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psa e444x trace data both y and x

Question asked by jbostak on Dec 19, 2017

Hi PSA users:


I am using a PSA E444X spectrum analyzer.  I can use TRAC:DATA?  TRACE 1 to query the trace data.  This returns the y data, i.e. the amplitude data.  I also need the x data, i.e. the frequency points which accompany each amplitude point.  I tried to generate my own vector of x data based on center frequency and span, but this is where the difficulties arose.  Although I set start frequency = 50 kHz, and stop frequency = 1050 kHz, in fact I noticed on the spectrum analyzer that the start frequency actually got set to 37 kHz.  I query the start and stop frequency over GPIB, and the PSA responds with 50 and 1050 kHz, respectively, but this is not what is shown on the screen. When I move the marker to the far left of the screen, it starts at 37 kHz.


Since in general, I am programming remotely, I don't have the opportunity to notice that the actual start frequency is not the start frequency which I requested in my command.  Then, when I plot the results of the TRAC:DATA?  TRACE 1 command, I assume the wrong start frequency, and all of my frequency data is off, sometimes by as much as 10% in frequency.  Does anyone have a solution to this problem?