Dave, > My sound card calibrates to 48009.37, which is .9998% fast So the offset is +0.0195 %
> I transmit with an audio frequency of 2415 Hz > I am therefore actually transmitting on 2439 Hz, or .9998% higher No in TX it will be the reverse of RX. The true TX frequency will be equal to : 2415*(1+0.0195/100)=2145.47 Hz Reversely, if you listen to a a 2145.47 Hz transmission, it will be appear for your program as a 2415 Hz transmission. 73 Patrick ----- Original Message ----- From: "Dave 'Doc' Corio" <[EMAIL PROTECTED]> To: <digitalradio@yahoogroups.com> Sent: Tuesday, October 07, 2008 11:28 PM Subject: Re: [digitalradio] Re: Sound card question > Thanks, Patrick! > > If I understand this, then, here is what I should expect: > > My sound card calibrates to 48009.37, which is .9998% fast > I transmit with an audio frequency of 2415 Hz > I am therefore actually transmitting on 2439 Hz, or .9998% higher > than indicated > > Does that sound right? > > Tnx es 73 > Dave KB3MOW > > > Patrick Lindecker wrote: >> >> Hello Dave, >> >> It is simple. If the offset in sampling frequency is x% and the true AF >> frequency is f0, the displayed frequency f will be equal to >> f=f0*(1-x/100) >> Example: if the sampling offset is +1% and f0 is 1000 Hz, the frequency >> displayed will be equal to 1000*(1-0.01)=990 Hz >> >> 73 >> Patrick >> >> ----- Original Message ----- >> From: "Dave" <[EMAIL PROTECTED] <mailto:dcorio%40zitomedia.net>> >> To: <digitalradio@yahoogroups.com >> <mailto:digitalradio%40yahoogroups.com>> >> Sent: Tuesday, October 07, 2008 3:57 PM >> Subject: [digitalradio] Re: Sound card question >> >> > Thanks, Simon! It makes sense that if the "native" speed is 48K, any >> > other speed would require some type of "conversion". >> > >> > One more question, if I can impose on your good nature! >> > >> > What impact, if any, does the error in sampling rate have on any >> > TX/RX offset? During the Tara Rumble I noticed that almost every >> > station that responded to my CQ, came back a bit lower in frequency >> > than mine. One station I responded to even told me I was off- >> > frequency. I don't believe my IC-746 has any offset, and my RIT/XIT >> > was off. Does that large error rate of 6984 ppm create an offset, and >> > can I determine how great it is? >> > >> > Tnx es 73 >> > Dave KB3MOW >> > >> > >> > --- In digitalradio@yahoogroups.com >> <mailto:digitalradio%40yahoogroups.com>, "Simon Brown \(KNS\)" >> > <[EMAIL PROTECTED]> wrote: >> >> >> >> It means that the drivers are better - the internal clock runs at >> > 48kHz, >> >> other rates are created by either the driver or (very often) >> > Windows. >> >> Windows XP does not do a good job of this, VISTA however is >> > excellent at >> >> converting the sample rates. >> >> >> >> Simon Brown, HB9DRV >> >> www.ham-radio-deluxe.com >> >> >> >> ----- Original Message ----- >> >> From: "Dave 'Doc' Corio" <[EMAIL PROTECTED]> >> >> > I've calibrated my sound card (Diamond PCI) two ways, using >> > MMSSTV >> >> > at 48000 Hz, and MMTTY at 11025 Hz. Here are the results of the >> >> > calibration: >> >> > >> >> > MMSSTV 195 PPM 48009.37 >> >> > >> >> > MMTTY 6984 PPM 11102 >> >> > >> >> >> > >> > >> > >> > ------------------------------------ >> > >> > Announce your digital presence via our Interactive Sked Page at >> > http://www.obriensweb.com/sked <http://www.obriensweb.com/sked> >> > >> > 30M digital activity at http://www.projectsandparts.com/30m >> <http://www.projectsandparts.com/30m> >> > >> > Recommended software : DM780, Multipsk, FLDIGI, Winwarbler ,MMVARI. >> > Yahoo! Groups Links >> > >> > >> > >> > >> > >> >> > > ------------------------------------ > > Announce your digital presence via our Interactive Sked Page at > http://www.obriensweb.com/sked > > 30M digital activity at http://www.projectsandparts.com/30m > > Recommended software : DM780, Multipsk, FLDIGI, Winwarbler ,MMVARI. > Yahoo! Groups Links > > > > >
