Re: [Discuss-gnuradio] 2 RTL-SDR dongles at the same time with GRC

[Marcus D. Leech]

On 08/23/2012 05:51 PM, Alberto Trentadue wrote:
> Hello
>
> I am considering using 2 RTL SDR compliant dongles + GRC for some simple 
> interferometric application.
> Having two
> of such dongles, does anybody know if it is possible to have both running as 
> GRC sources?
> If not, would it be possible
> in theory (to be developed) or there is a strict architectural reason 
> preventing this?
>
> Thanks in advance
> Alberto
Assuming that you're using the gr-osmosdr source block, you can specify 
multiple devices:

rtl=0
rtl=1

And so on.

But be aware, there's no way to identify a "specific" RTL device -- 
those numbers just mean "the first one that enumerated this time,
  the second one that enumerated, etc".  For you application it may not 
matter whether you know on any given run which one is
  which.

Also, unless you can find a way to:

    (A)  Synchronize the reference clocks for the two RTL-SDR dongles 
(relatively easy using a shared 28.8MHz oscillator)
    (B)  Synchronize the sample stream (HARD!)

You aren't going to have much fun with interferometry.




--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org