[hpsdr] Alex Bug?

[Jeremy McDermond]

On Sep 1, 2011, at 1:49 PM, Scott Cowling wrote:

> ***** High Performance Software Defined Radio Discussion List *****
> 
> The firmware in Mercury selects the filter based on the frequency.
> 
> According to the comments in the code, the frequency sent to Mercury by PowerSDR is "the indicated frequency less the 9kHz IF". As a consequence, the firmware adds 9kHz to the frequency to determine which filter to engage.

I guess I'm lost a little here... what 9kHz IF?

> If GHPSDR does not do the same, then the switch points will be different.
> 
> Here are the switch points for the current Mercury code:
> 
> if
> freq > 29700000 then use 6m LPF
> else if
> freq > 21450000 then use 12/10m LPF
> else if
> freq > 14350000 then so use 17/15m LPF
> else if
> freq > 7300000 then use 30/20m LPF
> else if
> freq > 4000000 then use 60/40m LPF
> else if
> freq > 2000000 then use 80m LPF
> else
> use 160m LPF
> 
> where "freq" is the frequency data (in Hz) + 9000 for IF correction.
> 
> If GHPSDR sends the real frequency (instead of the frequency including IF offset), then these switch points would all be 9 kHz lower on your GHPSDR dial.
> 
> If your tuning step was 1kHz, it would change filters between 1,991,000 Hz and 1,992,000 Hz, so it would look like a switch point of 1992kHz.
> 
> 73,
> Scotty WA2DFI

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




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