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Chapter 3 131
Programming Examples
Using Markers
while (!lComplete)
viScanf (viVSA,"%d",&lComplete);
/*assign marker 1 to the average trace of the spectrum*/
viPrintf(viVSA, "CALC:SPEC:MARK1:TRAC ASP\n");
/*put the marker 1 on the signal peak*/
viPrintf(viVSA, "CALC:SPEC:MARK1:MAX\n");
/*query the 50 MHz signal amplitude*/
viPrintf(viVSA, "CALC:SPEC:MARK1:Y?\n");
/*get the the 50 MHz signal amplitude*/
viScanf (viVSA,"%lf",&dPeakPower);
/*assign marker 2 to the average trace of the spectrum*/
viPrintf(viVSA, "CALC:SPEC:MARK2:TRAC ASP\n");
/*assign the marker function NOISE to marker 2 */
viPrintf(viVSA, "CALC:SPEC:MARK2:FUNC NOISE\n");
/*position marker 2 on the noise floor*/
viPrintf(viVSA, "CALC:SPEC:MARK2:X 50.2E6\n");
/*query NOISE marker*/
viPrintf(viVSA, "CALC:SPEC:MARK2:FUNC:RES?\n");
/*get the the NOISE marker reading*/
viScanf (viVSA,"%lf",&dNoiseMarker);
/*put the analyzer back to continuous mode*/
viPrintf(viVSA, "INIT:CONT 1\n");
/*calculate the difference between the marker peak and the NOISE marker*/
dResult = fabs(dNoiseMarker - dPeakPower);
/*print result to the standart output*/
printf("The Peak Marker measured = %.2lf dBm\n",dPeakPower);
printf("The Noise Marker at 50.2 MHz measured = %.2lf dBm/Hz\n",dNoiseMarker);
printf("The difference between the Peak and the Noise Floor = %.2lf
dBc/Hz\n\n",dResult);
/* close session */
viClose (viVSA);
viClose (defaultRM);
}