Jim,
Re the size of error
With the delta-4 card, the tx frame could be observed to be some 2 or
more seconds short of the expected time window
1 % ~ 1.2 seconds , 2 % ~ 2.4 seconds, assumedly indicating the clock on
the card runs fast, but as to the influence of the system by the
software, dma, irq etc Im not sure, one problem is I expect is the
soundcards are not designed to be the interface for a accurate frequency
meter / generator and as such compromises 'must' exist ...
The only comparison I can think of is the running of a movie at shot at
24 fps for projection , on a tele cinie system at 25 fps to sync with the
uk 50 hz frame rate , giving a lift in the sound pitch of + ~ 4 % ? , I
know that this dose generate irate phone calls from musicians pointing out
that orchestras appear to be 'sharp' but not many hi .. so its possible
a tolerance of 2 % may be accepted
G .
--------------------------------------------------
From: "James Moritz" <[email protected]>
Sent: Saturday, September 12, 2009 1:33 PM
To: <[email protected]>
Subject: LF: Re: WOLF/WSPR Sound card issues
Dear Dave,
AC 97
(http://download.intel.com/support/motherboards/desktop/sb/ac97_r23.pdf )
specifies 48kHz as the basic, obligatory sample rate for compliant sound
cards, so yours should certainly be able to do it - to find more info, you
could try looking for the audio codec chip on the motherboard - usually a
very tiny square 48pin thing near the audio connectors, and searching
using
its type number. But I guess what sample rate is actually used will depend
on software, drivers and so forth - perhaps someone with experience of PC
sound card programming could advise. Looking at the audio settings in the
Windows control panel may well tell you what sample rates are possible.
Also, some software allows you to select different sample rates, for
instance Spectrum Lab, but not Argo as far as I know.
The errors you are getting in the measured frequency seem to be enormous -
2
or 3%, which would certainly give rise to problems.
Cheers, Jim Moritz
73 de M0BMU
----- Original Message -----
From: "Dave Sergeant" <[email protected]>
To: <[email protected]>
Sent: Saturday, September 12, 2009 11:59 AM
Subject: LF: WOLF/WSPR Sound card issues
It seems that both WOLF and WSPR are
designed for current sound cards which have 48,000 and 96,000 clock
rates. Mine is obviously from the old stable so has 44,100 etc rates.
For information it is the sound card interface built into the
motherboard, an ASR Rock K7S41GX dating from 2003 with generic AC'97
sound. Zilch more given about its spec in the manual.
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