RF Measurement Devices
PXI 5660 Zero Span Max hold Peak search function?
We have the NI PXI 5660 hardware and I found the VI at the link below which was very useful and has helped a lot but on top of what this VI does I would like to do a max hold/peak search because the PA we are measuring from is bursting not a CW output.
http://digital.ni.com/public.nsf/allkb/1810972B1F0AE6C8862574DA00482B0F
I can’t find any way to do a Peak Search or Max Hold kind of function and add it on to the Zero Span example, when we use the “Read Averaged Power Spectrum” type method we can do a peak search as below.
The zero span example uses a “Read IQ” then get magnitude of the IQ envelope type method, see below, can we do the peak search and max hold on this output? Do you know of any way to do a Max Hold/ Peak Search in a Zero Span measurement on the PXI 5660 hardware?
Perhaps there is a way to get the Graph display in the example vi to persist so that all the burst captures are overlaid on the same graph, this might be enough for now? Many Thanks in advance for your help.
Regards
Matt
Hi Matt,
Thank you for contacting National Instruments.
The 5600, has no onboard signal processing, and the data that is acquired is IF data, and the device can be configured for IQ data or for spectrum analysis.
The Zero-span vi example shown, has configured the device for IQ measurements, allowing Zero span measurements to be taken.
For Peak Search, the data of the spectrum needs to be known first. Therefore either taking measurements of IQ, followed by measurements of spectrum (not ideal) could be done, or by using software analysis to convert to Spectrum data.
1) As you can see from the attached.. The following vi can be used for Peak search seperately to the Zero-span vi. Hopefully from this, you can see how the two devices are configured differently. This vi is taken from the LabVIEW example finder.
2) If you have the Spectral measurements toolkit installed, you maybe able to use the IQ value data, and perform a FFT on the signal, allowing for a Peak search to be done.
A similar example of this can be seen in the following forum (http://forums.ni.com/ni/board/message?board.id=270&message.id=3316&requireLogin=False), and using the Zoom FFT vi's.
With regards to plotting each burst ontop of each other, I have created some example code which should explain this.
I have used a random number generator in a for loop to create my Y value array. However in your instance, you should replace this with the Y values that are being generated.
The code essentially creates a seperate channel each time the loop iterates.
Please let me know your thoughts.
