Stanford Research Systems SR844, Руководство пользователя

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Example Program 4-41
SR844 RF Lock-In Amplifier
// ************************************************************************
void GetSpace (void) {
// Wait for space bar pressed.
char ch;
while ( kbhit() ) getch(); // Clear keyboard buffer.
printf ("\n<Space> to continue, <Q> to quit >");
do {
ch = (char) getch();
if ( (ch=='q')||(ch=='Q') ) exit(0);
// exit
}
while (ch != ' ');
// Until space bar
printf ("\n");
}
// ************************************************************************
double xBin (int quant, int index)
{
// Returns double result from FAST mode array (integer X and Y data).
// See FAST command description for more details.
// quant selects X, Y, R or Phase to be returned
double x,y;
x = (double)FastBuf[2*index]/29788.0; // 29788 is full scale
y = (double)FastBuf[2*index+1]/29788.0;
x = x * fscale[sens]; // CONVERT to voltage
y = y * fscale[sens]; // by multiplying by full scale input voltage.
switch (quant) {
case 1: return (sqrt(x*x + y*y)); // Compute R from X and Y
case 2: return (atan2(y,x) * 57.2958); // Compute theta from X and Y
case 3: return (x);
case 4: return (y);
default: return (0.0);
}
}
// ************************************************************************
double xLIA (int chan, int index)
{
// Returns double result from LIA float arrays.
// See TRCL command description for more details.
int mant,exp;
double val;
if ( chan==1 ) { // channel 1
mant = rLiaBuf[2*index]; // First comes the mantissa (16 bits)
exp = rLiaBuf[2*index+1] - 124; // Then the binary exponent (16 bits)
// offset by 124
val = (double) mant * pow(2.0,(double) exp);
}
if ( chan==2 ) { // channel 2
mant = pLiaBuf[2*index]; // First comes the mantissa (16 bits)
exp = pLiaBuf[2*index+1] - 124; // Then the binary exponent (16 bits)
// offset by 124
val = (double) mant * pow(2.0,(double) exp);
}
return (val);
}
// ************************************************************************