[Agilent] N9320B Spectrum Analizer Source (Measuring Phase Noise)

/************************************************************/
/* Measuring Phase Noise */
/* */
/* This example is for the N9320B Spectrum Analyzers */
/* */
/* This C programming example does the following. */
/* The SCPI instrument commands used are given as reference. */
/* */
/* - Opens a USB session */
/* - Clears the Analyzer */
/* - Resets the Analyzer */
/* *RST */
/* - Sets the center frequency and span */
/* SENS:FREQ:CENT 50 MHZ */
/* SENS:FREQ:SPAN 10 MHZ */
/* - Set the input port to the 50 MHz amplitude reference */
/* CAL:SOUR:STAT ON */
/* - Set the marker to the maximum peak */
/* CALC:MARK1:MAX */
/* - Activate the phase noise function */
/* CALC:MARK1:PHN ON*/
/* - Set offset to 20 kHz */
/* CALC:PHN:OFFS 20KHz */
/* - Query the phase noise */
/* CALC:MARK:PHN:Y? */
/* - Close the session */
/************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <ctype.h>
#include <string.h>
#include "visa.h"

ViSession defaultRM, viN9320B;
ViStatus errStatus;
ViChar cIdBuff[256]= {0};
char cEnter = 0;
int iResult = 0;

/*Set the input port to 50 MHz amplitude reference*/
void Route50MHzSignal()
{
	viQueryf(viN9320B, "*IDN?\n", "%t", &cIdBuff);
	/* prompt the user*/
	/* to connect the amplitude reference output to the input*/
	printf ("Connect CAL OUT to the RF IN \n");
	printf ("......Press Return to continue \n");
	scanf( "%c",&cEnter);
	/*Externally route the 50 MHz Signal*/
	viPrintf(viN9320B,"CAL:SOUR:STAT ON \n");
}

void main()
{
	/*Program Variables*/
	ViStatus viStatus = 0;
	double dMarkAmp =0.0;
	/*Open a USB session*/
	viStatus=viOpenDefaultRM(&defaultRM);
	// USB0::2391::8472::9876543210::0::INSTR --> YOUR VISA ADDRESS
	viStatus=viOpen(defaultRM,"USB0::2391::8472::9876543210::0::INSTR",VI_NULL,VI_NULL,&viN9320B);
	if(viStatus)
	{
	printf("Could not open a session to USB device!\n");
	exit(0);
	}
	/*Clear the Instrument*/
	viClear(viN9320B);

	/*Reset the Instrument*/
	viPrintf(viN9320B,"*RST\n");
	/*Display the program heading */
	printf("\n\t\t Noise Program \n\n" );
	/* Check for the instrument model number and route the 50 MHz
	signal accordingly*/
	Route50MHzSignal();
	/*Set the analyzer center frequency to 50 MHz*/
	viPrintf(viN9320B,"SENS:FREQ:CENT 50e6\n");
	/*Set the analyzer span to 10 MHz*/
	viPrintf(viN9320B,"SENS:FREQ:SPAN 10e6\n");
	/*Set the marker to the maximum peak*/
	viPrintf(viN9320B,"CALC:MARK1:MAX \n");
	 /*Activate the noise marker function.*/
	viPrintf(viN9320B,"CALC:MARK1:PHN ON \n");
	/*Set the offset to 20 kHz. This places the
	active marker two divisions to the right of the input signal.*/

	viPrintf(viN9320B,":CALC:PHN:OFFS 20KHz \n");
	/*Query and read the phase noise from the analyzer */
	viQueryf(viN9320B,":CALC:MARK:PHN:Y? \n","%lf",&dMarkAmp);
	/*Report the phase nosie */
	printf("\t Marker Amplitude =%lf dBc/Hz\n",dMarkAmp);
	/*Close the session*/
	viClose(viN9320B);
	viClose(defaultRM);
}