RFSG Dynamic Frequency Change

[jstarustka]

I am trying to mimic a TDMA/FDMA system using the RFSG and the modulation toolkit.  I am using the script triggering function to mimic the TDMA portion of the system but I am having problems with the FDMA side.  I need the RFSG to switch frequencies within a 90ms TDMA frame multiple times.  My question is can the PXI-5610 and PXI-5441 change frequencies dynamically like this and if so how?  Also if this is possible what type of delay would I be looking at.

Thanks

Joe

[Andy_Hinde]

Hi Joe,
The tuning speed specifications are listed in the product specs for the PXI-5670/PXI-5671, and are from 10-30 ms.

If the frequencies you are trying to switch between are within a 20 MHz span of frequencies there may be a way to workaround this. Also what generator are you using? A PXI-5670 or PXI-5671?

Regards,
Andy Hinde
National Instruments

[jstarustka]

Thanks for the quick response. We have the PXI-5671.  I can work with the 10-30ms tuning time.  Also on the RX side I will also have to change frequencies within a 90ms frame we have the PXI-5600 and PXI-5142 Downconverter package.  I am hoping that this is possible and if so how do I do it in Labview.

Thanks

Joe

[Matt_A]

Hello Joe,

The PXI-5600 and the PXI-5142 pair to form the PXI-5661 Vector Signal Analyzer. The NI PXI-5661 Specifications are online here and contain specifications for the tuning speed for both the downconverter and the digitizer. These specifications are as follows:



For an example of how to change frequencies on the fly I would recommend that you examine an example program. You can find the NI Example Finder by going to Help>>Find Examples... in LabVIEW. Once you have opened the NI Example Finder, you can navigate to NI-RFSA examples by selecting Hardware Input and Output>>Modular Instruments>>NI-RFSA (RF Signal Analyzer). Specifically, I would recommend that you look at the example called RFSA Frequency Sweep.vi in the Frequency Domain Analysis Folder. As described in the help:

"This example shows how to configure NI-RFSA for spectrum acquisition, how to set the resolution bandwidth and reference level, and how to read power spectra while changing the center frequency in each iteration of the sweep and keeping the span constant. The spectrum is displayed on the graph. Note: This example illustrates how to perform multiple spectrum acquisitions with different center frequency values."

The example uses the Center Frequency property to set the center frequency, in Hertz, of the spectrum analyzer.

Message Edited by Matt A on 08-23-2007 02:40 PM