If I remember correctly, The reason for the reverse phasing came to be , was to stop the old reeds that used to be used in the CTCSS decoders, imediately to force the decoders to squelch the receiver before the squelch noise. (sometimes called squelch crash). I'm not sure that I understand the meaning of the term "HI-Q solid state detectors" unless refers to the L C type of tone detectors that were used origonally to decode DTMF. Now tones are detected by Phase detectors, some form of FFT in software, or Active filters using OpAmps. The phase reversal can acheve the same or similar results in these. 73 Coy
--- In [email protected], "Fred Seamans" <[EMAIL PROTECTED]> wrote: > To Jim & et all: > Actually there is a reason that Motorola and GE (now M/A-COM ) used a > reverse CTCSS tone burst. The Hi-Q solid state tone detectors that are used > by these manufactures have a ring down time delay, the same as trying to > stop a mechanical reed after removal of the driving tone. The design of the > solid state detector dictates the amount of phase shift of the CTCSS tone > that is ideal to stop the ring down of the Hi-Q networks. Both Motorola and > GE used the amount of phase delay that worked best with their design. It was > not to make other brands function poorly. > Fred > W5VAY > ----- Original Message ----- > From: "Jim B." <[EMAIL PROTECTED]> > To: <[email protected]> > Sent: Friday, October 29, 2004 1:45 PM > Subject: Re: [Repeater-Builder] TKR-740 versus TKR-750 (Was: Maggiore's > Service) > > > > > > Eric Lemmon wrote: > > > > > Unfortunately, the TKR-740 receiver cannot properly respond to > > > a Motorola reverse burst, but that is a deficiency that I can live > > > with. (Geez, I wish Ham radios could encode and decode reverse burst!) > > > > > > > That's actually Motorola's fault. I think they and M/A-Com are the only > > ones who use other than a 180 phase shift for revese burst, and they do > > it deliberately to make other brands not sound as good on their systems. > > -- > > Jim Barbour > > WD8CHL > > > > > > > > > > > > > > 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/
