什么是同步检波?组织语言回答

这应该是电视机电路的一个术语！

就是利用二极管的非线性原理，同时从38Mhz的高频复合同步信号中检出6.5Mhz的伴音调频信号和31.5Mhz的图像信号，

后面的电路基本是分开进行工作的，比如音频信号，用超外差式电路进行检频，放等等！

还有同步信号，用微分电路和积分电路分离出行，场信号！

利用C语言，建立一个五个学生的信息登记表，要求有学号、姓名、和三门课的成绩

差不多的，自己修改下。

#include <stdio.h>

#include <string.h>

const int MAX_NUM = 5;

const int MAX_NAME_LEN = 127;

const int MAX_SUBJECT = 3;

const double SUBJECTS = 3.0;

typedef struct _Student

{

char szName[MAX_NAME_LEN + 1];

int nArryScore[MAX_SUBJECT];

int nSum;

double dAverage;

}Student;

void Sort(Student students[], int n)

{

Student stTmp;

int nTmp = 0;

int nPos = 0;

int nIndex = 0;

for (nPos = 0; nPos < n - 1; nPos++)

{

nTmp = nPos;

memset(&stTmp, 0, sizeof(Student));

for (nIndex = nPos + 1; nIndex < n; nIndex++)

{

if (students[nIndex].nSum > students[nTmp].nSum)

{

nTmp = nIndex;

}

}

memcpy(&stTmp, &students[nTmp], sizeof(Student));

memcpy(&students[nTmp], &students[nPos], sizeof(Student));

memcpy(&students[nPos], &stTmp, sizeof(Student));

}

}

int main (void)

{

printf(请输入五个同学三门课的成绩:\n);

Student students[MAX_NUM];

memset(students, 0, sizeof(students));

Student* pStudent = NULL;

int nCnt = 0;

int nPos = 0;

while (MAX_NUM > nCnt)

{

printf(第%d个同学的记录:, nCnt + 1);

pStudent = &students[nCnt];

scanf(%s %d %d %d, pStudent->szName,

&pStudent->nArryScore[0],

&pStudent->nArryScore[1],

&pStudent->nArryScore[2]);

for (nPos = 0; nPos < MAX_SUBJECT; nPos++)

{

pStudent->nSum += pStudent->nArryScore[nPos];

}

pStudent->dAverage = pStudent->nSum / SUBJECTS;

nCnt++;

getchar();

}

Sort(students, MAX_NUM);

printf(------------------------------------------------\n);

printf(输出排序后五个同学的三门成绩:\n);

printf(------------------------------------------------\n);

printf(排序 姓名 课1 课2 课3 总分 平均分\n);

for (nPos = 0; nPos < MAX_NUM; nPos++)

{

pStudent = &students[nPos];

printf(第%d名: %s %d %d %d %d %.2f\n, nPos + 1,

pStudent->szName,

pStudent->nArryScore[0],

pStudent->nArryScore[1],

pStudent->nArryScore[2],

pStudent->nSum,

pStudent->dAverage);

}

return 0;

}