Re: [Discuss-gnuradio] Fw: Need Advice for SDR choice

[Mark J. Blair]

On Jan 2, 2011, at 1:31 PM, Andrew Rich wrote:
> I have a MacBook PRO I7 it can run OS X or windows

I have been successfully using the Ettus Research USRP with LFRX, LFTX and WBX 
boards on my 17" MacBook Pro under OS X (Snow Leopard). Installing the software 
portion is pretty easy: Install the MacPorts package, then run "sudo port 
install gnuradio" in a terminal window. You can play with the gnuradio software 
to see if it's right for you before committing to buying any hardware, since it 
can use the audio device and/or data files as a source/sink, or even run 
entirely simulated flowgraphs.

I haven't used any gnuradio-based canned ham radio USB/LSB/whatever 
applications (if any exist). I have successfully received 2m FM transmissions 
with one of the examples that comes with the gnuradio distribution. I've mostly 
used my hardware to generate fairly simple test signals for other radio 
hardware (i.e., a number of simultaneous CW tones within a fairly narrow 
bandwidth) and simple spectrum analysis. At the moment, I'm playing around with 
writing blocks and flowgraphs for sending and receiving high-speed Morse code, 
due to my current interest in devices such as the AN/GRA-71 code burst keyer 
(*). This is all pretty simple stuff that the USRP hardware is overkill for, 
but I'm just beginning to learn about gnuradio and SDR design in general.

Based on what you've stated so far, I think that a USB-based USRP with a WBX 
board and the gnuradio software should work nicely for you, and you can work 
with it directly under OS X. You may also want to get an RFX2400 board to hit 
the 2.4GHz band (I have one, but haven't done much with it yet). This board 
combination will leave a hole between 2.2GHz and 2.3GHz.

If I recall correctly, I've generally set my hardware decimation to limit 
sampled bandwidth to about 2 MHz in order to avoid USB over-runs and/or 
under-runs. I've been able to look at a 4 MHz bandwidth with occasional 
over/under-runs. The occasional over/under-run doesn't seem to cause problems 
when just visually watching an FFT plot (i.e., to look for activity within a 
band).

I don't know if the Ethernet-based USRP platforms work on Macs yet.




(*) More info here if you're curious:

    http://www.militaryradio.com/spyradio/gra71.html

These are available (though rare) on the surplus market, but I'm unaware of any 
of the original receiving equipment that has made it out to the hands of 
collectors. A SDR setup seems like a natural way to handle receiving the code 
burst and then either playing it back at low speed for manual decoding, or 
automatically decoding the transmission at normal speed.

-- 
Mark J. Blair, NF6X <address@hidden>
Web page: http://www.nf6x.net/
GnuPG public key available from my web page.