9

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 gets to your ears, and will also prevent an errant tone near the microphone from triggering a repeater somewhere. Some of us might not agree that the tones are ...


8

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 and the demodulated signal will be heavily distorted. PL tone, which is part of the transmitted signal, will also be lost. If one of the RF signals gets to the ...


8

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 passing only the expected tone, or a frequency counter which determines the frequency of the tone in the signal which is then compared with the expected tone ...


8

"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 whether it has a tone.) The transmitted tone is necessary to "open up" most repeaters so that you can talk on them. "CTCSS", displayed as "CT" on the main screen, ...


8

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. https://en.wikipedia.org/wiki/Continuous_Tone-Coded_Squelch_System Also, the CTSS tone is injected at a lower level than the voice content, usually 15% of full ...


7

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). Using a constant ratio rather than a constant difference avoids two different tones being exact multiples of each other. If you used a constant difference of 10 ...


6

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 you 83 codes, whereas CTCSS gives you somewhere between 26-50 squelch tones depending on the radio -- manufacturers have added extra codes over time. For ...


5

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 appropriate for the task at hand. Amateur radio is not suitable for the use case you are describing, and a mobile phone is.


5

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 sure to ID at the start of your transmission and every 10 minutes if it goes on longer than that. Privacy is relative, though. Someone with a scanner might catch ...


5

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 old NE567) and algorithms are designed for a single Q, and the frequency changes don't change the Q. Distortion is quite normal in electronics — low tones like ...


5

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 the whole audio range. The decoder in a CTCSS system is based on a very narrow bandpass filter which passes the desired CTCSS tone. There is a balance between a ...


4

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. With a tone squelch (and I use that term broadly here to refer to CTCSS, DCS and any other possible, similar schemes) configured for receive squelch, the ...


4

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 Amateur Radio. The BF-888S can be programmed to use frequencies in the range of 400 to 470MHz which nicely permits programming the radios for the 70cm Amateur ...


4

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 digital voice mode that includes encryption, but I can't name one that would definitely work simplex (e.g. P25 can be encrypted but is as far as I know always “...


3

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.


3

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 annoying hum when listening to NFM from local 2M repeaters. (I obviously switch that subroutine out when listening to broadcast wideband FM music.)


3

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. Usually the radio has a tone scan function, and you can use that to find out what tone is being used. You can also turn on tone squelch if you have the tone set ...


3

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 of theory about CTCSS. The name means Continuous Tone-Coded Squelch System. It's not a privacy system, it's a squelch system! It works by sending a tone-code ...


2

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 adds a low frequency tone to the baseband input to the FM modulator. Standards vary, but the amplitude of this tone is around 15% of the deviation. The amplitude ...


2

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. Make sure to set the tone value to your desired tone after entering CTCSS mode.


1

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 thing: send a tone on transmit.


1

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 call sign back. My radio is not yet supported by CHIRP, so I had to use the Alinco software to program the radio. For that channel I have encode set to D023N (...


1

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 last few days, you could have been doing everything correctly but being stomped out by stronger stations. I assume you are just starting out with satellites, ...


1

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 priced accordingly. Borrow a better HT (ideally Icom, Yaesu or Kenwood, but Alinco makes pretty good handhelds too although they're harder to find) and see if ...


1

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 HT: Use a non-open-source digital mode. Yaesu’s C4FM-based System Fusion is a good example. It is registered with the FCC, but for all intents and purposes, ...


1

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), converted it to mono WAV (it's stereo for some unclear reasons), and built this flow graph in GNU Radio companion from scratch: What is missing is a lookup ...


1

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 name suggests it is a very mathematically oriented application. Plus, it is something you have to buy yet there is a free trial period you could use to ...


1

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 CCIR However, I tried it out with a couple of sample files I found on the Internet and it didn't produce any output.


1

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 what it is and could use it without paying dues to the club. The school may be of the same mind.


1

The best way to use a Baofeng to communicate with any walkie talkie is to: Find the frequency. Make sure you are on the right frequency by transmitting from the midland walkie talkie to your Baofeng. Run a tone decoder. In the option "R-CTCS", the bafeng has a tone decoder by pressing either the # button or the * button. When the tone decoder is running, ...


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