5641R FM-Demod Regeneration

[TimS.]

Hello,

I've been slowly modifying the 5641R FM-Demod example, from the RF communications library, into an FM-Demod/Regen example. I essentially want to use the 5641R as a retransmitter with processing. I've successfully used the 5641R as a retransmitter without processing but I noticed that the retransmission of an FM-Demoded signal isn't as expected. Mainly because the output of the FM-Demod IP core is real valued and the D/A on the 5641R is configured for quadrature I/Q mode. So, Do I need to add another processing loop in order to recreate IQ data and if so...how? I'm familiar with the concept of IQ and how to generate it but I'm fairly new to FPGA development as well as Fixed Point so I haven't been able to figure out how to accomplish it on the FPGA. Is there some sort of "MT Upconvert baseband to IQ" block for the FPGA?

Right now I'm essentially getting duplicated spectrum when regenerating the FM-demoded samples. For example, a 4fsk signal becomes 2 tones mirrored on either side of the IF center frequency instead of 4 independent tones.

I've attached a snippet of the code below.

Regards,

Tim S.

[Doug_L._Bear]

The 5641R (and other IF-RIO devices) are specifically supported on another forum listed below.

http://forums.ni.com/ni/board?board.id=ifrio

We have specific IF-RIO people who monitor this forum and can ensure you get an adequate answer.