Downconverting with PXI 5600

[eBuddy]

hi...

I am using PXI-5610 and PXI-5600 modules as separate upconverter and downconverter respectively. I have a 20 MHz centered IF signal which i upconverted with PXI-5610 and then that upconverted signal is fed to PXI-5600 for downconversion. I got the downconverted signal but the center frequency signal is 10 MHz which i expect 20 MHz. I tried to increase my IF frequency. When I used 26 MHz centered IF frequency after upconver and downconverter process I get 16 MHz at downconverter output.

I am using Labview niRFSA example code. Why am I not getting the IF frequency on which the IF signal was upconverted originally? Can I set the center frequency of the downconverter???

[eBuddy]

Can anyone help me with this???

I tried to give different frequencies from 20 MHz to 30 MHz to the input of upconverter and the output of upconverter PXI 5610 connected to the input of downconverter PXI 5600. In all case i got 10 MHz less frequency at the output of downconverter, i.e if i give 22 MHz input to upconverter, at the output of downconverter I get 12 MHz and if i give 29 MHz then i get 19 MHz at the output of downconverter.

In one document I read that PXI 5600 always give output on center frequency 15 MHz, which I am not getting. Can anyone explain me what I am getting is right or not? Do I need to use any setting for that?

I need to further demodulate this downconverted signal, untill I am clear with the downconverter output i am not able to proceed with the demodulation logic development.

Kindly help... Thanks....