I finally installed a M-Audio Audiophile 192 sound-card on my F14 system
today, further to my efforts to make
a WWVB (and DCF77 and any other time station that uses
broadly-similar mechanisms) receiver based on
little more than a high-rate sound-card, pre-amp, and loop antenna
(and of course, Gnu Radio).
I have a similar set-up for doing SID detection on VLF, using an
external 96KHz USB sound-card--a Creative X-Fi USB.
What I've found is that the M-Audio internal 192KHz card has a roughly
10dB higher noise floor (or put another way,
a 10dB poorer SNR) than the external sound sysem.
The M-Audio Audiophile 192 uses a 24-bit ADC and can sample at 192KHz.
I ended up having to turn up the gain on my pre-amplifer, in order to
compensate for the much-poorer noise performance on
the Audiophile 192.
The way things are now, I can't "see" WWVB in the spectrum. I'll see
how it is tonight, but it sure doesn't look to "be there".
This is at least consistent with my LaCrosse WWVB-synchronized
digital clock that I have, which has *never* been able to
get a lock on WWVB the entire time I've lived in this house.
I may look into the SDR-Widget system (Thanks, Patrick Strasser!), since
it boasts better performance than most other
192KHz sound systems out there, and is tailored to narrowband SDR work.
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
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