Multi input Multi Output

[Kalash]

Hello,

I work with NI PXIe-5652 in MultiChannel, module for RF application with 6.6Frequency stop and I wanted to know a little thing about this. (DataSheet : http://www.ni.com/pdf/manuals/373158b.pdf)

I saw that modules are connected with a master and three slaves.

When i work in a channel, can i use whatever channel or just the master ? ( for one measurement )

I have a problem too. When i run 2 channels at the same time (The master and the 1st slave), the power that i analyze in my slave lose 30 dbm (I give -10dBm and i see -40dBm in analyzer) . Do you know why ?

Thanks for you help

[mbb25]

If you are just doing one measurement (single input or output), just using the master is simpler.  This is because the RFSG or RFSA session for the master device will control the LO.  If you must use one of the slave devices for a single measurement, you need to open a separate session to the 5652 LO, and set the frequency and power as appropriate.  You may need to also enable LO Out on the devices in the LO daisy-chain up to the slave device you are using.  If LO Out was enabled on these devices the last time you used them, this step should not be necessary.

I don't know why you'd loose 30 dB on the slave analyzer.  Two ideas come to mind:

   1)You don't have the LO signal properly daisy-chained from the master to the slave, or

   2) Perhaps there is a problem with this particular 5601

You could try configuring the slave device that is having trouble as a master device.  If that works, the 5601 is fine and your problem is likely something similar to #1.  A simple way to check this (without needing to rearrange all the modules) is to use a normal SMA cable for the LO signal rather than the semi-rigid ones that come in the MIMO test kit.  With a normal SMA cable, you can connect the 5652 RF Out to LO In on any of the 5601 devices in your system.  Just make sure to go back into MAX and tell it which 5601 has the 5652 connected (right-click the 5601->properties).  If you use PXI_Clk as the reference clock, then you don't have to bother re-arranging the reference clock cabling.

[Andy_Hinde]

Hi Kalash,

All the NI-RFSA shipping examples and the NI-RFSA Soft Front Panel (SFP) will work for the master channel of your setup, but will not work for any of the slaves.

If the power being read by the first slave is 30 dBm lower than the power being measured by the master, I would first check signal connections and cables. You want to make sure you are getting ~0 dBm at LO IN of the slave 5601. Check the RF IN connector on the 5601 for damage as well, particularly the inner conductor. You can try swapping the 5601/5622 modules that are part of the 1st slave channel with others to see if the problem goes away. Also, check the temperature value being measured for the 1st slave 5601 by going to MAX and looking at the Calibration data for the module.

Regards,

Andy Hinde

RF Systems Engineer

National Instruments

[Kalash]

Thanks for your help.

Indeed i saw that yesterday and i find that i have to put teh LO enabled.

Thanks for your answers and this explanations

Regards

[Andy_Hinde]

Hi Kalesh,

The 5601 LO OUT terminal is always enabled.You cannot disable the exporting of the LO on the PXIe-5601 downconverter that is part of the PXIe-5663E analyzer. When not using the LO OUT signal (like on the last channel of your phase-coherent setup) you should remember to use the 50 ohm terminator that comes with the 5601 module on the LO OUT terminal.

There is an attribute in NI-RFSA 2.4 and later for LO Export Enabled, but this applies to the PXIe-5665 analyer, which uses the PXIe-5603 RF downconverter. This downconverter does allow the user the option to toggle the LO OUT exporting in software.

If you wire a FALSE to LO Export Enabled for your 5663E devices, you will receive an error. If you wire a TRUE value to this attribute, you will not receive an error, since it is always exported.

Of course, you never state in your original post whether you are working with analyzers (PXIe-5663E) or generators (PXIe-5673E). If your issue is with signal generators, then exporting the LO via the NI-RFSG property node will indeed solve your problem....

Regards,

Andy Hinde

RF Systems Engineer

National Instrumemnts