Re: [Discuss-gnuradio] Merge multiple complex streams

[Martin Braun]

On 12.05.2014 17:49, Imre Biacsics wrote:
> Playing around with GRC for a few months now, sorry if this question is
> from a dummy.
>
> I've a bunch of rtl dongles laying around, and wonder if it's possible to
> combine more then one to a single baseband signal.
>
> The goal is to create a super cheap full HF band web reciever like or for
> ' websdr'
>
> I managed to create multiple channels, where the 2nd dongle is tuned to an
> offset, equal to the samplerate of the first. (for example 2 x 2 Msps = 4
> Msps baseband)
>
> Is such a thing possible with GRC?

A couple of things, on top of what Mike said:

- HF bands go lower than the frequency of the dongles. Keep that in mind.
- As Mike said, clocks aren't sync'd. So, if you're using data from 
multiple dongles, that'll most likely be corrupt.
- To make things worse, they drift differently too. So, little chance in 
fixing things.
- If all you want is an (inaccurate) "spectrum analyzer" for more than 2 
MHz, then this is actually not a bad idea. If you have N+1 dongles, you 
can use N of them to monitor N*2MHz of spectrum, and the other one to 
receive at frequencies you're interested in.

M