Re: [Discuss-gnuradio] USRP2 + WBX: Unable to receive FM signals

[Elvis Dowson]

Hi Scott,

On Jul 16, 2010, at 7:52 PM, Scott Johnston wrote:

> I have been following this thread because I am attempting to do the same 
> thing. Can you tell me what the values for "interp" and "decim" are when the 
> program is working correctly. Also, my system is failing to tune to the 
> center frequency.  Have you come across this problem, or do you have any 
> solutions to it?

Join the club!! :-) This thing requires some heavy perseverance !! 

So, if you apply the patch that I sent across earlier, and the rational 
resampler input settings is at 32050, and the output rate setting is at 48000. 

I have attached the full file below.

usrp2_wfm_rr_rcv.py
Description: Text Data

I just changed my USRP2 driver environment to use the new UHD driver, and so 
can't run it right now, to tell you the interp and decim values. That would get 
precomputed depending upon the settings for the rational resampler input and 
output rates. 

I'm just waiting for some one to reply with a sample UHD example, so that I can 
convert the attached program to one that works with the gr-uhd driver, instead 
of the existing gr-usrp2 driver. 

The FM reception came out crystal clear, only once, with very few S's and no 
audio under-runs (aU)

All the other attempts, there was a lot of distortion and audio under-runs. 

You should use a really long piece of wire connected to the inner connector of 
the RX2 port of the WBX daughter card, via the SMA F connector that comes out 
in front. 

Also set the volume (0.0) and gain sliders to max (31.5db)

I also observed that of all the possible FM stations, I only got one with 
sufficient clarity, and all the others were garbled. Not sure if this has 
something to do with tuning to the center frequency.

Best regards,

Elvis