Question - "no-communication squelch" / PR Frequency?

[marcspaz]

 

I am totally bewildered by a radio feature and can't find an answer anywhere.  I found one single page that says it reduces background noise when there is no audio is present, but that absolutely isn't happening on any of my radios.  Hopefully some of the smart people here know what this stuff is.

 

I have several Yaesu radios that have a squelch type called "PR" in the radio menu, and "No-Communication Squelch" in the manual.  There is nothing in any of the manuals I have that explain what No-Communication Squelch / PR is.  The only thing in any of the manuals is how to turn it on and how to set the "PR Frequency".  That's it.

 

Normally, I wouldn't even care, as long as the squelch works.  However, no matter what I do, it doesn't seem to squelch anything.  Like nothing.  It doesn't act as a regular squelch, a reverse squelch, really has no impact whatsoever on how the radio seems to work.  It exacts like nothing has been enabled.

 

Does anyone know what the heck PR / No-Communication Squelch is and actually does?

 

[SteveShannon]

7 hours ago, marcspaz said:

 

I am totally bewildered by a radio feature and can't find an answer anywhere.  I found one single page that says it reduces background noise when there is no tone present, but that absolutely isn't happening on any of my radios.  Hopefully some of the smart people here know what this stuff is.

 

I have several Yaesu radios that have a squelch type called "PR" in the radio menu, and "No-Communication Squelch" in the manual.  There is nothing in any of the manuals I have that explain what No-Communication Squelch / PR is.  The only thing in any of the manuals is how to turn it on and how to set the "PR Frequency".  That's it.

 

Normally, I wouldn't even care, as long as the squelch works.  However, no matter what I do, it does seem to squelch anything.  Like nothing.  It doesn't act as a regular squelch, a reverse squelch, really has no impact whatsoever on how the radio seems to work.  It exacts like nothing has been enabled.

 

Does anyone know what the heck PR / No-Communication Squelch is and actually does?

 

I can’t claim to “know” what it is, but this tidbit from the FT5DR Advance manual seems to describe it:

User Programmed Reverse CTCSS Decoder
The tone signal frequency can be set at 100 Hz intervals between 300 Hz and 3000 Hz to mute the audio when receiving a signal containing a CTCSS tone matching the programmed tone.

1. Press the [F MENU] key[SQTYP].
2. Rotate the DIAL knob to select “PR FREQ”.
3. Press the PTT switch to save the setting and return to
normal operation.
4. Press the [F MENU] key[CODE].
The setting screen containing the CTCSS tone
frequencies is displayed.
5. Rotate the DIAL knob to select the desired CTCSS
tone frequency.
300Hz to 3000Hz (100Hz steps)
6. Press the PTT switch to save the setting and return to
normal operation.

So, a person could assign different PR Frequencies to different radios and then selectively block the audio when receiving a signal from a radio that sends the same PR Frequency.  Maybe for blocking audio from APRS  or digital transmissions on an analog radio?  1600 Hz is the default.

[marcspaz]

@Sshannon I tried that method too. No luck. It doesn't mute or unmute when the tone is present. Mine defaulted to 300, but i tried several times and none of the selected tones worked. 

[SteveShannon]

1 hour ago, marcspaz said:

@Sshannon I tried that method too. No luck. It doesn't mute or unmute when the tone is present. Mine defaulted to 300, but i tried several times and none of the selected tones worked. 

Then, I don’t know.  Might have to ask John Kruk.

[marcspaz]

 

Well, I was fortunate enough to have someone able to answer the question for me.

Huge Thank You to Shitao "Ken" Zhou for helping me (and others, I'm sure) understand what this function is for.  This is why I love the radio community.

Link to original post from Ken...

 

Content from his thread...

Hi, BA7NFW here.

Background infomation

When I searched for "No-communication squelch" function, which you can find on most yaesu radios, I came across this post ('cause it shows up on google).

Basically we can't make this function work, not even have an idea why this function exists when TONE Reversed mode already works fine.

I had the same confusion, and the question wasl unresolved. (btw, can someone post under that question just to tell Marc I have an answer now? I'm not living in FCC regulated territory and don't have a GMRS call sign, hence not able to register here)

tl;dr  PR Frequency function is used for the Japanese railway radio repeaters.

From the FT5DR/FT5DE Advance Manual, PR FREQ is a frequency of 300-3000Hz used for Reverse CTCSS Decoder:

User Programmed Reverse CTCSS Decoder The tone signal frequency can be set at 100 Hz intervals between 300 Hz and 3000 Hz to mute the audio when receiving a signal containing a CTCSS tone matching the programmed tone.

So it's natural to think, PR FREQ = user Programmed Reverse ctcss decoder FREQuency.

And that's the tricky part. Took me about half-day researching until I checked the Japanese version of the manual.

So, PR here actually means Private Railway(私鉄).

The Japanese Railway (JR) and other railway companies (PR) use a system of radio repeaters. When the repeater is standby and no one is using it, it keeps sending a monotone of 2280Hz (for JR, PR may use other tone between 300-3000Hz) to represent that status. If not specially handled, this may keeps your squelch opened.

And that makes sense, this function will cancel a certain tone carried in FM mode, and it's not a standard CTCSS tone signal, therefore a separate function was implemented.

I highly suspect if this function is actually useful outside Japan. And the terrible translated manual just makes everything more confusing.

That's all.

Ken (BA7NFW)