Re: [Discuss-gnuradio] AO-51 and GRC

[Alexandru Csete]

2009/12/8 Craig Kief <address@hidden>
>
> I need a little help.  I want to do a project involving GRC.  There is a 
> satellite called AO-51 (http://www.amsat.org/amsat-new/echo/).  If you
>
> watch some of the youtube videos you will see what most folks are using this 
> satellite for.  It is great for using HAM licenses to do
>
> audio repeaters.  I want to do this 
> (http://www.youtube.com/watch?v=1HfvmU_utI8) with SDR.  We have our ground 
> station set up where we use nova software to drive our G5500
>
> rotators.  We have a 144MHz antenna for TX and a 2.4GHz antenna for receive.  
> We have a USRP-1 with a BasicTX and DBSRX for transmit and receive.    We are 
> using
>
> the GRC for our design work.  What I want to do is be  able to talk through a 
> microphone and listen with a pc speaker on the
>
> rx side.  My  problem is that I am very new to GRC and am not positive about 
> what blocks to use and what settings I should choose.
>
> Has anyone ever tried to do anything with AO-51 and GRC?
>
> Craig

Hi Craig,

I'm playing with GNU Radio and USRP for using it as ham radio
transceiver, though I'm still learning.

Since AO-51 is an FM satellite it is relatively easy to have a quick
prototype up and running because there are already FM modulator and
demodulator blocks available in GNU Radio and GRC. There are even
examples for how to make FM transmitter and receiver in
/usr/share/gnuradio/examples/usrp/ or
/usr/share/gnuradio/examples/grc/usrp/ for GRC. For GRC I can only
find wide band FM receiver example, but you can simply replace the
wide band FM demodulator block with a narrow FM demodulator.

I don't know how good DBSRX is above 2.4 GHz, I have only used it on
2.2 GHz where it works very well. Otherwise there is the RFX2400 for
2.3-2.9 GHz. Note the AO-51 is very often in V/U mode, i.e. uplink on
145 MHz and downlink on 435 MHz and the DBSRX will not cover that.

Cheers

Alex