Guys, this is nothing more than really low-frequency DTMF. It should work fine if the levels are low enough that they're not clipped or otherwise distorted. In a non-linear stage, they'll cause audio intermodulation distortion.
If the combined voice + CTCSS level hits the limits of a clipper for a long enough duration, (like the guys who feel the need to key their mics before thinking of what they'll say, and fill with "uhhhhhhhh...") you could drop the receiver if the audio distortion confuses the CTCSS decoder. But that could happen with a single tione, too. 73, Paul, AE4KR ----- Original Message ----- From: Ron Wright To: [email protected] Sent: Sunday, July 20, 2008 1:10 PM Subject: Re: Re: RE: [Repeater-Builder] Re: PL Problem John, I've wondered about multi-PL tones at one time. I am sure with the older reeds not a problem, but newer IC type usually take in the PL, strip off the higher freq audio leaving only the PL and then feed to a pin that I am sure is counting the period or doing some period averaging. The Comm Spec TS64 has to be this way for they use a 6800 ventage CPU for their decoder. If 2 PLs were present this would have a wierd wave form and bet might not decode. I've never tried it, but would be interesting to try. I have used multi-PLs on a single rcvr for control and other purposes, but never at the same time. 73, ron, n9ee/r >From: JOHN MACKEY <[EMAIL PROTECTED]> >Date: 2008/07/20 Sun PM 02:58:29 EDT >To: [email protected] >Subject: Re: RE: [Repeater-Builder] Re: PL Problem > >You are correct, a good rig will have a PL filter so you don't hear it. But >many of these newer Yae-com-wood radios don't seem to have adequate >filtering. > >So I try to run my repeater PL tone at about 450 Hz, which has worked well. > >I know that 15 years ago I set up a GE Mastr Pro repeater with dual PL >encoding on the transmitter for a special project. I put each (comm-spec) PL >encoder at 350 Hz deviation and every decoder was able to lock up. Two PL >tones deviating at 350Hz each gave me about 750 Hz PL deviation on the >repeater transmitter. I had to build a filter network to roll off the sum of >the PL tones; 100 Hz and 146.2 Hz wanted to produce a third PL tone. So I >built a filter network which started to roll off every thing above 200 Hz >before it went in to the modulator stage. > >I do remember testing with various decoders and found that going below 300 Hz >PL deviation made decoding unreliable. > >------ Original Message ------ >Received: Sun, 20 Jul 2008 11:47:12 AM PDT >From: Ron Wright <[EMAIL PROTECTED]> >To: [email protected] >Subject: Re: RE: [Repeater-Builder] Re: PL Problem > >> A good rig has a PL filter so you don't hear it, but know it comes thru on >some rigs. Does sound annoying when it does. >> >> Also need to remove from the repeater receiver for it might beat with the tx >generated PL due to it being slightly different freq/phase. Most rigs will >not pass low freq PL thru their audio input. This is why most rigs have >seperate input for PL encode. >> >> 73, ron, n9ee/r >> >> >> >> >From: JOHN MACKEY <[EMAIL PROTECTED]> >> >Date: 2008/07/20 Sun PM 02:37:13 EDT >> >To: [email protected] >> >Subject: RE: [Repeater-Builder] Re: PL Problem >> >> > >> >I set all my repeaters for 450 Hz to 550 hz and have never had a problem >with >> >listeners being able to decode. >> > >> >so something in the range that David suggests below should be fine. >> > >> >I know some people who think PL level should be set at 750 hz to 900 hz. >In >> >my opinion, that is way to high, and it is annoying to hear the PL tone >which >> >can be done at those levels. >> > >> >------ Original Message ------ >> >Received: Sun, 20 Jul 2008 06:45:05 AM PDT >> >From: "David Murman" <[EMAIL PROTECTED]> >> >To: <[email protected]> >> >Subject: RE: [Repeater-Builder] Re: PL Problem >> > >> >> Run all my repeaters with a tone of 600 hz. This is what GE recommended >> >when >> >> I was in the 2-way business. So far all three repeaters, two VHF and >one >> >> UHF have had no problem with any radio being able to decode the tone. >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> David >> >> >> >> >> >> >> >> -----Original Message----- >> >> From: [email protected] >> >> [mailto:[EMAIL PROTECTED] On Behalf Of nj902 >> >> Sent: Saturday, July 19, 2008 9:37 PM >> >> To: [email protected] >> >> Subject: [Repeater-Builder] Re: PL Problem >> >> >> >> >> >> >> >> Actually, what I think what I confirmed is that I passed reading >> >> comprehension... >> >> >> >> >> >> The "Standard" is 500 to 1000 Hz . Period. >> >> >> >> ................................................................. >> >> >> >> --- In Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com> >> >> yahoogroups.com, "Eric Lemmon" <[EMAIL PROTECTED]> >> >> wrote: >> >> >> >> " My statement about the definition of "Standard CTCSS Modulation" is >> >> correct, and thank you for confirming that. ..." >> >> >> >> >> >> >> >> >> > >> > >> >> >> Ron Wright, N9EE >> 727-376-6575 >> MICRO COMPUTER CONCEPTS >> Owner 146.64 repeater Tampa Bay, FL >> No tone, all are welcome. >> >> >> > > Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
