[hpsdr] Hermes Diversity

[Jeremy McDermond]

On Feb 7, 2011, at 5:00 PM, FRANCIS CARCIA wrote:

> ***** High Performance Software Defined Radio Discussion List *****
> 
> hi all,
> I wonder if it would be possible to have a sync pulse between two Hermes modules to act as a time tag allowing a diversity mode? Frank WA1GFZ

Joe and I have had some back-and-forths on this.  It's not really possible with the current software.  The issue is correlating the two signals when they get to the computer.  On an Atlas bus, the samples from each Mercury are interleaved in the packet that you receive from Metis (or Ozy for that matter).  When you start talking about separate Hermes boxes, you don't really know what the relationship of the samples are.  The Ethernet doesn't guarantee delivery let alone timely delivery.  Joe and I had some "pie in the sky" discussions a few months back about timestamping the packets from each Hermes to try to correlate them, but it wasn't anything concrete.

Your sync pulse idea might work if the transport between Hermes and the computer had some sort of timing guarantee.  As I said before, Ethernet has no such guarantees, and in fact it's worse than that.  Ethernet doesn't even assure that your packets will arrive at their destination.

I'm sure that I'll be immediately corrected by the guys who are 10x smarter than I am about this stuff.  I'm just an idiot wannabe-lawyer.

--
Jeremy McDermond (NH6Z)
Xenotropic Systems
mcdermj at xenotropic.com




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