[Lowfer] Ultra accurate soundcard calibration

[jrusgrove at comcast.net]

Todd

Guess it's all a matter of accuracy.

I've found it impossible to get Argo long term accuracy any better than ± .01 Hz. It seems as 
through one runs into 'rounding errors' or something similar preventing it from remaining spot on 
... if it can even be made to be spot on in the first place. The best I could guarantee a frequency 
readout using WWV 500 or 600 Hz tones to cal Argo would be ± .02 Hz.

While ± .02 Hz is more than accurate enough for an Argo display considering it's internal ± .01 Hz 
limitation, the same is not true of WOLF which can measure to .001 Hz. WOLF can not be cal'ed 
directly using the WWV 500 or 600 Hz tones because the WWV signal doesn't provide the level of 
stability required. If one takes the cal information from Argo and manually modifies the WOLF 
sampling rate accordingly the best one could hope for would be a similar accuracy as that of Argo ± 
.02 Hz. The Ultra Accurate Soundcard Calibration setup can cal WOLF to better than .001 Hz. Whether 
this level of accuracy is important is open to debate. All I've done is show a way of doing so 
without highfalutin test equipment.

Jay W1VD  WD2XNS  WE2XGR/2


----- Original Message ----- 
From: <ToddRoberts2001 at aol.com>
To: <lowfer at mailman.qth.net>
Sent: Sunday, March 03, 2013 12:23 PM
Subject: Re: [Lowfer] Ultra accurate soundcard calibration


> In a message dated 3/3/2013 11:40:51 A.M. Eastern Standard Time,
> jrusgrove at comcast.net writes:
>
> Ultra accurate sound card calibration using a 'spare' computer and Spectrum
> Laboratory.
>
> http://www.w1vd.com/SoundcardCalibration.html .
>
> Jay  W1VD  WD2XNS  WE2XGR/2
>
>
> Thanks for the info, Jay. So far I have had pretty good luck using
> John W1TAG's suggestion to tune in WWV in the AM mode and
> use the 500 or 600Hz tones for a super-accurate audio frequency.
>
> Then I check the sound card calibration using ARGO to see what it  reports
> the audio tone as. In my case ARGO says the tone is within .01Hz of  500Hz.
> so I figure the calibration should be close enough?  If someone  is already
> familiar with ARGO wouldn't that work as well as Spectran for this
> purpose?
>
> 73 - Todd WD4NGG
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