Re: [Discuss-gnuradio] BasicRX boards and AM transmission

[Martin Dvh]

Don Ward wrote:
> "Philip Heron" <address@hidden> wrote:
> 
>> Martin Braun wrote:
>>> RXing with the USRP simply doesn't work, though, neither with
>>> usrp_rx_nogui.py nor with anything I could come up with. I get lots
>>> more noise than expected and usually I get a very loud buzz or
>>> whistle which is a lot louder than the TXed signal. Has anyone else
>>> had this problem?
>>
>> Hi Martin,
>>
>> Just a quick "me too!". I don't have a USRP yet but I did try using
>> GNU Radio to receive AM radio signals with a BT878 chip. With a
>> slightly modified am_rcv.py I could hear the station, but it was very
>> weak and drowned out by lots of noise. The capture was fine as I was
>> able to get good audio (as good as AM can be anyway) with the Dream
>> DRM receiver in analogue mode, using GNU Radio to shift the target
>> carrier down to 12kHz.
>>
>> -Phil
> 
> I don't think it is the USRP and I don't think it is anything inherent
> in GNU Radio.  I have been using the USRP (with LFRX) and GNU Radio for
> HF/MF/LF reception for a while now with great success.  My recollection
> is that am_rcv.py had some problems (e.g., specifying the if_rate in the
> design of the audio filter); I have not looked at usrp_rx_nogui.py.
> 
> Unless your hardware is broken, I'll bet you can find a remedy in the
> software.
> 
> -- Don W.
Hi all,

I advise to try hf_explorer or hfradio in the gnuradio-example/apps folder.

For experimenting with am reception I just added an usrp_am_mw_rcv.py example 
script in the style of usrp_wfm_rcv.py to svn.
You can find it at:
http://gnuradio.org/trac/browser/gnuradio/trunk/gnuradio-examples/python/usrp/usrp_am_mw_rcv.py

Or by just updating your subversion checkout.

It is nothing fancy.
But this is good I think for understanding the script and settings used.

No AGC is implemented (for that see usrp_rx_nogui.py or hf_radio or hf_explorer)
This means you have to adjust the volume for very strong, and  very weaks 
stations.
If you have the volume set too high, the output will clip, and you hear nothing 
or just crackles.

It does however seem to work on both strong and relatively weak stations.
(You do need to have an antenna usable for MW connected to your basic_RX, input 
RX-A. Try the longest wire you can find or better, build a loop
antenna)


Greetings,
Martin Dudok van Heel





> 
> 
> 
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>