Stanley Reynolds wrote: > > > ________________________________ > > From: "Lux, James P" <[EMAIL PROTECTED]> > To: Discussion of precise time and frequency measurement <time-nuts@febo.com> > Sent: Tuesday, December 2, 2008 5:15:47 PM > Subject: Re: [time-nuts] Soundcard sampling Re: Picking a good HP 10811 > > > Maybe you all missed the part where I was complaining about the $15 mixers so > my investment in sound cards must be less than that, would think that at $300 > you should be able to get a real A/D card that would allow a beat frequency > down to DC. > > Should I even try with my cheap no name cards ? > > Bruce looks like the M-audio is $179 the specs look great if almost too good, > guess I should save my pennies. > http://www.digitalconnection.com/products/audio/ap192.asp ( first site > goggle turned up, did not look further ) > > Assume the one card would be 4 channels they do say multi card support but > with an * and the clock problem would need a fix not sure I would take the > solder to it till the 1 year warranty is gone but then 4 channels would work. > > Stanley > > Stanley
You can certainly start with a cheap no name card although the noise floor will be somewhat higher (typically a 16 bit motherboard sound system is at least 10x noiser than the AP192, some have lots of spurs others are quieter). For a long enough averaging time the system noise level even with a cheap card will be somewhat lower than any OCXO you are likely to have. A cheap card will at least establish that in principle the technique works. You can then decide whether to upgrade it. The AP192 cards only have 2 input channels. Real AD cards with adequate performance are usually far more expensive than $300. In principle, one could build an ADC card with adequate performance using 4 AD7760 ADCs. Bruce _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.