I agree. DTMF is two sinusoids. You don't want the limiting action to distort the signal. BTW this is also why you should use 3KHz as a baseline on linked systems to keep the audio as linear as possible through chain-linked RF repeaters.
One thing that bugs me though is that the 2005 ARRL handbook says 5KHz RMS deviation (appx 7.07 KHz) for NBFM. I beleive this is wrong. I've always used peak-to-peak/2 setting on the HP8920 service monitor. Carson's rule states that channel bandwith is 2 times the sum of the peak deviation and highest modulating frequency. If you use 5 KHz RMS deviation with a 1KHz sinusoid, the channel bandwidth will be 2*((1.414*5000)+3000) = 20.14KHz! This ain't 16K0F3E. Steve WA6ZFT > > From: mch <[EMAIL PROTECTED]> > Date: 2005/12/02 Fri PM 02:43:24 PST > To: [email protected] > Subject: Re: [Repeater-Builder] Deviation > > TT should be between 3 and 4 kHz deviation. (preferably closer to 3) > > Joe M. > > Charles Greene wrote: > > > > Ken, > > > > Shouldn't the touch tone pad tone be set at the maximum deviation or > > nearly so? Those are steady and not subject to peaks. Also I take > > it the max deviation should be set with a 1Khz audio tone applied> > > > > 73, Chas W1CG > > > > At 05:05 PM 12/2/2005, you wrote: > > >One thing that hasn't been mentioned so far, and one thing that is quite > > >important, is that regardless of the suggestion of 5 or 4.75 Khz, it must > > >be noted that these are PEAK values, not average. > > > > > >If the average deviation is set for 5 KHz, then the peaks will be > > >absolutely be more than 5 Khz. > > > > > >So use the scope in the service monitor, not the meter > > > > > >Ken > > >------------------------------------------------------------------------------ > > >President and CTO - Arcom Communications > > >Makers of state-of-the-art repeater controllers and accessories. > > >http://www.ah6le.net/arcom/index.html > > >We offer complete Kenwood TKR repeater packages! > > >We are now an authorized Telewave Dealer! > > >AH6LE/R - IRLP Node 3000 > > >http://www.irlp.net > > > > > > > > > > > > > > > > > >Yahoo! Groups Links > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
