CTCSS frequencies - why the odd numbers? - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

SiriusHardware · 7th Apr 2020, 12:10 am

That would be the right way to do it, or, if you are handy with microcontrollers like PICs or AVRs, one of the ones which have programmable PWM outputs, you could use one of those followed by a simple filter to generate your chosen CTCSS 'area' tone.

TALKINGWITHPYE · 15th Aug 2020, 1:52 pm

Hello all, talking of CTCSS, do any of you remember the Ferritronics community repeater panel? Fiddly things to set up but they were reasonably stable once tuned. Each tone had its own card with a multiturn pot to set the frequency. Then came the good old Zetron Panel, much easier to configure with a laptop. A clever engineer managed to develop a control panel for a council to separate its different departments, this was built into a 37 way D connector fitted onto a Philips PRF 1050 repeater. A council which I had dealings with was plagued with abuse of their system so I developed an extended program in their Zetron panel so that talk through could be switched off on a particular group, resulting in the mobiles could only talk to the office.

Dave

majoconz · 9th Dec 2020, 5:08 am

Aircraft HF comms use a similar system to wake up the pilot on those long boring over-water sectors. The voice comms are USB but the selcall tones are transmitted with full carrier so that the decoder can lock on to it. Here's the tones. They are transmitted with two tones together and then another two. Not so long ago there we only 8 tones but when there got to be much longer flights with world-wide destinations there were too many overlaps so the system went to 16 tones.

crackle · 11th Dec 2020, 10:10 pm

Quote:

Originally Posted by Biggles

When I used to work with Motorola radio gear the CTCSS tone was always referred to as a "PL" tone, as in private line. This might be worth remembering if you happen to do any searching on the web for info. The tones are the same as those used in the UK but I am not sure if our friends across the water were the first to use the system.

Oh so that is what PL stands for, I did wonder when I setup a Motorola Visar with a couple of channels to use out local Danbury Repeater..

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I bet you haven't seen a screen like that for a while.

Mike

7th Apr 2020, 12:10 am	#21
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,556	Re: CTCSS frequencies - why the odd numbers? That would be the right way to do it, or, if you are handy with microcontrollers like PICs or AVRs, one of the ones which have programmable PWM outputs, you could use one of those followed by a simple filter to generate your chosen CTCSS 'area' tone.

15th Aug 2020, 1:52 pm	#22
TALKINGWITHPYE Pentode Join Date: Oct 2018 Location: Carrickfergus, County Antrim, Northern Ireland, UK. Posts: 126	Re: CTCSS frequencies - why the odd numbers? Hello all, talking of CTCSS, do any of you remember the Ferritronics community repeater panel? Fiddly things to set up but they were reasonably stable once tuned. Each tone had its own card with a multiturn pot to set the frequency. Then came the good old Zetron Panel, much easier to configure with a laptop. A clever engineer managed to develop a control panel for a council to separate its different departments, this was built into a 37 way D connector fitted onto a Philips PRF 1050 repeater. A council which I had dealings with was plagued with abuse of their system so I developed an extended program in their Zetron panel so that talk through could be switched off on a particular group, resulting in the mobiles could only talk to the office. Dave

9th Dec 2020, 5:08 am	#23
majoconz Heptode Join Date: Jan 2008 Location: Ashhurst, Manawatu, New Zealand Posts: 570	Re: CTCSS frequencies - why the odd numbers? Aircraft HF comms use a similar system to wake up the pilot on those long boring over-water sectors. The voice comms are USB but the selcall tones are transmitted with full carrier so that the decoder can lock on to it. Here's the tones. They are transmitted with two tones together and then another two. Not so long ago there we only 8 tones but when there got to be much longer flights with world-wide destinations there were too many overlaps so the system went to 16 tones. Attached Thumbnails __________________ Cheers - Martin ZL2MC