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By turning of CTCSS/DCS can there be an increase in performance*?

*Performance:

  • Battery life
  • Latency
  • Range
  • Voice quality

From what I understand CTCSS/DCS is extra work for the IC inside the radio. Of course it is going to be minuscule, but will there be any savings/improvements from an engineering point of view? Before I do actual testing I'd like to know if anybody has been down this path?

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  • $\begingroup$ I don't think I've ever seen equipment docs that mention (for example) battery life for standard operation with CTCSS/DCS on or off, so it must be marginal when compared with frequency and operating mode, $\endgroup$
    – user21417
    Jan 18, 2022 at 22:00
  • $\begingroup$ You are right, I've yet to find manuals talking about this. Maybe because if they did the manuals would become equivalent to a 300 page book on ham theory. Just my 2 cents. $\endgroup$
    – user160357
    Jan 22, 2022 at 19:51
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    $\begingroup$ I mean good manuals have a single page that tells you some specifications on expected battery life in many modes of operation. None of them I've seen talk about standby or notification modes where CTCSS or DCS is on or off. It's assumed you'll have one or the other enabled for standby repeater operation. Monitoring for a tone is just a different sort of squelch if you look at it the right way. "Wake up and sample" is what low-power microprocessors excel at, and they are doing it anyway. Looking for a tone isn't much more work that what it is doing anyway. $\endgroup$
    – user21417
    Jan 23, 2022 at 1:19

1 Answer 1

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Battery life

Very unlikely.

Latency

Also unlikely, because most tone decoders don't operate in a way that adds latency to begin with, they're purely "backwards-looking". They take a few milliseconds to open the squelch when a new transmission starts, but they don't add any lag to the path between the demodulator and the speaker.

Range

Sort of, slightly, maybe. If the signal is weak enough that the tone (or digital code) isn't reliably copied, then the squelch won't open and you won't hear anything. If you turn off the decoder, then your brain might be able to do a better job of interpreting noisy speech than the tone decoder does of decoding noisy tone.

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  • $\begingroup$ Yes, my preliminary testing conforms with your answer. Battery life: no effect. Latency: few ms delay when opening. Range: reception is patchy compared to the one with no encoding (only when range is pushed to the limits, otherwise none). But when testing something very interesting was observed - voice quality. Unencoded transmission was noticeably richer as opposed to CTC/DCS. Further testing is needed to confirm this (I'll share my findings soon). Till then I'm editing the question to include voice quality as a factor. Thank you for your input hobbs. $\endgroup$
    – user160357
    Jan 22, 2022 at 19:24
  • $\begingroup$ @user160357 that's believable although probably radio-dependent. Most receivers filter out the frequencies below about 300Hz where tone and DCS live, so they don't get to the speakers. Some don't bother at all. Some might switch the filter in and out depending on whether the decoder is enabled, but I haven't heard of that myself. $\endgroup$ Jan 22, 2022 at 19:43

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