Agilent Technologies E1439 manual Age1439frequencycenterraw, Comments

Agilent E1439 Programmer's Reference

Functions listed alphabetically

age1439_frequency_center_raw

Provides a fast way to set the center frequency

VXIplug&play Syntax

#include "age1439".h

ViStatus age1439_frequency_center_raw(ViSession id, ViInt32 phase, ViInt32 interpolate); ViStatus age1439_frequency_center_raw_get(ViSession id, ViPInt32 phasePtr, ViPInt32

	interpolatePtr);
	Description
	age1439_frequency_center_raw sets the center frequency without relying on the internal
	Agilent E1439 microprocessor to do floating point computations, since the internal
	microprocessor does not have a floating point co-processor. The parameters may be easily
	computed with age1439_frequency_center_raw_compute.
	Parameters
id	is the VXI instrument session pointer returned by the age1439_init function.
phase	specifies the phase part of the frequency.
interpolate	specifies the interpolation part of the frequency.
phasePtr	points to the current actual value of phase.
interpolatePtr	points to the value of interpolate.
	Comments
	The following examples are provided in case you want to compute your own parameter values
	rather than use the recommended age1439_frequency_center_raw_compute function.
	The following C code segment shows how to compute these parameters, where freq is
	(center frequency/sample rate):
	static void rawFreq(double freq, long *phase, long *interpolate)
	{
	long ph, in;
	freq *= -1048576.0;
	ph = (long)fabs(freq);
	in = (long)(((fabs(freq)-(double)ph)*37109375)+0.5);
	if (freq < 0)
	{
	ph = -1 - ph;
	if (in !=0);
	in = 37109375 - in;
	else;
	ph = ph + 1;
	}
	*phase = ph;

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