时域波形的参数测量实验报告s

时域测试技术综合实验报告书

实验名称时域波形的参数测量实验

班级一班学号201422070125 姓名杨梅

实验时间：年月日得分：

一、实验目的

1.学习VISUAL DSP++开发流程。

2.掌握波形时域参数（周期、上升时间等）的测量方法。

3.掌握波形幅度参数（幅度、平均值、均方根值等）的测量方法。

4.掌握参数统计的一般实现方法。

二、实验内容

1.学习Visual DSP++的开发设计流程。

2.编写程序测量波形参数。

3.编写程序对波形参数进行统计运算。

三、实验步骤

1、计算并显示示波器幅度参数：平均值、有效值。打开Ypara.c源文件，填充缺少的代码。

int GetAverage(short *pBuffer, int Length)

{

int Sum=0;

int i;

for (i=0; i

{

Sum += *pBuffer;/*input your code*/

pBuffer++;

}

return Sum/Length;/*input your code*/

}

float GetRMS(short *pBuffer, int Length, int ZeroValue)

{

float Sum=0;

int i;

for (i=0; i

{

long temp;

temp =pBuffer[i] - ZeroValue;/*input your code*/

temp *= temp ;/*input your code*/

Sum += temp;

}

Sum /= Length;

return sqrt(Sum)+ZeroValue;

/*input your code*/

}

2、计算并显示示波器幅度类参数：顶值、底值。打开Ypara.c源文件，填充缺少的代码。int GetTop(short *pBuffer, int Length)

{

short midpoint, toppoint, i;

midpoint=GetAverage(pBuffer,Length);

toppoint= GetMax();

i=toppoint;

GetCount(*pBuffer, Length);

do

{

i--;

if (tmpbuffer[i]>tmpbuffer[toppoint])

toppoint=i;

}while(i>midpoint);

//修正

if (tmpbuffer[toppoint]

toppoint= GetMax();

return toppoint;/*input your code*/

//return 1;

}

int GetBase(short *pBuffer, int Length)

{

short midpoint, basepoint, i;

midpoint=GetAverage(pBuffer, Length);

basepoint= GetMin();

i=basepoint;

GetCount(*pBuffer, Length);

do

{

i++;

if (tmpbuffer[i]>tmpbuffer[basepoint])

basepoint=i;

}while(i

//修正

if (tmpbuffer[basepoint]

basepoint= GetMin();

return basepoint;

/*input your code*/

//return 1;

}

3、计算并显示示波器时间类参数：上升时间。打开Xpara.c源文件，填充缺少的代码。int GetRising(short *pBuffer, int Length, int yPer10, int yPer90, int *pxPer10, int *pxPer90) {

int Index=0;

while (Index < Length && pBuffer[Index] > yPer10 /*input your code*/ )

Index++;

while (Index < Length && pBuffer[Index] <=yPer10 /*input your code*/ ) Index++;

int xPer10=0;

if (Index < Length)

xPer10 = Index;

while (Index < Length && pBuffer[Index]

Index++;

int xPer90=0;

if (Index < Length)

xPer90 = Index;

*pxPer90 = xPer90;

*pxPer10 = xPer10;

return 1;

}

4、新建文件Statistic.c和Statistic.h，并将其加入工程中。在Statistic.c文件中对平均值和周期两个参数进行统计运算，并填写如下表格。

(1) 在Statistic.c文件中的参数统计算法：

int GetAverage(short *pBuffer, int Length)

{

int Sum=0;

int i;

for (i=0; i

{

Sum += *pBuffer;/*input your code*/

pBuffer++;

}

return Sum/Length;/*input your code*/

}

int GetPeriod(short *pBuffer, int Length, int yPer10, int yPer90, int *pxFirst, int *pxLast)

{

int FirstR10, FirstR90, FirstMid;

GetRising(pBuffer, Length, yPer10, yPer90, &FirstR10, &FirstR90);

FirstMid=(FirstR10 + FirstR90) / 2;

int FirstF10, FirstF90, SecondMid;

GetFalling(pBuffer, Length, yPer10, yPer90, &FirstF10, &FirstF90);

SecondMid=(FirstF10 + FirstF90) / 2;

int Third10, Third90, ThirdMid;

if (FirstMid > SecondMid)

{

GetFalling(pBuffer+FirstR90, Length-FirstR90, yPer10, yPer90, &Third10, &Third90);

*pxFirst= SecondMid;

ThirdMid=(Third10 + Third90) / 2 + FirstR90;

}

else

{

GetRising(pBuffer+FirstF10, Length-FirstF10, yPer10, yPer90, &Third10, &Third90);

*pxFirst= FirstMid;

ThirdMid=(Third10 + Third90) / 2 + FirstF10;

}

*pxLast = ThirdMid;

return 1;

/*input your code*/

*pxFirst= 50;

*pxLast = 100;

return 1;

}

四、实验思考题

1、如何提高波形测量的精度？

答：主要有两种方法，其一是减少测频量化误差，即增加测量时间（主门时间）的方法；其二是减小侧周量化误差，即采用多周期测量法，在这里不再赘述。此外，为了提高测量的准确度，比较常用的方法还有游标法、内插法、平均测量技术、多周期同步测量法、相检宽带测频技术以及量化时沿法。

2、完善波形周期、幅度值的测量算法。

答：int GetPeriod(short *pBuffer, int Length, int yPer10, int yPer90, int *pxFirst, int *pxLast) {

int FirstR10, FirstR90, FirstMid;

GetRising(pBuffer, Length, yPer10, yPer90, &FirstR10, &FirstR90);

FirstMid=(FirstR10 + FirstR90) / 2;

int FirstF10, FirstF90, SecondMid;

GetFalling(pBuffer, Length, yPer10, yPer90, &FirstF10, &FirstF90);

SecondMid=(FirstF10 + FirstF90) / 2;

int Third10, Third90, ThirdMid;

if (FirstMid > SecondMid)

{

GetFalling(pBuffer+FirstR90, Length-FirstR90, yPer10, yPer90, &Third10, &Third90);

*pxFirst= SecondMid;

ThirdMid=(Third10 + Third90) / 2 + FirstR90;

}

else

{

GetRising(pBuffer+FirstF10, Length-FirstF10, yPer10, yPer90, &Third10, &Third90);

*pxFirst= FirstMid;

ThirdMid=(Third10 + Third90) / 2 + FirstF10;

}

*pxLast = ThirdMid;

return 1;

/*input your code*/

*pxFirst= 50;

*pxLast = 100;

return 1;

}

int GetAmplitude(short *pBuffer, int Length)

{

return GetTop(pBuffer, Length)-GetBase(pBuffer, Length);

}

五、实验结果分析与总结

（1）系统的噪声水平、和被测信号的信噪比对波形参数测量的精度有直接的影响，通过参数统计功能可以减小噪声对参数测量的影响。

（2）脉冲波形的顶值、低值非常重要，幅度、上升时间、脉宽等其他波形参数的都依赖于顶值和低值。

（3）对正弦波、三角波而言，其顶值、低值就是最大和最小值。

【注意：每次完成实验后，按上面的格式手写并上交实验报告。】