Manchester Trunked Radio System ProVoice

[Lynch_Christopher]

Does Manchester use ProVoice at all?

[LPD7]

No real way to tell, we cant monitor Pro-Voice

[fog]

I've never had the scanner stop on something that didn't come through, though... Nor have I noticed agencies like the police (who would probably be the ones wanting to use ProVoice) with conspicuously absent transmissions. I've actually only been monitoring Manchester for a week or two, but I'd upgrade LPD7's comment to, "There's no evidence to suggest they are."

I'm curious if it's planned at all, though, as the RadioReference listing mentions. That's several years out of date, so I wonder if it's been scrapped or just delayed.

[Lynch_Christopher]

Yeah I saw it in the radio reference database that's why i mentioned it. I have a feeling that they don't use the Provoice since i hear most of their communications on the regular trunked system. But then again i agree that even if they were using we probably wouldn't know since no scanners can pick it up.,

[scancapecod]

Even the page at my Wiki is a little old, but maybe this will shed a little light.

http://www.scannewengland.net/wiki/i...H_Trunk_System

I don't recall any Provoice discussion at my site regarding this system but it may be worth a search there.

[fog]

Originally Posted by scancapecod

Even the page at my Wiki is a little old, but maybe this will shed a little light.

All I see that's relevant is, "System- Analog with Pro-Voice Digital Interface," which is just as ambiguous as on the RadioReference site.

...even if they were using we probably wouldn't know since no scanners can pick it up.

Is the data sent out over the control channel any different depending on the format, though? I'd think that the radio would still tune to the appropriate frequency when it saw that a talkgroup was active, and then the ProVoice 'noise' would come out your speaker, much like monitoring P25 on an analog scanner. Unless the control channel indicates whether a transmission is analog or not.

[scancapecod]

Originally Posted by fog

All I see that's relevant is, "System- Analog with Pro-Voice Digital Interface," which is just as ambiguous as on the RadioReference site.

Actually, that tells me that the system has the capability of using Pro-Voice. Not to mention, if they do, you won't be able to monitor it anyway. If information doesn't get updated at this site or at my site, maybe there's simply nothing to update.

How about using UniTrunker to see if any ProVoice talkgroups appear. If you've got a radio that has a discriminator tap that would be the best way to figure it out. If it shows a talkgroup labeled "Dig", there's your answer.

I'm guessing they are not (yet) using Provoice, as it's likely it would have been reported by now. There is a strong scanner community in NH that's really on top of things.

[NYRHKY94]

I believe Scott's analysis is correct. I've got a 24x7 feed running for Manchester Police & Fire and don't recall having any issues with missed communications etc.

CHRIS: As Scott mentioned, we do have a very knowlegeable scanner group in NH (lots of true radio guys). I would suggest joining the NH Scanner Yahoo Group and posting your questions there in addition to the RR site.

http://groups.yahoo.com/group/NewHampshireScanner/

[scan-manchester]

From what I have observed, every time Manchester PD mentions "Coded" (as in: "...stand-by for a coded broadcast..." or "...try it again, you were coded..."), they are referring to ProVoice. Every scanner that I have used on the Manchester TRS won't acknowledge the ProVoice transmissions. However, if you manually step through the voice frequencies when there is a coded broadcast, you will hear the raw digital stream (without the ...beep, beep, beep, beep, beep at the end like analog).

During the Ofc. Briggs funeral, Manchester had 155.475 tied into the TRS. One of the captains told another unit to go coded. When they did, you couldn't hear them on the TRS. However, it was still patched through to 155.475 (I doubt they realized it though!).

They don't use it very often, as ProVoice coverage in the city is horrible.

[fog]

Today I heard them "go coded." The scanner doesn't stop, indicating that the system indicates it differently... But I stepped through the channels and heard digital traffic that definitely wasn't an EDACS control channel.

So scanmanchester was right: it's there, just used very rarely.

BTW, ProVoice isn't actually encrypted, is it? If I were to buy a radio that did ProVoice, wouldn't they be audible? (Of course, buying used radios and putting them on a system you don't have permission to be on is a horrible idea... I'm just saying, they seem to use ProVoice as encryption, whereas I don't think it's actually encrypted.)

[scan-manchester]

This is what I've been able to find...

"...EDACS ProVoice digital now supports
DES encryption with FIPS-140 certi-
fication by the National Institute of
Standards and Technology...."
(From M/A-Com's EDACS Brochure http://www.macom-wireless.com/products/pve/default.asp
(Click on Brochure in the top paragraph - PDF File)

Also see: http://en.wikipedia.org/wiki/EDACS_Provoice

These tell me that ProVoice, itself, is actually in-the-clear digital... but is not decodable by any of the scanners on the market, thus making it pseudo-encrypted.

[jmarcel66]

Yes Manchester uses encryption. I believe it was originally called "Aegis" or something like that. It pre-dated Pro-Voice. I think they are now on Pro-Voice and "Go Coded" means use the encryption. It is typically tied to the talkgroup they are on as opposed to separate talkgroups.

The term dates back to their High-Band days (156.210 Ch-1, 154.845 Ch-3) when they used DVP/DES encryption similar to what the fed's used to use before P25 encryption.