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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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7th Apr 2020, 12:10 am | #21 |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,587
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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.
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15th Aug 2020, 1:52 pm | #22 |
Pentode
Join Date: Oct 2018
Location: Carrickfergus, County Antrim, Northern Ireland, UK.
Posts: 126
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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 |
Heptode
Join Date: Jan 2008
Location: Ashhurst, Manawatu, New Zealand
Posts: 571
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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.
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Cheers - Martin ZL2MC |
11th Dec 2020, 10:10 pm | #24 | |
Rest in Peace
Join Date: Mar 2011
Location: Basildon, Essex, UK.
Posts: 4,100
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Re: CTCSS frequencies - why the odd numbers?
Quote:
I bet you haven't seen a screen like that for a while. Mike |
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