translates the low level output of a sensor or transducer to a higher level signal suitable for transmission to a site where it can be further processed.Turbulent Flow: When forces due to inertia are more significant than forces due to viscosity. This typically occurs with a Reynolds number in excess of 4000.Union: A form of pipe fitting where two extension pipes are joined at a separable coupling.Vacuum: Any pressure less than atmospheric pressure.Velocity: The time rate of change of displacement; dx/dt.Vibration Error Band: The error recorded in output of a transducer when subjected to a given set of amplitudes and frequencies.Vibration Error: The maximum change in output of a transducer when a specific amplitude and range of frequencies are applied to a specific axis at room temperature.Viscosity: The inherent resistance of a substance to flow.Volt: The (electrical) potential difference between two points in a circuit. The fundamental unit is derived as work per unit charge-(V = W/Q). One volt is the potential difference required to moveone coulomb of charge between two points in a circuit while using one joule of energy.Voltage: An electrical potential which can be measured in volts.Volume Flow Rate: Calculated using the area of the full closed conduit and the average fluid velocity in the form, Q = V x A, to arrive at the total volume quantity of flow. Q = volumetric flowrate, V = average fluid velocity, and A = cross sectional area of the pipe.Watt Density: The watts emanating from each square inch of heated surface area of a heater. Expressed in units of watts per square inch.Working Standard: A standard of unit measurement calibrated from either a primary or secondary standard which is used to calibrate other devices or make comparison measurements.Zero Offset: 1. The difference expressed in degrees between true zero and an indication given by a measuring instrument. 2. See Zero Suppression。
固化剂硫醇当量的测定方法
固化剂硫醇当量的测定方法Determining the equivalent amount of thiol in a curing agent is crucial in various industries such as pharmaceuticals, cosmetics, and food. The thiol equivalent is a measure of the reactive functionality of the curing agent, and it is essential to accurately determine this value for quality control and formulation purposes. There are several methods for determining the thiol equivalent of a curing agent, and each method has its advantages and limitations.确定固化剂硫醇当量在制药、化妆品和食品等各个行业中非常关键。
硫醇当量是固化剂反应功能性的衡量标准，准确测定这个数值对于质量控制和配方设计至关重要。
有几种方法可以确定固化剂硫醇当量，每种方法都有其优点和局限性。
One common method for determining the thiol equivalent of a curing agent is titration with a standard solution of a known concentration. In this method, a known amount of the curing agent is reacted with a standard solution of a chemical reagent, and the amount of reagent consumed is used to calculate the thiol equivalent. This method is relatively simple and can provide accurateresults, but it requires careful handling of the reagents and precise measurements.一种常用的确定固化剂硫醇当量的方法是使用已知浓度的标准溶液进行滴定。
Doherty功率放大器(英文)
The Doherty Power Amplifier The current wireless communication systems have made significant progress toward increased bandwidth and number of carriers for high-data-rate applications. Memory effects, however, make it very difficult to design a high-power amplifier with a wide instantaneous bandwidth. In addition to bandwidth concerns, the instantaneous transmit powers of the wireless communication systems, such as CDMA-2000, wide-band code division multiple access (WCDMA), orthogonal frequency division multiplexity (OFDM) and so on, vary widely and rapidly, carrying high peak-to-average ratio (PAR) signals. The base station power amplifiers for the systems require a high linearity to amplify the high PAR signal source without distortion. To satisfy linearity requirements, the power amplifiers are usually biased at class A or AB mode and must operate at a large amount of back-off from the peak output power. Another requirement of the base station power amplifier for the modern wireless communication systems is high efficiency. As the communication systems are reduced in both size and cost, the cooling system should be simple and small, requiring a power amplifier with high efficiency. Because the base station power amplifiers have a low efficiency due to the back-off operation, efficiency enhancement techniques become very important. The design technique of the base stationpower amplifiers with high efficiency and linearity across a wide instantaneous bandwidth has become a hot issue.In this article, we show that the Doherty amplifier iscapable of delivering the stringent requirements of the base station power amplifiers. We explain the operation principles, including both linearity and efficiency improvements, and the basic circuit configuration of the amplifier. Advanced design methods to operate across wide bandwidth and improve the linearity are also described. For verification, the Doherty amplifier is implemented using laterally diffused metal oxide semiconductor (LDMOS) transistors and measured using a WCDMA 4FA signal. These results show that the Doherty amplifier is a promising candidate for base station power amplifiers with wide bandwidth, high efficiency, and linearity.Doherty Amplifier OperationFigure1. (a)Operational diagram of the Doherty amplifier.(b) Fundamental currents. (c) Load impedances.The Doherty amplifier was first proposed by W.H. Doherty in 1936. The original Doherty amplifier consisted of two tube amplifiers and an impedance inverting network. The efficiency of an RF power amplifier is increased using the RF Doherty amplifier technique, as described in detail in . This amplifier consisted of a carrier amplifier and a peaking amplifier. The output load is connected to the carrier amplifier through an impedance inverter (a quarter-wave transmission line) and directly to the peaking amplifier. Figure 1(a) shows an operational diagram toanalyze the Doherty amplifier circuit. Two current sources represent the amplifiers. It is assumed that each current source is linearly proportional to the input voltage signal, operating as a class AB or class B amplifier with harmonic short circuits after it is turned on, and the efficiency analysis can be carried out using the fundamental and dc components only. As shown in Figure 1(b), the peaking amplifier turns on at one-half the maximum input voltage.The Doherty amplifier technique is based on the load impedance change of each amplifier, referred to as load modulation, according to the input power level. Figure 1(b) shows the fundamental currents from the amplifiers. The load impedances of two amplifiers are given bywhere ZL is the load impedance of the Doherty amplifier; IC and IP represent the fundamental currents of the carrier and peaking amplifiers, respectively; and ZC and ZP are the output load impedances of the carrier and peaking amplifiers, respectively, and are depicted in Figure 1(c).In the low-power region (0 ∼Vin, max/2), the peaking amplifier remains in the cut-off state, and the load impedance of the carrier amplifier is two times larger than that of the conventional amplifier. Thus, the carrier amplifier reaches the saturationstate at the input voltage(Vin, max)/2 since the maximum fundamental current swing is half and the maximum voltage swing reaches Vdc. As a result, the maximum power level is half of the carrier amplifier’s allowable power level (a quarter of the total maximum power or 6 dB down from the total maximum power), and the efficiency of the amplifier is equal to the maximum efficiency of the carrier amplifier as shown in Figure 2.In the high-power region (Vin, max/2 ∼Vin, max), where the peaking amplifier is conducting, the current level of the peaking amplifier plays an important role in determining the load modulation of the Doherty amplifier [see (1) and (2)]. Assuming that gm of the peaking amplifier is twice as large as that of the carrier amplifier, the current and voltage swings of the peaking amplifier increase in proportion to the input voltage level and the voltage swing reaches the maximum voltage swing of Vdc only at the maximum input voltage. The load impedance of the carrier amplifier varies from 2Zopt to Zopt, and the peaking amplifier varies from ∞ to Zopt according to the input voltage level as shown in Figure 1(c). The efficiency of the Doherty amplifier at the maximum input voltage is equal to the maximum efficiency of the amplifiers. When the peaking amplifier is the same size as the carrier amplifier, which is normally the case, gm of the two amplifiers are identical and the peaking amplifier can not be fullyturned on, so the powerperformance is degraded [4].From thebasic operation principle, we have exploredthe Doherty amplifier, which provides higher efficiency over whole power ranges compared to the conventional class AB amplifiers. The resulting Doherty amplifiercan solve the problem of maintaining a high efficiencyfor a large PAR signal.Linearity of the Doherty AmplifierThe linearity of the Doherty amplifier is more complicated than that of a class AB amplifier. The class AB biased carrier amplifier has a load impedance at the low power level that is twice as large and the high impedance of the carrier amplifier compensates the low gain characteristic due to the input power division. At high power levels, the two amplifiers generate full power using normal load impedances, equalizing the power gain. Additionally, in the low-power region, the linearity of the amplifier is entirely determined by the carrier amplifier. Therefore, the carrier amplifier should be highly linear even though the load impedance is highAt a high power level, linearity of the amplifier is improved by the harmonic cancellation from the two amplifiers using appropriate gate biases. Figure 3 shows the third-order harmonic generation coefficient gm3 of an LDMOS transistor and the bias points of the two amplifiers. In terms of gain characteristics of each amplifier, a late gain expansion of the class C biased peaking amplifier compensates the gain compression of the classAB carrier amplifier. Thus, the Doherty amplifier, which is based on the load modulation technique, is capable of delivering more linear output power than a conventional class AB power amplifier. The third-order intermodulation (IM3) level from the carrier amplifier increases and the phase of the IM3 decreases because the gain of the carrier amplifier is compressed. In contrast, when the gain of the peaking amplifier is expanded, both the IM3 level and phase increase. To cancel out the IM3s from the two amplifiers, the components must be 180◦out of phase with the same amplitudes. Therefore, the peaking amplifier should be designed appropriately to cancel the harmonics of the carrier amplifier..The Circuit Configuration of Doherty AmplifierFigure 4 shows a schematic diagram of the fully matched microwave Doherty amplifier with offset transmission lines at the output circuits [5]. The carrier and peaking amplifiers have input/output matching circuits, which transform from the input impedances of the devices to 50 and from the optimum load impedance Zopt of the devices to 50 , respectively. The additional offset transmission lines with characteristic impedance of 50 are connected after the matching circuits of the carrier and peaking amplifiers. In the low-power region, the phase adjustments of the offset lines cause the peaking amplifier to be open-circuited and the characteristic load impedance of the carrier amplifier is doubled to 2Ro by a quarterwave impedancetransformer. This is illustrated in Figure 5(a) and (b). The offset line of the carrier amplifier varies from Zopt to 2Zopt for the proper load modulation as shown in Figure 5(a). Figure 5(b) illustrates that the offset line of the peaking amplifier adjusts to the high impedance so that it prevents power leakage. Figure 5(c) shows the appropriate transformations on a Smith chart to determine the offset line length of each amplifier. The lines do not affect the overall matching condition and load modulation because they are matched to the characteristic impedance of 50 . The Doherty output combining circuit consists of a quarter-wave transmission line with the characteristic impedance of 50 and a quarter-wave transmission line that transforms from 50 to 25 to determine the load impedance of the output combining circuit. Aphase delay line is needed at the input of the peaking amplifier to adjust the same delay between the carrier and peaking amplifiers [6].The Doherty amplifier consists of a class AB biased carrier amplifier and a class C biased peaking amplifier. Due to the different biasing, the RF current from the amplifiersare different depending on the input drive level. The asymmetric powers are combined by the Doherty operation through a quarter-wave impedance converter.Advanced Design Methods for the Doherty AmplifierThe fundamental operation principles of a Doherty amplifierwere described in the previous section. We have seen that the advantages of the microwave Doherty amplifier are the simple circuit configuration and improved efficiency and linearity. In this section, we explain some typical issues with Doherty amplifiers and present proposed methods to address them.The Doherty amplifier for the base station system usually has two amplifiers with identical size devices, matching circuits, and input drives. Because the peaking amplifier is biased lower than the carrier amplifier, the current level of the peaking amplifier at the maximum input drive cannot reach the maximum allowable current level. Thus, the load impedances of both amplifiers can not be fully modulated to the optimized impedance, Zopt, and they are larger than the optimum values. As a result, the conventional Doherty amplifier is heavily saturated, and both linearity and power are degraded. It is difficult to improve the linearity of the Doherty amplifier across a wide bandwidth due to the memory effect. We propose the following three design methods for wide bandwidth, high linearity, and high power applications: 1) Uneven power drive, applying more power to the peaking amplifier, can open the peaking amplifier fully and modulate the load impedances optimally. Therefore, the amplifiers with uneven power drive operate more linear and produce more power than those with an identical input power drive. 2) Because of the improper load modulation, power matching circuits of bothamplifiers should be appropriately designed to have low load impedances for better linearity. Due to the low bias point of the peaking amplifier, the power matching circuit of the peaking amplifier should be designed to have lower load impedance than that of the carrier amplifier. Moreover, the matching circuits of both amplifiers should be individually optimized to enhance the IM cancellation over power ranges across the wide bandwidth.3) The bias circuit should be designed to minimize the memory effects. The linearizing techniques focused on harmonic cancellation such as Doherty amplifier and PD are restricted to a low cancellation limit because the memory effect brings about the different lower and upper spurious emissions. The bias circuit should not have any frequency dispersion of envelope impedance to minimize the memory effect. To reduce the memory effect, the bias circuit is optimized using a quarter-wave bias line and decoupling capacitors for each frequency. The tantalum capacitors are inserted within a quarterwave bias line for the short at the envelope frequencies. Additionally, the biases of both amplifiers are properly adjusted to maintain optimized linearity and efficiency.Bias Circuit Test to Reduce the Memory EffectsThe effects on the memory effect for different bandwidthsare ACLR or intermodulation distortion (IMD) asymmetry and bandwidth dependent adjacent channel leakage ratio (ACLR) or IMDcharacteristics. To reduce these effects or the memory effects, the load impedances of the bias circuit should be reduced to short the envelope frequency voltage component or maintained at the same value.We have tested several bias circuits to reduce the memory effect as shown in Figure 6. Figures 7 and 8 represent measurement results of load impedances corresponding to the bias circuit. Unfortunately, we cannot measure the envelope frequency load impedance (dc–20 MHz), but we have tested the load impedances at 100 MHz–5 GHz. We can analogize the envelope frequency load impedance of the bias circuit from these test results.The general bias circuit scheme of RF power amplifier is shown in Figure 6(b). From Figures 7 and 8, we have analogized that the envelope load impedances of the RF decoupling capacitor (10 pF) and envelope frequency decoupling capacitor (22 uF and 10 uF) were very small. Even though the envelope load impedances of this case are very small, the power amplifier has the serious memory effect.A cause of this result is that it is very difficult to short the envelope frequency voltage component because the load impedance of the high-power amplifier is very small. To minimize the memory effect, the load impedance of the bias circuit should be further reduced. Thus, we have proposed the bias circuit optimization method of the RF decoupling capacitor (10 pF) and envelope frequency decoupling capacitor [22 uF, 10 uF, and the tantalumcapacitor (1 uF) located within a quarter-wave bias circuit], and Figures 7(c) and 8(c) show more small envelope load impedances and lower load impedance variation than the general bias scheme at the low frequency. However, the impedance at RF is reduced by tantalum capacitor located within a quarter-wave bias line as shown in Figure 7(c). Thus, we need to optimize the bias circuit along with the matching circuit considering these effects. As a result, the proposed bias circuit optimization method can reduce the memory effect more efficiently than the conventional bias circuit method, and ACLR asymmetry is reduced.Implementation of the Doherty Amplifier and Measurement ResultsIn the previous section, we explained the basic Doherty operation and advanced design methods with uneven power drive, individually optimized matching, and bias circuit optimization. A2.14-GHz Doherty amplifier for the base station power amplifier is implemented using Freescale’s MRF5P21180 LDMOSFET. Figure 9 shows a photograph of the implemented Doherty amplifier applying the advanced methods. The uneven power drive is implemented using an Anaren’s 1A1305-5 (5 dB directional coupler) which delivers 4 dB more input power to the peaking amplifier than the carrier amplifier. The individual matching of the Doherty amplifier is further optimized to achieve high efficiency and linearity at 25 W (44 dBm) average output power. In the experiments, the suitableoffset line is 80.4◦, and the transformed output impedance of the peaking amplifier in the off state is 502 .Quiescent biases for the carrier amplifier and peaking amplifier are set to Vc = 3.938 V (1.1 A) and Vp = 1.713 V at Vdd = 27 V, respectively. We optimize the bias circuit to minimize the memory effect and improve the linearity and efficiency. For performance comparison, we also fabricated a class AB amplifier and Doherty amplifier with even power drive. The class AB amplifier represents a conventional base station power amplifier of the push-pull type. For specific comparison corresponding to uneven power drive, the Doherty amplifier with even drive is optimized using the individual matching and bias circuit to achieve linearity and efficiency as high as possible.Figure 10 shows the measured adjacent channel leakage ratio (ACLR) of the Doherty amplifier with uneven drive and class AB amplifier at offset 5 MHz for a 2.14-GHz forward link wideband code-division multiple-access (WCDMA) 4FA signal. The ACLR is improved by about 7 dB compared to the class AB amplifier at an output power of 44 dBm.Figure 11 shows the measured ACLR of the Doherty amplifiers for both even and uneven drives. In comparison with the even case, the Doherty amplifier with uneven power drive delivers significantly improved ACLR performance, by 3 dB at the average output power of 44 dBm.Figure 12 shows the measured ACLR performance of the uneven case as a function of the bias circuit optimization. The drain bias circuit incorporates a quarterwave line and several decoupling capacitors which consist of 10 pF for the RF and 22 uF, 10 uF, 1 uF, 1 nF, 150 nF for the envelope frequency. The tantalum capacitors (22 uF, 1 uF) located within a quarter-wave bias line are especially important to minimize the memory effect, even though the impedance at RF is reduced by these capacitors. Thus, we have optimized the bias circuit along with the matching circuit considering these effects. As a result, the bias circuit becomes an active matching circuit, and the difference in ACLR with the bias circuit optimization between lower and upper ACLR is reduced below 2 dB over all average output powers. Figure 13 shows the spectrum of the Doherty amplifier with uneven power drive at an average output power of 44 dBm according to the bias circuit optimization.Figure 14 shows the measured IMD3 of the Doherty amplifier with both even and uneven power drives for a two-tone signal. We measure a peak envelope power (PEP) using a two-tone signal with 1-MHz tone spacing. The PEP of the amplifier with uneven drive is improved by 15 W, from 165 to 180 W, compared to the even case. This result implies that the Doherty amplifier with uneven power drive generates full power from both amplifiers.Figure 15 shows drain efficiencies of the Doherty amplifierwith both even and uneven power drive and the class AB power amplifier for WCDMA 4 FA signal. The drain efficiency of the Doherty amplifier is significantly improved over the class AB amplifier.These results show clearly that the Doherty amplifier is far superior to the class AB amplifier. The Doherty amplifier with uneven power drive, based on the individually optimized matching circuit and the bias optimization, provides highly efficient and linear operation compared to the normal Doherty amplifier. We can also see that the proposed design method is very helpful in achieving the Doherty amplifier with high performance over a wide bandwidth.ConclusionsIn this article, we explained the basic Doherty operation principle, including both efficiency and linearity improvements, and the circuit configuration of the normal Doherty amplifier. We proposed advanced design methods for highly efficient and linear Doherty amplifier operation across a wide bandwidth. The Doherty amplifier is implemented using Freescale LDMOS MRF5P21180. The amplifier utilizes uneven power drive, individually optimized matching, and bias circuit optimization.For a 2.14-GHz WCDMA 4 FA signal, the Doherty amplifier has ACLR of −41 dBc and a drain efficiency of 33% at an average output power of 44 dBm. These experimental results clearly demonstratethe superior performance of the Doherty amplifier compared to class AB amplifiers and conventional Doherty amplifiers. The proposed design methods are well suited for the design of the Doherty amplifier for wide-bandwidth and high-power operation.。
Giga-tronics 8650A系列通用电源表说明书
19818650AS ERIESU NIVERSALP OWERM ETERSThe Giga-tronics 8650A Series combines the speed,range and capabilities needed to test today’s sophisticated communications systems.sors,or from forgetting toThe Secret is the SensorsPULSE POWER MEASUREMENTS Attach a Giga-tronics 80350A Series Peak Power Sensor to an 8650A meter and directly measure the instantaneous peak power level of a pulse modulated e the ‘sample delay’ function to set the desired measurement point on the wave-form.And an external scope can be used to view the profile and see the exact measurement point on the pulse.Giga-tronics power meter architecture provides for a broad choice of functional sensors.Just by changing a sensor,you can measure CW power,pulse power,and the peak and aver-age power of TDMA,GSM and CDMA signals faster,more accurately,and over a wider range.THEFASTESTCW MEASUREMENTSGiga-tronics 80300A Series CW Power Sensors let you measure CW power from 10 MHz to 40 GHz at more than 1,750readings per second over GPIB.Measure up to 90 dB with a single sensor,and select from a variety of high power sensors,up to 50 W .MODULA TEDPOWER MEASUREMENTSThe Giga-tronics 80400A Series Modulated Power Sensors let you measure the average power of ampli-tude modulated,burst modulated and other complex modulated signals — suchas TDMA signals — at bandwidths up to 40 kHz.The Giga-tronics 80600A Series Modulated Power Sensors provide bandwidth up to 1.5 MHz to measure the peak and average power of CDMA signals.And the Giga-tronics 80701A Modulated Power Sensor operating with the 8650A power meter,provides system bandwidth up to 10 MHz to measure the peak and average power of wide band,third-genera-tion CDMA signals over an 80 dB range.Displays of IntelligenceSEE FOR YOURSELFThe 8650A incorporates a 3.72” wide by 2.15” high Liquid Crystal Display (LCD)with 240 x 120 dot resolu-tion,0.38 mm dot pitch,and Cold Cathode Fluorescent Lamp (CCFL) back light for maximum detail and opti-mum viewing.The large display lets you see more information.And the display works in tandem with the meter controls to let you view menu selections and see your input data as you enter it.Y ou can view calibration information,select a standard mode,setup and recall pre-configured,custom modes,and set measurement points and durations.Each sensor uses an EEPROM to store values of cal factor.Enteringthe measurement frequency automatically calls up the correct cal factor.If the measurement frequency is between cal factor points,the meter automatically enters an interpolated value.An extensive list of help panels provide assistance in setting up special features and guidance in making the measurement.A volts per frequency input isavailable to set the cal factor when connected to an RF source.As the source frequency is modified the V/F output will automatically set the power meter to the correct cal factor,thereby eliminating the need for manual input.Peak (Pulse) power sensors can be set to the desired measurement point of a pulse signal.The trigger point can be set using an internalpower level or a TTL signal.Recall setup can be used to pre-configure measurement modes for later use.Full descriptive details help to clearly identify the settings before recall.The graphic display provides visual feedback as you set the measurement start time and duration of the time gate to measure the average power during a specific time period.View the mean power and standard deviation of the modulated signal over a time period of interest.Standard deviation offers an alter-native descriptive analysis of the power variation when compared to the traditional crest factor.ST A TISTICAL ANAL YSISExcessive cost can prove as detrimental to the success of communications equipment as inadequate performance.The 8650A provides a range of statistical power measurement analysis fea-tures that help you optimize your designs to prevent inad-equate performance due to under design or excessive cost due to over design.These features include crest factor,standard devi-ation,strip chart,CDF/CCDF ,and histogram,and they let you view and thoroughly analyze the power signal over a selected period of time.Combined,they make the 8650A the most advanced power meter available for communications systemsdesign.The histogram function allows youto view a power range distribution over a period of time.The x axis displays the minimum to maximum power levels measured during the interval time period,and the y axis displays the percent of time each power level is measured.A zoom feature lets you view smaller seg-ments of the power range to bet-ter analyze the percentage of time a specific power level has occurred.The strip chart function allows you to view the vary-ing power levels of a signal over a period of time.The x axis displays time from the start of the meas-urement to a selectable period of 1 to 200 minutes,and the y axis displays the minimum to maximum power levels measured during the selected period.Moving a cursor along the x axis displays time and the corresponding power level.The Cumulative Distribution Function (CDF) shows the percentage of time a signal is below a selected power level.Thex axis displays the amount of power at the selected level,meas-ured in dBm,and the y axis dis-plays the percentage of time the power is at or below the power specified by the x axis.The Complementary Cumulative Distribution Function (CCDF) reori-ents the CDF curve in accordance with the equation CCDF = 1-CDF for more accustomed viewing of a descending slope.Moving a cursor along the slope of the curve dis-plays the power level in dBm and the corresponding percentage of time the signal is above that level.The K connector is electrically and mechanically compatible with the APC-3.5 and SMA connec-tors.Note:Use a Type N(m) to SMA(f) adapter (part no.29835) for calibration of power sensors with Type K(m) connectors.Power coefficient equals <0.01 dB/Watt.Power coefficient equals <0.015 dB/Watt.For frequencies above 8 GHz,add power linearity to system linearity.Power coefficient equals <0.01 dB/Watt (Average).Power coefficient equals <0.015 dB/Watt (Average).Peak operating range above CW maximum range is limited to <10% duty cycle.Square root of the sum of the individual uncertainties squared (RSS).Cal Factor numbers allow for 3% repeatability when reconnecting an attenuator to a sensor and 3% for attenuator measurement uncertainty and mismatch of sensor/pad combination.Depending on sensor used.MAP (Modulated Average Power),PAP (Pulse Average Power),BAP (Burst Average Power).Specified performance applies with maximum averaging and 24 hour warm-up at constant temperature.Operates in Normal Mode only.Display contrast reduces above 50°C.Does not apply to 80701A Sensor below 500 MHz.Specifications subject to change without notice.Specifications describe the instrument’s warranted performance,and apply when using the 80300A,80400A,80600A,and 80700A Series Sensors.METERFrequency Range:10 MHz to 40 GHz 10Power Range:-70 dBm to +47 dBm (100 pW to 50 Watt) 10Single Sensor Dynamic Range:10CW Power Sensors:90 dB Peak (Pulse) Power Sensors:40 dB,Peak50 dB,CWModulation Power Sensors:87 dB,CW80 dB,MAP/PAP 1160 dB,BAP 11Display Resolution:User selectable from 1 dB to 0.001 dB in Log mode,and from 1 to 4digits of display resolution in Linear mode.Meter FunctionsMeasurement Modes (Sensors):CW (80300A,80350A,80400A,80600A,and 80700A Series)Peak (80350A Series)MAP/PAP/BAP 11(80400A,80600A,and 80700A Series)Averaging:User selectable,auto-averaging or manual from 1-512 readings.Timed averaging from 20 ms to 20 seconds.dB Rel and Offset:Power display can be offset by -99.999 to +99.999 dB to account for external loss/gain.Configuration Storage Registers:Allows up to 20 front panel setups.Power Measurements and Display Configurations:Any two of the following channel configurations,simultaneously:A,B,A/B,B/A,A-B,B-A,DLYA,DLYB Number of Display Lines:4Sampling:CW and Modulation Mode: 2.5 to 5 MHz asynchronous Analog Bandwidth:CW Mode:≥3 kHzModulation Mode:>10 MHz Time Gating:Trigger Delay:0 to 327 ms Gate Time:10 µs to 327 ms Holdoff Time:0 to 327 ms ACCURACY50 MHz Calibrator:(Standard)Calibrator:+20 dBm to -30 dBmpower sweep calibration signal to dynamically linearize the power sensors.Connector:Type N,50 ΩFrequency:50 MHz,nominal0.0 dBm Accuracy:±1.2% worst case for one year,over temperature range of 5º to 35ºC.VSWR:<1.05 (Return Loss >33 dB) @0 dBm.1 GHz Calibrator:(Option 12)Required for 80700A Series Sensors.Calibrator:+20 dBm to -30 dBmpower sweep calibration signal to dynamically linearize power sensors.Connector:Type N,50 ΩFrequency:(Switchable):1 GHz,nominal;50 MHz,nominal0.0 dBm Accuracy:±1.2% worst case for one year,over temperature range of 5º to 35ºC.VSWR:<1.07 (Return Loss >30 dB) @0 dBm.800 MHz - 1 GHz Synthesizer Specifications:(Option 12)Power Range:+15 dBm to -30 dBm,settable in 1 dB steps.Frequency:800 MHz to 1 GHz,settable in 1 MHz steps.Power Stability:<0.1 dB/Hour Frequency Accuracy:±0.05%Instrumentation Linearity:±0.02 dB over any 20 dB range from -70 to +16 dBm.15±0.02 dB + (±0.05 dB/dB) from +16 to +20 dBm.±0.04 dB from -70 to +16 dBm.Graph shows linearity plus worst case zero set,and noise versus input powerTemperature Coefficient ofLinearity:<0.3%/ºC temperature change following Power Sweep calibration.24 hour warm-up required.Zeroing Accuracy:(CW)Zero Set:12<±50 pW,<±100 pW with80400A and 80600A Series Modulation Power Sensors.<±200 pW with 80700A Series Sensors.Zero Drift:12<±100 pW during 1 hour,<±200 pW with 80400A and 80600A Series Sensors,<±400 pW with 80700A Series Sensors.Noise:<±50 pW,<±100 pW with 80400A and 80600A Series Modulation Power Sensors.<±200 pW with 80700A Series Sensors.Measurable over any 1 minute interval after zeroing,3 standard deviations.REMOTE INPUTS/OUTPUTSV Prop F Input (BNC):Sets calibration factors using source VpropF output.13Analog Output (2) (BNC):Provides an output voltage of 0 to 10V for Channels 1 and 2 ineither Lin or Log units.13Does not operate in Swift or Buffered modes .Trigger Input (BNC):TTL trigger input signal for Swift and Fast Buffered modes.GPIB Interface:IEEE-488 and IEC-625 remote programmingRS232 Interface:Programmable serial interface,DB-9 connector GENERAL SPECIFICATIONS Temperature Range:Operating:0º to 55ºC (+32º to +131ºF)14Storage:-40ºC to 70ºC (-40º to +158ºF)Power Requirements:100/120/220/240V ±10%,48 to 440 Hz,25VA typical Physical Characteristics:Dimensions:215 mm (8.4 in) wide,89 mm (3.5 in) high,368 mm (14.5 in) deep Weight:4.55 kg (10lbs)ORDERING INFORMATION POWER METERS 8651A Single Input Universal Power Meter(includes 1 sensor cable)8652A Dual Input Universal Power Meter(includes 2 sensor cables)ACCESSORIESOne manual,one power cord.POWER METER OPTIONS 01Rack mount kit038651A Rear Panel Sensor and Calibrator Connections 048652A Rear Panel Sensor and Calibrator Connections 05Soft Carry Case07Side Mounted Carrying Handle08Transit Case,(Includes Soft Carry Case)09Dual Rack Mount Kit (with assembly instructions)10Dual Rack Mount Kit (factory assembled)12 1 GHz,50 MHz Switchable Calibrator 138651A Rear Panel Input Connector 148652A Rear Panel Input Connectors80301A 80310A 80320A 80321A 80322A 80325A 80330A80401A, 80601A (CW)80701A (CW)-70-64-60-50-40-40-30-67-64-60-54-50-40-30-30-20-57-54-50-44-40-30-20-20-10-47-44-40-34-30-20-10-100-37-34-30-24-20-100010-27-25-20-14-100101020-17-16-10-40102020-7-7061020303033101620304040131320253040445020203210-1-2-3S E N S O R ST Y P I C A L E R R O R (d B )Input, (dBm)Giga-tronics Incorporated 4650 Norris Canyon Road San Ramon,California 94583T elephone:800 726 4442 or925 328 4650T elefax:925 328 4700Web Site:© 1999 Giga-tronics IncorporatedGT-167-B。
7-power supply(功率补偿)
Passage 7
Diode and power supply 单击此处编辑母版标题样式
It may be thought of as the normal or standard type of diode in use today. These diodes can come as small signal types for use in radio frequency, or other low current applications which may be termed as signal diodes.
"Charge carriers" are any particles possessing an electrical charge. Different types of substances have different charge carriers: Metals: "free" (conduction-band) electrons Semiconductors: electrons and holes Liquids: ions
Passage 7
Diode and power supply 单击此处编辑母版标题样式
6 The characteristic curve for a normal PN junction rectifying diode looks something like this:
1. Characteristic curve 特性曲线
Passage 7
Diode and power supply 单击此处编辑母版标题样式
• 阅读教材380
3GPP LTE 中ofdma和sc-ofdma的比较
3GPP LTE OFDMA和SC-FDMA多址接入方案的研究摘要LTE在下行采用正交频分复用多址接入(OFDMA)技术，因为OFDMA具有较高的峰均功率比（PAPR）。
这对发射机功放的线性度要求较高，使得发射机成本明显增加;其次OFDMA要求子载波严格正交，因此它对频率偏移会比较敏感。
单载波频分多址接入技术(SC-FDMA)是OFDMA技术的改进,相较于OFDMA，两者的系统结构和性能比较相似，但它具有低PAPR 特性与对频率偏移不敏感的优势，并同样能在接收端应用频域均衡技术来有效对抗多径衰落的影响。
因此3GPP决定在LTE上行采用SC-FDMA技术作为多址接入方式。
本文将给出一个关于正交频分多址(OFDMA)和单载波频分多址(SC-FDMA)的概述,并对两者进行比较，利用Matlab对二者的PAPR进行了仿真，验证了SC-FDMA比OFDMA有较低的PAPR。
此外，还研究了不同均衡方式和不同信道模型下的SC-FDMA的误码性能并得出相关结论。
关键词：OFDMA；SC-FDMA；峰均功率比Study of Multiple Access Schemes in 3GPP LTEOFDMA vs. SC-FDMAABSTRACTWith the continuously developing of wireless communication technique and the users' high demands to communication, 3GPP proposed LTE (Long Term Evolution) standard as the transition from3G to 4G while LTE downlink adopts orthogonal-frequency-division-multiplexing access (OFDMA) technique, OFDMA is not suitable for LTE uplink because of its disadvantages. The first main disadvantage is that OFDM signal's peak-to-average power ratio (PAPR) is very high, which decreases the power efficiency of mobile terminal and proposes higher demands on the linearity of transmitter power amplifier, which will increase the cost of transmitter. Secondly, OFDMA requires strict orthogonality among sub-carriers,Which makes it sensitive to frequency offset. Single-carrier frequency division multiple access (SC-FDMA) technique is the improvability of OFDMA techniques. Possessing the similar structure and performance as OFDMA, SC-FDMA shows the advantage of lower PAPR feature and being not sensitive to frequency offset. Besides,SC-FDMA can adopt frequency equalization technique at the receiver to overcome the influence of multi-path fading. So, 3GPP decided to adopt SC-FDMA, to be the multiple access technique in the LTE uplink.In this paper, we give an overview of both OFDMA and SC-FDMA, then draw a comparison and analysis with ing MATLAB on a combination of PAPR, verify that SC-FDMA had lower PAPR than OFDMA.we also studied different ways of balancing and SC-FDMA BER performance under different channel models and draw relevant conclusions.Key words：OFDMA；SC-FDMA；PAPR目录1 前言 (1)1.1 3GPP LTE的发展概况 (1)1.2本文的研究内容和篇章结构 (1)2 OFDM技术简介及原理 (2)2.1 OFDM技术简介 (2)2.2 OFDM系统的算法和工作原理 (2)3. OFDMA技术 (3)3.1 OFDMA技术简介 (3)3.2 OFDMA的优缺点 (3)4 SC-FDMA技术 (4)4.1 SC-FDMA的基本原理 (4)4.2 SC-FDMA子载波映射方式 (5)4.3 SC-FDMA的实现形式 (6)4.3.1.时域信号产生 (6)4.3.2 频域信号的产生 (6)4.3.3 两种实现形式的比较 (7)5 SC-FDMA与OFDMA的比较 (7)5.1 峰值平均功率比 (8)5.2仿真结果 (9)5.2.1不同调制方式下OFDMA和IFDMA系统PAPR性能仿真 (9)5.2.2不同子载波映射方式下的SC-FDMA系统PAPR性能仿真 (10)6 结论 (11)参考文献 (11)1 前言1.1 3GPP LTE的发展概况第一代移动通信系统起始于19世纪70年代，它采用频分多址(FDMA)技术的模拟移动通信系统，重要缺点是频带利用率低、保密性差、终端体积大且只能供给语音业务。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
Application Note AN-50 1 Apr. ‘93MEASURING THE PEAK-TO-AVERAGE POWER OFDIGITALLY MODULATED SIGNALSCharles J. Meyer, Senior Applications Engineer, Boonton ElectronicsAbstract - Digital vector modulation has become the preferred method of modulation used in modern digital transmission systems.This type of modulation, however, exhibits inherently high peak-to-average power ratios and requires a large linear dynamic range for proper operation. The peak power level changes continuously and randomly and occupies a large bandwidth. Conventional methods of measuring peak power prove to be unusable. This application note analyzes the sources of the peak power in digitally vector modulated systems and addresses the capabilities that are needed for proper measurement. The Boonton 4400 is presented as an advanced PeakPower Analyzer well suited for measurements of this type.Digital Vector ModulationDigital vector modulation is being utilized in a wide variety of tech-nologies such as digital cellular radio, high definition television (HDTV),satellite and microwave links, military communication, and numerous spread spectrum applications. Digital vector modulation is a com-plex modulation scheme whereby a signal’s phase and/or amplitude are altered to represent digital bit patterns called symbols. Specific phase/amplitude combinations are called symbol states and valid symbol states are defined on a vector map called an I-Q (in-phase -quadrature) diagram (Fig. 1).Schemes that modulate only a signal’s phase are often referred to as Phase-Shift Keying (PSK) modulations, whereas when amplitude and phase are both used to encode data, it is usually referred to as Quadra-ture Amplitude Modulation, or QAM. Variations of these basic schemes continue to emerge. A variation of PSK, called pi/4 differential quadra-ture phase-shift keying (pi/4-DQPSK), is used by the North American Digital Cellular (NADC) and Japanese Digital Cellular (JDC) formats,while another PSK variant, minimum shift keying (MSK), is used by the GSM European digital cellular format.Measuring the Peak Power of Complex SignalsSpecific factors contributing to peak power in digitally vector modu-lated systems will vary by scheme and implementation, but can be identified as arising from four primary sources. The sources are:multiple symbol power levels (caused by the multi-level voltage states in QAM type schemes), compound amplitude ringing (caused by the filtering of the baseband I&Q signals), multiple carrier power addition (caused by the vectorial summation of the voltages of multiple carri-ers in multi-channel schemes), and the peak cresting factor of a sinu-soidal wave (√22 or 3 dB) (Table 1).Accurate analysis of peak power must take these factors into ac-count. The contributions of the first three factors will combine to cre-ate the power envelope of the signal. The average (heating) power of the signal can be derived through RMS integration of the power envelope over time. Since envelope power is actually the track of average power as it dynamically changes in time, and a sinusoid’s peak power is 3 dB greater than its average power, peak instanta-neous power will exist 3 dB greater than the envelope power (Fig. 2).This “cresting factor”, is the forth factor, and it’s contribution should not be added when only the peak envelope power is to be consid-ered.The peak power envelope may become further altered (or distorted)by power amplifier non-linearities, spectrum-shaping filters, and RF transmission lines. Contributions from these additional sources can-not be easily calculated. The measurement of peak-to-average power is a ratio of the maximum peak envelope power to the average power in a system.Power Analysis of Digital Vector ModulationDigitally vector modulated schemes that modulate a signal’s ampli-tude (such as QAM), have multiple symbol power levels. Vectorial analysis of a signal’s I-Q diagram will reveal these levels (Fig. 3).Since each symbol power level represents multiple symbol states (and all of the data associated with those states), any system non-linearities that could alter one of the symbol power levels (such as AM/AM or AM/PM distortions) would also affect the system symbol error rate (SER). Impairments of this type would easily generate SERs high enough to quickly disable an entire system.I IQ Q Q I IQI 16-QAM32-QAMQ 64-QAM BPSKQPSK 8-PSK QI 1b it p e r s ym b o l s t a te 2 b its p e r s ym b o l s t a te 3 b its p e r s ym b o l s t a te5 b its p e r s ym b o l s t a te 4 b its p e r s ym b o l s t a te6 b its p e r s ym b o l s t a te Figure 1 - Typical I-Q DiagramsTable 1 - Factors that contribute to peak-power in a systemFigure 2 - Envelope Power vs. Peak Instantaneous PowerMultiple symbol power levels (QAM type schemes) Compound ringing caused by baseband filtering Power vector addition caused by multiple carriers Sinusoidal cresting factorVoltage vs. TimePower vs. TimePeak InstantaneousPEnvelope Power(Averaged Instantaneous Power)Assuming that all symbol states are occupied equally over time,then it is possible to calculate the peak-to-average symbol power and dynamic range requirements of a complex signal (Tables 2and 3)1. Note that this analysis considers only the basic signal without baseband filtering (Fig. 4). PSK modulations have only one symbol power level, but they are still vulnerable to amplifier nonlinearity distortions (especially AM/PM).Baseband filtering will introduce an additional peak power contri-bution in the form of compound amplitude ringing. Digitally modu-lated signals require baseband filtering because of their theoreti-cally infinite bandwidth (as defined by the function (sin x)/x. To limit a signal’s bandwidth, the I&Q modulator signals must be fil-tered so that the digitally driven modulator does not have to “in-stantly” transition to the next symbol state. A digital transition causes an impulse response that has an infinite Fourier series. Convolu-tion of this series with a bandwidth limiting function (filter) results in truncation of the series. Ringing (or Gibbs phenomena) occurs whenever a Fourier series is truncated 2 (Fig. 5).The amplitude of the ringing will vary from symbol to symbol be-cause certain phase/amplitude changes will be more drastic than others. This is compounded by residual ring voltages that are still decaying from previous symbol changes. Although well designedFigure 4 - Nine symbol power levels of a 64-QAM (unfiltered)Figure 5 - Gibbs phenomena on PI/4-DQPSK NADC signalbaseband filters will keep this effect to a minimum, power ringing will unavoidably occur in proportion to the value of the compounded ring voltage squared.The effect of symbols randomly transitioning across multiple power lev-els combined with the compound ringing from the baseband filters will produce a complex power envelope that is continuously changing and may even seem to resemble white noise (Fig. 6). The highest (peak)power levels of this signal must be preserved within the linear region of an amplifier. Failure to do this has serious consequences since com-pression of the peak power will cause significant intermodulation dis-tortion products (IMD), reduced signal robustness, and if severe enough,a significant data loss.Because of these reasons, QAM signals are often operated with aver-age power levels 9 to 15 dB below a power amplifier’s saturation level.PSK amplifiers usually require at least 7 to 10 dB of output “backoff” as well. Accurate measurement of the peak power is necessary since only 3 dB of error equates to 50% linear error. This could be the differ-ence between choosing either a 5 kW or a 10 kW transmitter for the same system.Monitoring the peak-to-average power ratio of a transmitter will provide valuable information about how a complete system is behaving. Any change in the ratio would be indicative of a problem somewhere, such as: degradation of the transmitter’s peak power handling capability, signal compression, up-converter problems, modulator system problems, etc.Multiple Carrier TransmissionsTransmitters that support multi-channel operations (multiple simulta-neous carriers) are further challenged due to the peak power effect that results from the vectorial addition of the voltage waveforms of each individual carrier. Each time that the number of carriers (with equal power) in a system are doubled, the peak-to-average power ratio will increase by 3 dB (Table 4) (Fig. 7).16-QAMQ3 2 2 32 1 1 22 1 1 23 2 2 332-QAMQ 5 4 4 55 3 2 2 3 54 2 1 1 2 44 2 1 1 2 45 3 2 2 3 55 4 4 564-QAMQ9 8 7 6 6 7 8 8 6 5 4 4 5 6 7 5 3 2 2 3 5 6 4 2 1 1 2 4 6 4 2 1 1 2 4 7 5 3 2 2 3 5 8 6 5 4 4 5 6 9 8 7 6 6 7 8 I IFigure 3 - Relative voltage magnitude levelsQI16-QAM1111222222223333Peak/Average Power Ratio = 9/5 = 1.80 = 2.55 dBDynamic Range = 9/1 = 9.54 dBNumber of Occurences (b)Weighted Symbol Power(a)*(b)1231594844403680165 Total weighted symbol power :divided by total number of symbol states :Average symbol power magnitude :Peak symbol power magnitude :Symbol Power Level Number PowerVector Magnitude (a)Table 2 - Calculation of Symbol Power for 16-QAMType of Vector Modulation Number of Symbol Power Levels Peak-to-Avg Symbol Power Ratio dB DynamicRange Ratio dB Percent of data in highest Power level Percent above average power level16-QAM 3 1.8:1 2.55 9:19.5425.0 %25 %32-QAM 5 1.7:1 2.30 17:112.3125.0 %50 %64-QAM 9 2.3:1 3.68 49:116.90 6.3 %50 %256-QAM 32 2.7:1 4.23 225:123.52 4.6 %*45 %256-SSQAM301.9:12.85 157:121.9625.0 %*52 %* Highest 1 dB of powerIn an example situation of 32-10W carriers, each being QPSK modu-lated, and having peak-to-average power ratios of 3dB (caused by baseband filter ringing), the combined average power would be 320Watts (55 dBm), but because the total peak-to-average power ratio would be 21 dB (Table 5), the peak power could reach to almost 40,000 Watts (76 dBm). If the power amplifier were rated for linear operation to 5 kW, since the peak-to-average power demand could not be supported, all peak power occurrences greater than 5 kW would drive the amplifier into compression and toward saturation.If we constructed a histogram of the power levels, totaling all random occurrences of peak power by level, we would see a statistical distri-bution with a diminishing number of occurrences as we approached the highest levels. If these were FM carriers, the number of peak power occurrences at and above the power amplifier’s compression level would represent the amount of crosstalk and IMD being toler-ated. But with digital modulation, this could also represent instanta-neous occurrences of symbol destruction on every carrier simulta-neously.Assuming that the peak power occurrences are of a very small dura-tion compared to the symbol rate and that the amplifier can quickly recover from these occurrences, the symbol information may be re-coverable and the transient IMD may be able to be tolerated. Yet if the peak power was known continuously (by monitoring), and the amplifier gain could be varied, then the maximum transmitter output could be maintained while holding a safe backoff from compression.Power Domain AnalysisThe successful implementation of a digitally modulated system re-quires that the peak and average power levels be accurately mea-sured. These measurements must be derived from a power domain analysis, or an analysis of the peak power envelope as it changes in and through time. The value for average power can be determined through continuous RMS integration of the power envelope.Figure 6 - 16QAM, 5MSymbol, .2 sq. root raised cosine filterFigure 7 - Peak power profile of a four carrier transmissionPower domain analysis requires measuring scalar power as it occurs in the time domain. This can be viewed in contrast to traditional sca-lar analyzers that measure scalar power in the frequency domain.This type of analysis was first defined by commercial and military requirements to analyze pulsed power transmitters. They needed to accurately measure specific pulsed power envelope parameters in the time domain. The peak power meter was first developed to meet those needs.Other traditional instruments useful for power measurement, are not suitable for power-domain analysis. Spectrum analyzers, for example,have bandwidth and mixer limitations and lack the accurate power measurement traceability of a power meter. Conventional averaging power meters are also not suitable for this type of analysis since they are designed to continuously average a dynamic power envelope.They can, however, be used to provide true RMS average power information.Thermocouple sensors thermally derive the measurement of true average power, while averaging diode sensors use resistive-capaci-tive loads with long R-C time constants to provide an average voltage response proportional to the average RF power input level. Averag-ing diode sensors also cannot be used to measure the true RMS power of complex waveforms unless the peaks of the complex wave-form exist completely within the square-law limits of a full-wave recti-fying diode circuit 3.Peak Power MetersPeak power meters are designed to provide accurately calibrated detection of envelope power across a wide dynamic range. Like av-erage power meters, they also minimize sensor errors by providing a high-precision RF load (low SWR) with compensation for frequency and temperature variations.However, power domain analysis of a digitally modulated signal re-Numbers of Carriers (n)(1W each)Average Power (Pavg)Watts dBm Peak Power (Ppk = n*Pavg)Watts dBm Peak-to-Average Power Contribution Ratio dB124816326412813023343683916423245644812851130436164264482565410246040966616.4 k 721:102:134:168:1916:11232:11564:118128:121Table 4 - Peak power contribution of multiple carriersPeak Power Contribution :32 ch.QPSK 1 ch.16-QAM 128 ch.32-QAM Pk/Avg Symbol power Baseband filter ringing Multiple carrier addition Sinusoidal cresting factor 0 dB 3.0dB 15.0dB 3.0dB 2.6dB 4.5dB 0dB (ignore) 2.3dB 5.2dB 21.0dB 3.0dB Total Peak-to-Average Power :21.0dB7.1dB31.0dBTable 5 - Example peak/avg power for different systemsquires a peak power meter with advanced features. The peak power sensor must be a fast, average-responding diode type, providing a accurate voltage output proportional to the RF power envelope of the applied signal. This is to accurately follow the details of the power envelope and to capture all transients of the envelope that occur to the frequency limit of the sensor’s video bandwidth.The sensor’s video bandwidth specification should be sufficient to capture all power transitions related to a symbol change. Any power transitions occurring above the limit of a sensor’s video bandwidth will be averaged by the diode’s video load. These sensors typically use diodes in a full-wave rectification method to insure accurate de-tection of both positive and negative voltage transitions. The sinusoi-dal peak cresting factor occurs at the signal’s RF rate (significantly higher than a sensor’s video bandwidth) and its contribution will be averaged into the power envelope of a signal (as it should be). When it needs to be considered, its 3 dB (√22) factor must be added to the measured value of peak (envelope) power.The sensor diode’s video output must be supported by a wide dy-namic range amplifier such as a logarithmic amplifier. This is neces-sary to accurately track a signal through large peak-to-average power levels and to preserve the details of large power transitions. The amplifier’s output must then be digitized at high speed with high reso-lution. High Speed sample and hold circuits and flash type A/D con-verters are often used to perform this type of digitization.The number of bits used to digitize the signal will determine the power measurement resolution. When the percent bit resolution is applied across the full dynamic range of the logarithmic amplifier, the quanti-zation level resolution is established (Table 6). This resolution must be fine enough to accurately discern the smallest power level of inter-est.Video averaging is often used to interpolate the area between the quantiza-tion levels. This has an effect as if the number of bits of resolution could be increased and it is usually referred to as “averaging the signal”. By averaging a PSK/QAM signal in this way, peak power information is lost. This is be-cause the power envelope is not repetitious with time, but continuously chang-ing from symbol to symbol. In fact, the highest levels of a QAM signal’s power envelope willoften be reached less than 1% of the time. So signalFigure 8 - The 4400 tracks power over a large dynamic range averaging must not be used.The acquisition system must use very high speed sampling, or else use a technique such as random repetitive sampling to provide true statistically random sampling. The system should also acquire power data with or without a repetitive trigger event. This is important in situations where a symbol trigger is not available or with complex multiple carrier transmissions.Finally, consideration also must be given to the processing system since acquisition speed (samples per second) does not take into ac-count how effectively the processing system can utilize these samples.When significant mathematical processing is required (such as con-tinuous integration of the peak power envelope), a weak processing system may be forced to ignore a significant percentage of the avail-able samples because it will not have the time to process them.Boonton 4400 Peak Power MeterThe Boonton 4400 is an advanced peak power meter designed to support extensive power domain analysis. It combines powerful sig-nal acquisition and digital signal processing with a versatile set of user interface features. It can accurately track and analyze dynamic power envelopes on either continuous or pulsed signals, whether re-petitive or not, from 30 MHz to 40 GHz (depending on sensor) with NIST traceable accuracy.Its 56318 peak power sensor can accurately track power envelope transitions up to 35 MHz (video bandwidth limit) across over 47 dB of dynamic range (Fig. 8). Envelope transitions that are faster than this,are averaged down to the video bandwidth limit (pulse rise/fall time measurements are possible to less than 10 ns). Diode response is tracked with a logarithmic amplifier which is random-repetitively sampled by a 12-bit flash acquisition system digitizing at 1Msample/sec (timebase 50us or faster, else .5 MSample/s).A dedicated 32 bit floating point digital signal processor (DSP) con-tinually process this data and executes all mathematical analyses with negligible sample decimation. The DSP system can perform true integral RMS averaging on any portion of the power envelope by simply referencing the area of concern between two time markers.This can be used to determine the average power within a pulse or across the entire display screen (the DSP converts all data to linear values for RMS integration). The area between these markers also can be analyzed to indicate the maximum and minimum power lev-els, long-term peak power level (peak-hold), long-term RMS average power level (LAVG), and peak-to-average power ratio (Fig. 9).Table 6 - Power measurement resolution comparisonDynamic Range Digitizing Bits Percent Bit Resolution Minimum PowerMeasurement Resolution 50 dB 50 dB 50 dB 50 dB 50 dB 8101214160.391%0.098%0.024%0.006%0.002%0.195 dB 0.049 dB 0.012 dB 0.003 dB 0.001 dBThe DSP performs all measurement analysis directly on the acquired data (not on the displayed data), and it only requires proper trigger and timebase information for it’s automatic operations. A dedicated video graphics processor is used to continually processes the power envelope data for display on the integral high resolution 256 color VGA compatible display. Both logarithmic and linear display modes are available for analysis. The screen display can be plotted or printed to a variety of supported devices. Amplitude reference lines are pro-vided to index absolute power levels on the VGA display. This fea-ture, combined with display persistence, allows the dynamic range of a signal (or multiple signals) to be easily measured (Fig. 10).On slower timebase settings (10 msec/div and slower), the DSP can process many more samples than can be displayed. In this situation,the DSP will over-sample to determine a pixel’s value. The user can select whether the DSP will average a set of samples (normal mode),or select the highest value of the set (peaking-mode), to represent a pixel’s value. Using peaking-mode, the DSP can peak-detect up to 5million continuously acquired samples in one sweep. Peak power data can also be continuously transferred to a host computer via the IEEE-488 GPIB port. This feature can be used to support extensive user analyses such as transmitter power histograms, cumulative dis-tribution analysis, and peak power monitoring (Fig. 11).Figure 10 - Minimum and Maximum Power on a NADC transmission Figure 11 - Power histogram distribution of a 32-QAM signalConclusionFor more information contact :Boonton Electronics Corporation25 Eastmans Road, PO Box 465, Parsippany, NJ 07054-0465Telephone : (973) 386-9696, Fax : (973) 386 9191 E-Mail : Boonton@References1‘Measuring Peak and Average Power of Digitally Modulated Advanced Television Systems’,C.W.Rhodes & P. Crosby, IEEE Transactions on Broadcast Technology, December 19922Digital Filters R.W. Hamming, Prentice-Hall, 19773‘Diode Sensors for the Measurement of True Power’, R.E. Lafferty, Microwave Journal, November 1987The Boonton 4400 Peak Power Meter provides versatile and accu-rate measurement solutions for large dynamic range peak power analysis of PSK/QAM signals and multiple carrier transmissions. This type of power domain analysis is vital to insure efficient and effective results throughout the design, implementation, and maintenance stages of modern digital transmission systems.Note: The histogram distribution program is now incorporated into the model 4500A Peak Power Analyzer as part of its statistical func-tions.。