Ni USRP-2920 FSK Demodulation

[jedome]

I am using the NI USRP-2920 to demodulate FSK, but I am unable to successfully demodulate what the radio is transmitting. The issue did not arise when I TX from USRP to USRP.

After some investigation I found the coerced data rate(coerced IQ rate divided by samples/symbol) is 320.5kbps, which is .5kbps off of my desired 320. I believe this is the issue but I don't see how to fix it.

I am already oversampling, and it appears I am at the 'sweet spot', in terms of my desired data rate. Since my IQ rate is not an even integer multiple I thought I might see some of the proper data if I have my output bit stream oversampled. I still do not see the data correctly.

I can upload code if necessary, but I thought it might not be, with the general nature of the question.

Thanks

[jedome]

Note:

The IQ rate is set at 8.32Mbps, Samples per symbol is set to 26, the coerced IQ rate comes out to be 320.5...kbps.

I started from the base niUSRP EX FSK RX.vi found on the NI website. I suppose its probably easiest to attach what I have, so here it is.... 

[replyall_ia]

Hey Jedome,

I took a look at your code and it looks like you're using ModToolkit. What's the "incorrect behavior" that you're seeing? Is it throwing an error? 

Also, don't worry about the data rate. Sure, the numbers don't match, but those numbers are still integers. Should affect anything. Also, did you run just the example without altering it? Did that work?

Thanks,

Aulia

[jedome]

I believe there were too separate issues when using different sources. When I was receiving from a radio, it appears that the data being transmitted was not configured with the proper frequency deviation(operator error).

However, I still have issues occasionally when I transmit to the USRP from the USRP TX port. I am not receiving the same data that I am transmitting. Is it is possible that I could have issues because I am trying to utilize the same USRP for both rx and tx simultaneously?

[El_Markador]

Hi jedome,

How different is the data you are receiving–or what exactly are you seeing differently? Can you post screenshots? You also said that it happens occasionally. How often is that? Assuming your configuration is sound, there shouldn't be any issues with transmitting and receiving on the same device that would result in bad data, but maybe there is something we're not seeing here.

[jedome]

I am not sure why I was seeing problems USRP to USRP. I haven't been able to spend more time on that issue, but I am able to receive perfectly any data that is transmitted to me from an additional source. This is my actual application so I have no need to further investigate.