POCSAG Information

The ADVISOR™ Message ReceiverPOCSAG Coding Rulesand suggestions for programming capcodesIndividual CodesGroup CodesMail Drop CodeTABLE OF CONTENTS POCSAG Coding RulesGroup Calls - GeneralPager group callTerminal group callInformation ServicesInvalid POCSAG codesCode Assignment StrategySource IdentificationFunction Codes for Information ServicesMessage Indication TypesMail DropPaging Terminal and Mail DropsMessage StorageGroup CallsGroup Call Capcode AssignmentCapcode Assignment IllustrationPOCSAG framesADVISOR™ Message Receiver - POCSAG Coding RulesThe Motorola ADVISOR™ is capable of supporting 1, 2, 3, or 4 POCSAG codes.Here are the rules when requiring two POCSAG codes:•Every pager must have a Code A.•Code A and Code B must be in the same frame.(formula provided below)Here are the rules when requiring three POCSAG codes:•Every pager must have a Code A.•Code A and Code B must be in the same frame.(formula provided below)•The frame of Code C cannot be equal to the frame of Code A and Code B.•The frame of Code A and Code B must be less than the frame of Code C.Here are the rules when requiring four POCSAG codes:•Every pager must have a Code A.•Code A and Code B must be in the same frame. (Formula provided below) •There must be a Code C to have a Code D.•Code C and Code D must be in the same frame•The frame of Code A and Code Be cannot be equal to the frame of Code C and Code D.•The frame of Code A and Code B must be less than the frame of Code C and Code D.Formula to find the frame number:•Divide each Capcode by 8.•Take the decimal remainder and multiply by 8.•The result is the value of the frame (or frame number).Code A=20176÷8=252208.75Example:orCode B=16576÷8=207201.75.75 x=6Frame=6More ExamplesFrame Remainder Math example0none0 x 8 = 01.125.125 x 8 = 12.25.25 x 8 = 23.375.375 x 8 = 34.5.5 x 8 = 45.625.625 x 8 = 56.75.75 x 8 = 67.875.875 x 8 = 7Group Calls - GeneralThere are two general methods of performing "group call." When several users are assigned to a common group so that they can all be paged in one transmission, this is called Pager group call. All the pagers in the group must have a common capcode. This type of group call is only possible with pagers that can have more than one capcode because of the requirement for both individual and group message reception. Since most modern pagers can be programmed with several different capcodes, this is now the most widely used type of group call.Another type of group call that is not used very much anymore, is the Terminal group call. In this type of group call, the individual capcodes within the group are unrelated to each other. This group call is initiated by sending one message to a subscriber record, or a "pilot number" in the paging terminal. The paging terminal contains all the members of that group stored in its memory. The terminal then sends the message to each subscriber in the group, one after another. This results in separate transmissions to each subscriber and is very expensive in terms of air time. Not all paging terminals can do a group call of this type, and some paging companies do not offer this type of group call to their customers although their terminal has the capability. There are two reasons for this: 1) This type of group call is wasteful of air time since the group call message must be sent separately to each member of the group, and 2) some older paging terminals slow down considerably while they search the whole data base to locate all the members of the group. This can also create a delay between the time the first pager in the group and the last pager, receive their copy of the message.Information ServicesSubscription to information services is a very promising application of radio paging. Information services may include news headlines, weather forecasts, sports scores, and financial information. It is important to understand how to properly assign group call or Mail Drop codes for this type of service for the following reasons:•The overall throughput of the paging system is dependent on the POCSAG batching efficiency of the system. The POCSAG code contains eight "frames"in each "batch" and all frames must contain some kind of information when a batch is transmitted to the pagers. Each pager capcode always gets sent in its assigned frame. So, if it is time to send out a POCSAG transmission, andthere are no pages waiting in queue for any of the eight frames, the pagingterminal must substitute an "idle codeword" (which is an unused capcode) to fill the space in the frame. The point is that if too many idle codewords aretransmitted this is a waste of valuable airtime, a decrease in the grade ofservice, and a reduction of the number of subscribers that can be supportedon the radio channel.•Properly assigned group call codes in the same frames as the individual codes, will not cause a decrease in the useful life of the pager's battery.Assignment of a second code, outside the frame of the individual code, willresult in an approximate 30% decrease in the pager's battery life.• A logical plan is required to allow for an orderly and well planned use of the two million POCSAG codes available per radio channel. The actual number is221 or 2,097,152 (* less some invalid codes as shown below). Or, if you count the total number of addresses, the number is 223 (over 8 million) per channel.There are about 250,000 available capcodes per frame.The POCSAG code makes it easy to order pagers evenly distributed across the eight frames of a batch. The eight frames are numbered zero through seven (0-1-2 3-4-5-6-7). If pagers for individual messaging use are programmed sequentially, they will be equally distributed, because each time the capcode is incremented by one, the next code is assigned to the next higher frame until frame seven is reached. After frame seven, the assignment jumps back to frame zero. This can be easily seen in the POCSAG frame tables that begin on page below.0000000to0000007* Invalid POCSAG codes:2007664to20076712045056to20450632097144and greaterCode Assignment StrategySince this is a paper about the ADVISOR pager, it will continue to be used as an example while different ideas are presented about pager code assignments. These same ideas should be applicable to other model pagers by taking into consideration their different specifications especially those relating to code and memory capacity.Source IdentificationIt was pointed-out previously that an ADVISOR pager can be programmed with up to four cap codes. Page one of this paper explained how these codes must be related to each other. Each POCSAG code has four "sub-codes" which are called, Function Codes, Addresses, or Source Identifiers. All three of these names are commonly used to describe the same thing. These codes were first used to show the source of atone-only page. By assigning different numbers to the paging terminal and then giving out these access numbers to certain people, it was possible know the source when receiving a page. For example you could give one number to your boss, another to your wife, and another to your secretary. When your (tone-only) pager beeps, a distinct sound would show which number at the paging terminal was called and therefore the source (or origin) of the call.It would work something like this: Your boss wants to get in contact with you, s/he would dial 364-3779. The public telephone network would switch the call to the carrier's paging terminal and relay the last four digits "3779" to the paging terminal. The paging terminal would use the incoming "3779" digits to look up your subscriber record. This record would show that your tone-only pager has capcode "1234567" with function code number one activated. The paging terminal would send your codeover the correct radio channel. IF you are within the radio coverage area, IF your pager is turned on, IF your battery is good, and IF there are no strong electrical noises in the vicinity, then your pager will beep. Key to identifying the source is that there are four different sounding beeps. The best way to show this is with another example:TelephoneNumber Capcode (Address)Source-codeAudible Alert364-37791234567 1 beeeepbeeeep 364-37801234567 2 bep-beeepbep-beeep 364-37811234567 3 beeep-bepbeeep-bep 364-37821234567 4 beep-beep-beep-beepSo, if you hear the sound associated with source-code (or address) number one, youknow it is your boss calling, the sound for source-code two means it is your wife, andthe sound for source code three could mean for you to call your secretary.That is how the source code got started - to show the source of the call to a toneonly pager. With a numeric or an alphanumeric display pager the source-code is notso useful since the telephone number of the calling party is displayed on the pager,or better-yet, a complete alphanumeric message tells you everything you need toknow.Function Codes for Information ServicesFor Information Services we can make very valuable use of this extra part of thecapcode as an "address code." Since the ADVISOR has a capacity of four capcodesand each capcode has four Addresses, (also called source-codes or function codes)then we can have up to sixteen different Addresses in the pager. This is great for Information Services and is exactly what we do when we set up the "Mail Drop"feature in the ADVISOR.Message Indication Type sMessages sent to the ADVISOR can be selected as individual, group, or Mail Drop. Individual messages, also called personal messages, are shown on the first line ofthe message-status screen. Group messages are indicated by a special group promptat the end of the message. Individual messages can be shown with the addressnumber if the Show-Source option is selected. Mail Drop messages are displayed onthe second line of the message-status screen.Mail DropAny of the four address codes can be selected as Mail Drop. Mail-Drop messages differ from private messages as follows:•Mail-drop messages always go into a designated slot corresponding to the "address" number, i.e. an address-two message goes into the second slot ofline two of the display•Mail Drop messages cannot be locked, they are automatically replaced by a new message•No duplication of Mail Drop messages•Mail Drop messages cannot be transferred to the History Dump File•If the "Save Mail Drops" option is selected, all Mail Drop messages will be saved in non-volatile memory.Mail Drop addresses work like they were separate capcodes. If one of the Mail Drop addresses is being used for showing the currency exchange rate, it will always have the latest information in the same message location or "slot". Imagine how confusing it would be if the exchange rate was sent out as an individual message. It would be very difficult to find which of the many messages in memory was the latest quotation. It would be necessary to read all the messages and look at the time stamp of each to determine what the latest exchange rate was. Fortunately, that is not how it works. As each new Mail Drop message comes into the pager, it replaces (erases) the previous message. All the subscriber needs to do is read the message in the "slot" on the pager screen designated for the currency exchange rate. It will always be the latest one and will always be in the same place.Paging Terminal and Mail DropsEach of the 16 possible addresses in the ADVISOR must be treated as a separate capcode in the paging terminal. This can easily be accomplished in most paging terminals. It is simply a matter of setting up four subscriber records for each capcode and programming each record for a different address (function code or source code). Please refer to the Capcode Assignment Illustration below. If the carrier is offering four information services on one capcode and a subscriber only wants to pay for three of them, then the ADVISOR can be programmed with an "X" in that slot, making that address inactive.Message StorageThe ADVISOR can store up to 20 personal messages (individual or group) that are located on the first line of the message-status screen. Newer (or unread) messages are located on the right side of the first line; older messages are located on the left side of the first line. The pager can store up to 16 Mail Drop messages that are located on the second line of the message-status. (If all 16 are used there would be no address available for personal messages.) Also, up to ten messages can be stored in the history dump file and up to ten messages in the personal message file. A single alphanumeric message can be up to 2000 characters in length, depending on system capability.Group CallsGroup calls are very effective for firemen, security personnel, and medical response teams. A cardiac-arrest-response team might be made up of several doctors and nurses each having an individual code for private messages and a group-call code for alerting them all at the same time that someone has had a heart attack.For a large-scale Information Service operation, Group Calls probably do not offer enough flexibility for long-term growth. It would be better to allocate code "C"and/or code "D" for Information Services. This will cause a minor reduction in the pager's battery life (approximately 30%), due to its operation in two different frames, but will make the assignment of the different Information Services easier.Another example: the table on the following page shows how to select a group call code and then assign ten pagers with individual codes to the group. Each pager will have an individual code for private messaging, and a group call code for messages of common interest to the whole group. This table illustrates the rule that each individual code in the group must skip eight codes in the sequence so that all the codes will be in the same frame. Another table follows on the next page, showing the same codes which were selected, but illustrating them grouped together.CAPCODE FRAME ASSIGNMENT CAPCODE FRAME ASSIGNMENT11111117Group Call11111531111111201111154211111131111115531111114211111564111111531111157511111164111115861111117511111597Individual Call111111861111160011111197Individual Call11111611111112001111162211111211111116331111122211111644111112331111165511111244111116661111125511111677Individual Call111112661111168011111277Individual Call111116911111128011111702111112911111171311111302111117241111131311111735 1111132411111746 1111133511111757Individual Call 111113461111176011111357Individual Call11111771 1111136011111782 1111137111111793 1111138211111804 1111139311111815 1111140411111826 1111141511111837Individual Call 111114261111184011111437Individual Call 11111851 1111144011111862 1111145111111873 1111146211111884 1111147311111895 1111148411111906 1111149511111917Individual Call 111115061111192011111517Individual Call11111931 1111152011111942Group Call Capcode Assignment Summary CAPCODE FRAME ASSIGNMENT CODE "A"CODE "B"11111117Group Call11111197Individual Call1111119111111111111277Individual Call1111127111111111111357Individual Call1111135111111111111437Individual Call1111143111111111111517Individual Call1111151111111111111597Individual Call1111159111111111111677Individual Call1111167111111111111757Individual Call1111175111111111111837Individual Call1111183111111111111917Individual Call11111911111111This is an illustration of the ten codes selected from above. There are ten individual codes and one common group-call code. The assignment of capcodes to Code "A" and Code "B" in the pager is also shown. All the codes are in the same POCSAG frame ( i.e. frame 7 ).Please note that according to the Coding Rules on page one, a pager programmed according to this example cannot have Codes "C" and "D" added later. Let's review the rules for four POCSAG codes in the ADVISOR:•There must be a code A•Codes A and B must be in the same frame•If there is a code D there must be a code C•Codes C and D must be in the same frame•Codes C and D cannot be in the same frame as code A•Codes C and D must be in a higher frame than codes A and BSo if there is any possibility that these users would want to subscribe to Information Services in the future, it would be better if their codes were in a frame less than frame seven. This, however, would not be a major problem since a pager can be easily reprogrammed at any time. If a carrier should want to offer eight different Information Services, on the following page there is an example of one way to program ADVISOR pagers for Individual, Group, and Information Services. An ADVISOR can only operate in two frames.Capcode Assignment IllustrationPOCSAG frames according to the last 3 digits of the 7-digit capcodeFrame0Frame1Frame2Frame3Frame4Frame5Frame6Frame7000001002003004005006007 008009010011012013014015 016017018019020021022023 024025026027028029030031 032033034035036037038039 040041042043044045046047 048049050051052053054055 056057058059060061062063 064065066067068069070071 072073074075076077078079 080081082083084085086087 088089090091092093094095 096097098099100101102103 104105106107108109110111 112113114115116117118119 120121122123124125126127 128129130131132133134135 136137138139140141142143 144145146147148149150151 152153154155156157158159 160161162163164165166167 168169170171172173174175 176177178179180181182183 184185186187188189190191 192193194195196197198199 200201202203204205206207 208209210211212213214215 216217218219220221222223 224225226227228229230231 232233234235236237238239 240241242243244245246247 248249250251252253254255256257258259260261262263 264265266267268269270271 272273274275276277278279 280281282283284285286287 288289290291292293294295 296297298299300301302303 304305306307308309310311 312313314315316317318319 320321322323324325326327 328329330331332333334335 336337338339340341342343 344345346347348349350351 352353354355356357358359 360361362363364365366367 368369370371372373374375 376377378379380381382383 384385386387388389390391 392393394395396397398399 400401402403404405406407 408409410411412413414415 416417418419420421422423 424425426427428429430431 432433434435436437438439 440441442443444445446447 448449450451452453454455 456457458459460461462463 464465466467468469470471 472473474475476477478479 480481482483484485486487 488489490491492493494495 496497498499500501502503 504505506507508509510511 512513514515516517518519520521522523524525526527 528529530531532533534535 536537538539540541542543 544545546547548549550551 552553554555556557558559 560561562563564565566567 568569570571572573574575 576577578579580581582583 584585586587588589590591 592593594595596597598599 600601602603604605606607 608609610611612613614615 616617618619620621622623 624625626627628629630631 632633634635636637638639 640641642643644645646647 648649650651652653654655 656657658659660661662663 664665666667668669670671 672673674675676677678679 680681682683684685686687 688689690691692693694695 696697698699700701702703 704705706707708709710711 712713714715716717718719 720721722723724725726727 728729730731732733734735 736737738739740741742743 744745746747748749750751 752753754755756757758759 760761762763764765766767 768769770771772773774775 776777778779780781782783784785786787788789790791 792793794795796797798799 800801802803804805806807 808809810811812813814815 816817818819820821822823 824825826827828829830831 832833834835836837838839 840841842843844845846847 848849850851852853854855 856857858859860861862863 864865866867868869870871 872873874875876877878879 880881882883884885886887 888889890891892893894895 896897898899900901902903 904905906907908909910911 912913914915916917918919 920921922923924925926927 928929930931932933934935 936937938939940941942943 944945946947948949950951 952953954955956957958959 960961962963964965966967 968969970971972973974975 976977978979980981982983 984985986987988989990991 992993994995996997998999Frame0Frame1Frame2Frame3Frame4Frame5Frame6Frame7To determine which frame a capcode is in, locate the last 3 digits of the 7 digit capcode in this table. The column will indicate the correct frame for all capcodes.。