Radio/Repeater Tone Question?

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ht396jm

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First Post - Sorry if its in the wrong section.

Hi, I have a question about a tone I recently heard over the Cliffside Park, NJ police channel. Their HQ consoles generate a "key-up" tone upon beginning of transmission. Their mobile and portable radios do not appear to make generate this tone upon key-up. It is generated every time the HQ console keys up. I've heard this sound in numerous NYPD transmissions as well. Does anyone know what this type of key-up noise or repeater access is called? Thanks for any help.
 

W2SJW

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NYPD uses MDC1200 on their mobiles & portables that is cut-out of the audio passband by the data-operated-squelch function in their repeaters (never on their base radios).

I find it strange that Cliffside Park would use that on their base radio & not the field units. Sometimes I will hear very short 'tweets' or 'bleeps' when NYPD base radios key-up. Is that what you are hearing?
 

kd2pm

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I dont listen to that agency but it sounds more like you are hearing the function tones that are needed to key up the repeater. When a repeater is not physically located next to the dispatcher, they will use a dedicated circuit to get to the repeater and in order to tell it to key up, a tone is used to alert it and then to have it key up and stay keyed while the dispatcher holds down the PTT key on the mic. Description is available at the link below

https://en.wikipedia.org/wiki/Tone_remote
 

RocketNJ

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If the tone you are hearing is 2175 Hz then you are most likely hearing the beginning of the high level guard tone from the console. If they are not using a comparator voting system then you would only hear it from the console since the console is connected via wireline and field units are using in cabinet repeat.
 

ht396jm

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RocketNJ and kd2pm, thank you that pretty much answered it. I had been doing research and didn't even know what to begin to type in. Additionally, if you have any idea, is there any way to purposely program this feature so that it is audible to a receiving radio when the console transmits? Our repeater is not located next to our base station, rather about 1000 feet away. Any info you could give would be helpful, thanks again.
 

RocketNJ

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It's really not a feature but rather the HLGT filters not muting the complete high level guerd tone keyup sequence.

An option would be to have your dispatch use a control station instead of direct wired connection and program the control station for MDC or other signaling at the beginning of transmission.

Two reasons why you DON't want to do this:

1. Wait for the beep. Dispatchers would have a hard time waiting that short amount of time before talking.

2. More importantly, console priority (wireline priority at the base/repeater). The console would lose the ability to have priority over field unit. Think of someone sitting on the mic :)

So, while it sounds "cool" it is really a shortcoming with the hardware or programming of their system. Trying to have some kind of sound at the beginning of console transmit is more of a problem than enhancement.
 

ht396jm

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Thanks for the help, we were exploring the option as means of hopefully limiting the amount of time it takes for the console to open the repeater. Our mobiles and portables have pre and post MDC so they hit the repeater faster than the console, it would seam. There about a 1-2 second delay from key-up until the console opens the repeater. Again, thanks for the info.
 

902

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I spec'ed the systems for both PD and FD. Guess I should cruise the boards more often.

What you're hearing is called "tone remote" keying. It's a command signal from the console to activate the transmitter. That format is not unique to CPPD or NYPD, it's used around the world. As time goes on, this sound will slowly go away as technology is replaced by digital modulation and control schemes. This was state-of-the-art in 1993 when the idea of replacing 155.610 and 154.445 (both simplex and heavily used) was being discussed.

The reason you hear it is exactly what RocketNJ said (Yo!).

As for console priority, that is a dual-edged sword. It's necessary if the repeater is locked up by the comparator (usually a stuck mic, long-winded transmission, or someone intentionally keying), the console priority would very briefly (you wouldn't notice it) drop the system and reset the time-out-timer on the repeater. The problem is that sometimes field traffic is much more important than dispatch traffic (i.e., a "MAYDAY!" call or an order to "EVACUATE THE BUILDING!"). NYPD has a unique configuration where the dispatcher receives in full duplex and never stops hearing units, even though the repeated audio might drop. The way the system you're listening to was set up was more of a stock configuration with the console priority card installed.

The original unit configurations with the Spectra mobiles and MT2000/HT1000 portables was a status/message terminal with modem output for CAD interface (apparently never got used), and mobiles with beginning of transmission MDC-1200 unit ID, portables with end of transmission ID. It seems that over the last 20+ years, someone programmed both beginning and end IDs into some radios.

At the end of the day, short radio time-out timers, and both dispatch and units saying what they mean and then letting go of the PTT button go a long way.
 

ht396jm

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Thank you for all the great answers. Sorry to keep harping on this, I've been doing research on tone remotes. If I understand the set up correctly.... a console radio would have to be physically connected to the tone remote which in turn would access the repeater via a phone line connection up key up? And the function tones could be programmed via the tone remote?
 

jim202

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I spec'ed the systems for both PD and FD. Guess I should cruise the boards more often.

What you're hearing is called "tone remote" keying. It's a command signal from the console to activate the transmitter. That format is not unique to CPPD or NYPD, it's used around the world. As time goes on, this sound will slowly go away as technology is replaced by digital modulation and control schemes. This was state-of-the-art in 1993 when the idea of replacing 155.610 and 154.445 (both simplex and heavily used) was being discussed.

The reason you hear it is exactly what RocketNJ said (Yo!).

As for console priority, that is a dual-edged sword. It's necessary if the repeater is locked up by the comparator (usually a stuck mic, long-winded transmission, or someone intentionally keying), the console priority would very briefly (you wouldn't notice it) drop the system and reset the time-out-timer on the repeater. The problem is that sometimes field traffic is much more important than dispatch traffic (i.e., a "MAYDAY!" call or an order to "EVACUATE THE BUILDING!"). NYPD has a unique configuration where the dispatcher receives in full duplex and never stops hearing units, even though the repeated audio might drop. The way the system you're listening to was set up was more of a stock configuration with the console priority card installed.

The original unit configurations with the Spectra mobiles and MT2000/HT1000 portables was a status/message terminal with modem output for CAD interface (apparently never got used), and mobiles with beginning of transmission MDC-1200 unit ID, portables with end of transmission ID. It seems that over the last 20+ years, someone programmed both beginning and end IDs into some radios.

At the end of the day, short radio time-out timers, and both dispatch and units saying what they mean and then letting go of the PTT button go a long way.
If you specked the system, why didn't the remote radios have the 2175 Hz. notch filters installed and working? This takes out the high level guard tone. Depending on the radio, you may or may not hear the function tone, depending on how long it takes the radio to key up and start producing RF. Without the filter, you can probably hear both the HLGT wakeup and the function tone come out the radio.
 

UnHumanReactions

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If the tone you are hearing is 2175 Hz then you are most likely hearing the beginning of the high level guard tone from the console. If they are not using a comparator voting system then you would only hear it from the console since the console is connected via wireline and field units are using in cabinet repeat.
Is this the kind of 2175 Hz tone you were talking about at the beginning of transmissions?

https://clyp.it/z24aajda

(Audio from my local police department)
 

UnHumanReactions

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Yes thats it, there is also a second tone after that on the sequence I'm referring to
Oh, the two tone beep. I believe that's when someone start's transmitting when the hang timer is about to close the squelch, part of the 2175 Hz tone comes through. I think. I could be wrong on that.
 

APX8000

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The two tone at the end is the tone remote command signal from the console to activate the transmitter.

Sent from my iPhone using Tapatalk
 
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jim202

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As I said back a ways, the repeater / base station is missing the 2175 Hz. notch filter to remove those tones your hearing.

If the station was modified to be remote control, then the tone adapter that was used either was strapped to not use the 2175 notch filter or it does not have one built into it.

Sounds like the radio shop that did the install didn't do their job correctly. Put it on their shoulders to correct the problem.
 
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