[hpsdr] Hermes Diversity

[Hermann]

I'll take the opportunity to jump in here and point to a protocol which is
a) faster than TCP and has b) a controllable reliability:

http://udt.sourceforge.net/

which could improve the situation on the ethernet significantly!

(this post is by no means mentioned to correct you, Jeremy!)

Herzliche Grüße / Kind regards

Hermann von Hasseln

DL3HVH


On Tue, Feb 8, 2011 at 1:14 PM, Jeremy McDermond <mcdermj at xenotropic.com>wrote:

> ***** High Performance Software Defined Radio Discussion List *****
>
> 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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