if you are trying to process ADS-B from two different dongles, running two dump1090's isn't a problem. i routinely run dump1090 and rtl_acars using two dongles on the same machine simultaneously. when running two dump1090 process you must provide the device id for each and make sure both aren't running their web servers on the same port.

a more useful setup is to have multiple receivers running on cheap servers (e.g. raspberry pi) at different locations and then collecting and correlating the data.  having receivers at different locations should yield a larger coverage area.


On Sun, Aug 25, 2013 at 7:13 AM, Jiao Xianjun <putaoshu@gmail.com> wrote:
basically you are right.
But there is signal processing algorithm to track two dongles sampling/oscillator error separately and compensate them separately. Thus we can get them synchronized finally after signal processing algorithm.

What I need actually is that how to get two streams of sample from two dongles.

Actually I notice that in dump1090 it put rtlsdr_read_async in a new created background thread, then there is a possibility that I create two thread to operate two dongles. But in this method, there should be some mechanisms to synchronize two threads. It is complicated.

Anyone has simpler solution?

Thank you.



On Sun, Aug 25, 2013 at 9:49 PM, Thierry Leconte <thierry.leconte@laposte.net> wrote:
Le 25/08/2013 15:13, Jiao Xianjun a écrit :

Hi,

I want to use multiple rtl-sdr dongles to do some multi-antenna experiments.

Is it possible to read IQ samples from multiple rtl-sdr dongles in a synchronized manner?

Each dongle have its own clock, so it will never be synchronized at the sample level.