[hpsdr] How many RX channels supported by Hermes Protocol_1 384ksps ?

[Joe Martin]

Tom, 

Hermes v3.2 firmware supports 4 receivers.  This issue isn’t room in the FPGA especially as it is currently about 80% full.  The issue is that at the 384ksps sampling rate the resulting data rate for four receivers running on the ethernet connection is a bit more (due to packet overhead) than:

384,000 samples per sec x 24 bits per sample x ( 1 I sample + 1 Q sample) x 4 receivers = 73.728 M bits per sec ,

so at 74Mbps there’s not too much data rate room left on the (100Mbps) 100Tconnection for additional receivers.  Some room left but not much.  

73, Joe K5SO


> On May 8, 2017, at 8:52 PM, Tom McDermott <tom.n5eg at gmail.com> wrote:
> 
> ***** High Performance Software Defined Radio Discussion List *****
> 
> 
> I've been asked by some researchers to increase the number of receivers supported
> by the Hermes gnuradio drivers. I recall that the Hermes FPGA has some space
> limitations in Protocol_1 that limit the number of receivers that can be implemented.
> 
> Could anyone advise me as to what the maximum number of receivers at 384 ksps
> sampling rate are available in Hermes / most recent version of the Protocol_1 firmware ?
> (I think it's V3.2).
> 
> 
> -- Tom, N5EG
> 
> 
> 
> 
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