[hpsdr] Hermes Pure Signal

[Warren C. Pratt]

Hi Lyle,

Yes, lower rates than 384K can be used.  The optimized rate today is 
192K which means we can run five simultaneous receivers within the 
100Mbit ethernet bandwidth.

On related matters, the filtering Helmut mentioned was really tightening 
of the specifications on passband ripple and other items on the DUC and 
DDC filter designs.  As you probably know, making better digital filters 
consumes more logic elements.  The other firmware item is that, during 
transmit, we pipe the DUC output back down through a DDC channel --- 
there's some switching and lines required for that.  I see Joe has 
commented on some of this in an email that I just received as I was 
composing this one.

Joe and Phil are the experts on "what will fit" and "what will not 
fit".  We've also discussed the possibility of short-circuiting the 
DUC-DDC loopback.  However, after a couple attempts, we've never made 
that work in an acceptable manner --- there's still hope; but, nothing 
proven on that path.

Finally, there's the matter of firmware development resources.  I don't 
fall into that category; however, both Joe and Phil spend a LOT of time 
on firmware.  Right now there are a lot of forward-looking efforts on 
the table and resources are scarce.

73,
Warren  NR0V