9 votes
Accepted

Why don't I hear the CTCSS tones when listening on the repeater input frequency?

Many radio manufacturers are aware that people don't want to hear CTCSS tones - so they put high-pass filters on both the output (speaker) and input (microphone). That eliminates the tone before it ...
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  • 1,615
8 votes
Accepted

Can two FM radios transmit two separate PL tones at the same time, and be received by two radios with matching PL tones?

Assuming that the two transmitters operate at the same carrier frequency, and that the receivers receive similar power from each transmitter, then the FM signals will suffer destructive interference ...
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  • 1,099
8 votes
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Would it be possible to transmit all CTCSS tones at once?

You could get several different results, depending on exactly how the receiver recognizes the expected tone. From a small amount of web research, it sounds like the usual methods are either a filter ...
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8 votes
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Kenwood TH-D72A: what's the difference between Tone and CTCSS?

"Tone", displayed as "T" on the main screen, selects tone encoder + carrier squelch (your HT will send a tone, selected by the TONE Freq menu, and receive any strong-enough signal, regardless of ...
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  • 8,730
8 votes
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PL tone removal?

I would expect some low-frequency roll-off in the amp and the speaker. You could check by putting headphones on the speaker output. Wikipedia says that a 300 Hz cutoff high-pass filter is common. ...
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7 votes

Why are PL tones strange numbers?

The ratio between PL tones is roughly constant. From a list of PL tones, you can calculate the ratio between each frequency, which turns out to be about 1.035 (with some exceptions, not sure why). ...
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6 votes

Advantages of using Digital Code Squelch

DCS (aka DSQ/DPL) provides a slightly larger range of codes to pick from compared to CTCSS. This means less chance that a nearby station will accidentally overlap with yours. Specifically, DCS gives ...
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5 votes

Private Channel?

There is a way to use radio waves to hold a private conversation. It's called a mobile telephone, and they are available with surprisingly good coverage around the world. We should always use a tool ...
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  • 4,281
5 votes

Private Channel?

You cannot limit others from using a channel. But as long as you have a license then you can operate anywhere in the band in question, and there are a lot of underutilized frequencies. Just be ...
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  • 2,021
5 votes
Accepted

Why are PL tones strange numbers?

Greg Hewgill's answer is correct, but merits a slight explanation. Constant (percentual) relations mean that the Q-factor of the detector for the tones remains constant. Most detector chips (like the ...
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  • 699
5 votes
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How do PL tones make it through so much noise?

As Michael noted, a repeater's CTCSS system is looking for a very specific frequency with a very low deviation (typically 10% or less) as low as about 40 dB down. What you are hearing is of course ...
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  • 6,264
4 votes
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Receiving without configuring CTCSS

Your understanding of tone squelch is wrong. Tone squelch is simply an extension to the squelch system. Normally, the squelch opens whenever the received signal is stronger than the squelch threshold....
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  • 4,780
4 votes

Trouble communicating between Baofeng and Midland walkies

The BF-888S radios have a 16-channel knob on the top and no LCD display nor a number keypad. The BF-888S is marketed all over the world for use mostly in licensed commercial operation or licensed ...
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  • 317
4 votes

Private Channel?

No. It is not legal. You may not hide the content of your message when making use of amateur frequencies, no matter what means you use to do so. Technically, all you would need is radios supporting a ...
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3 votes

Does DCS intefere with SDR reception?

Short answer: No. The whole point of SDR is that the physical receiver doesn't care what the kind of signal is it's receiving as long is bandwidth-wise narrow enough and amplitude-wise not overdriving....
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3 votes

Why don't I hear the CTCSS tones when listening on the repeater input frequency?

Same with SDR software. My SDR code runs on a iPhone that's connected to "HiFi" audio transducers. So I had to add a 270 Hz high-pass biquad IIR audio filtering subroutine to get rid of ...
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  • 12.4k
3 votes

Why don't I hear the CTCSS tones when listening on the repeater input frequency?

The volume of the tones is typically low enough with respect to the voice signal that you can't hear it. Occasionally the tone generator in a radio will be poorly calibrated, and you do hear it. ...
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  • 4,188
3 votes

MURS - Set to broadcast and receive on a specific CTCSS code

Here on StackExchange we call what you asked an XY problem. You're asking how to set up CTCSS, but what you really want is to have privacy. Those are two different things. First of all, a tiny bit ...
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  • 2,715
2 votes

Would it be possible to transmit all CTCSS tones at once?

No, you can't. Based on the particular method the receiver uses to decode CTCSS, multiple tones may or may not be recognized. But that's moot, because you can't transmit all the tones anyway. CTCSS ...
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2 votes
Accepted

Programming receive tone on Kenwood V71A

The tone values for Tone mode and CTCSS mode are stored separately in the TM-V71A. If you set the value when you set up for tone and then change into CTCSS mode, you'll be back at the default 88.5. ...
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  • 1,615
2 votes

Performance gain when turning off CTCSS/DCS?

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 ...
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  • 8,730
1 vote

BF-888 radios don't work with UV-5Rs on the same frequency

You might try changing the Tone Mode from TSQL to just Tone. TSQL mode does two things: sends a tone on transmit requires a tone on receive to break your radio's squelch Tone mode only does one ...
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  • 2,842
1 vote
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alinco dr-635T receive squelch will not open in DCS mode

I too have an Alinco radio with a channel set for a Peak Radio Association repeater, which uses the same CDCSS (DCS) code. I just tried, and I was able to key up my local PRA repeater and hear its ...
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  • 8,922
1 vote

Kenwood TH-D72A and AO-91/92

This might be crazy, but you were on the TX band when you attempted to TX? You should have continued to hear the downlink of you were. Sinfulness it is the simple things. Also, if it was during the ...
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  • 19
1 vote

Why does P25 occasionally break through tone squelch on my analog HTs?

It could be a bug in the repeater controller (it's perfectly possible to transmit digital data with a PL tone), but I'd suspect the Baofengs as your problem. They're not the best radios, and they're ...
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1 vote

Private Channel?

This topic came up in a discussion on a Facebook ham page. I had my own thoughts on legally narrowing the available listeners when setting up my mobile to cross-band repeat so as to catch it with my ...
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  • 11
1 vote

Software to decode selective calling tones

So, you mean something that will give you the sequence of calling tone digits like used in ZVEI1 to ZVEI5? Yeah, those were fun 5 minutes: I got an example from the sigid wiki (specifically ZVEI1-5), ...
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1 vote

Software to decode selective calling tones

I would use the application Mathematica (by Wolfram) which has a lot of computational audio features for decoding audio streams via a given codex protocol. Mathematica is not for everyone and as the ...
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1 vote

Software to decode selective calling tones

multimon-ng, which I have used for other purposes, claims to be able to decode selective calling tones of the following protocols, among other things: ZVEI1 ZVEI2 ZVEI3 DZVEI PZVEI EEA EIA ...
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1 vote

Baofeng not finding CTCSS tone

They may not be transmitting a tone at all. I had this with my Baofeng and a local club repeater I wanted to access. They only receive the tone but do not transmit it because then others would know ...
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