Programming Duplex Frequencies

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Programming Duplex Frequencies

Postby Wykenwizard » Thu Sep 14, 2017 11:34 am

I have been using various scanners for many years, but have never really understood how duplex frequencies should be programmed in for best results. I am currently using a Bearcat UBC125XLT and Arc125 software. My question is, when programming duplex frequencies should they be entered together in a bank or just in numerical order of frequency? My main usage is for listening to shipping on the Humber estuary in the marine band. There are many duplex channels so how is the best way to enter them in order to pick up both sides of the conversation?
I am hoping someone out there understands what I am asking? Any advice would be greatly appreciated.
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Re: Programming Duplex Frequencies

Postby m0lsx » Thu Sep 14, 2017 12:49 pm

You program the repeater output into your scanner.
The input is for mobile radios to feed into the repeater with, it's the repeaters receiver frequency. There is then a frequency gap to avoid interference & then the repeater output frequency (transmitter.)
The repeater listens on one frequency (input) & when activated by a mobile station using the appropriate CTCSS/DCS tone, it opens the transmitter (output) & transmits what it is hearing.
The input frequency can be programmed into your scanner, but you will never hear as much as the repeater does & often nothing at all.
You can set your scanner to use the repeaters CTCSS/DCS tone & sometimes it does make sense, but leaving no DCS/CTCSS tone set, means you hear everything on that frequency. Which with many business repeaters using several tones for different users makes for more listening. Also during lift conditions you will also hear distant stations too.

Edited to add.. To be pedantic, almost all repeaters are semi duplex. That is there is not full two way comms, just one way. A telephone is duplex, as it allows a normal conversation. A amateur radio repeater is semi duplex as each users talks in turn.
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Re: Programming Duplex Frequencies

Postby m0lsx » Thu Sep 14, 2017 12:54 pm

Image
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Re: Programming Duplex Frequencies

Postby Wykenwizard » Thu Sep 14, 2017 1:38 pm

Thank you very much for your clear and concise explanation. I expect there is an idiots guide out there somewhere which is clearly what I need.
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Re: Programming Duplex Frequencies

Postby Minus1 » Thu Sep 14, 2017 2:11 pm

Very few scanner manufacturers make any attempt to properly implement duplex (or more accurately, two frequency simplex) frequencies.
I simply requires two frequencies to be stored in each memory position, with both being scanned, but the mobile one first, and then a delay where both are scanned.
I think one of the older AOR scanners had this facility but it doesn't seem to have occurred to most manufacturers. :rolleyes:
I reserve the right to ignore people who have made no attempt to the read the manual, and expect others to do it for them.
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Re: Programming Duplex Frequencies

Postby FreqFreak » Thu Sep 14, 2017 6:43 pm

Spot on, Minus1. I thought that was so obvious, so many years ago, it's painful that it never came to be. At one time I thought perhaps I could sell the idea to Uniden :biggrin:
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