EDACS Provoice

[Thayne]

I assume that any EDACS capable scanner would still follow Provoice talkgroups, even if you couldn't hear any audio. Does anyone know if this is true?

If so, then if you feed a Discriminator tap into a proper DSP or DA converter you should theoretically hear the audio??

Any thoughts on this??

 

[Dog]

From what i understand there is no way to "track" a Pro Voice signal. The data channel uses a the Pro Voice standard. And also from what i understand you can here the voice channels as long as they are not encrypted(sp?) but you can't track the talk group.

I may be wrong but that is how i understand it.

 

[Thayne]

I'm pretty sure the control channel would be followed by any EDACS scanner, since many systems have analog and provoice groups on the same system.
I was just thinking that it may be possible to make an "add in" DSP for provoice that could be hooked up to an EDACS capable scanner.

I bet somebody has way more knowledge about it than I do.!!

 

[Forts]

I believe every scanner I've used on an EDACS system with ProVoice has ignored the digital talkgroups. Within the past year I've used a Uniden BC780, 250D and a Pro-96 on my local EDACS system (PD is actually AEGIS digital). I've also used it on some nearby systems that use ProVoice... Same result, the digital talkgroups are ignored completely. The only exeption to the rule that I've come across has been my Pro-92 and Pro-2067. They occasionally get hung up on the digital talkgroups, showing garbage info for the talkgroup ID and letting little bursts of noise thru.

 

[wwhitby]

My BC245 ignores the digital talkgroups. However, if you want to see what they are, use T4Win. It will show the digital talkgroups, but it won't let you listen to them.

 

[Thunderbolt]

I believe every scanner I've used on an EDACS system with ProVoice has ignored the digital talkgroups. Within the past year I've used a Uniden BC780, 250D and a Pro-96 on my local EDACS system (PD is actually AEGIS digital). I've also used it on some nearby systems that use ProVoice... Same result, the digital talkgroups are ignored completely. The only exeption to the rule that I've come across has been my Pro-92 and Pro-2067. They occasionally get hung up on the digital talkgroups, showing garbage info for the talkgroup ID and letting little bursts of noise thru.

I have experienced the same thing while trying to monitor some of the ProVoice talkgroups on local Livonia TRS. My 780 will completely ignore them but will pickup the analog ones just fine. I believe the 780 is designed to ignore the digital data and will skip over it.


73's

Ron

 

[Dog]

I guess I was wrong in my first post. I thought the control channel data was what Pro Voice did differently. Isn't all data on the control channel digital? If so why would it be different for digital and analog talk groups on the same system? I guess I am still confused about how it all works.

Back to researching Pro Voice when I get some more time.

 

[Forts]

The control channel is indeed digital, but it's completely different from digital audio formats such as APCO, AEGIS or ProVoice. Those are modulation schemes that the radio specifically need to know how to handle. A scanner such as the 780 doesn't know what to do with them, so it just ignores them. It is entirely possible that someone could come out with a ProVoice scanner provided they don't tromp on GE/Ericsson/Ma-Com's patents. If it's a proprietary format, they can keep it pretty much to themselves. APCO is more like an open source format, where the specs are there for anyone to use. Then encryption is a whole 'nuther story. If you have the proper vocoder, you can indeed listen to ProVoice 'clear' transmissions, but they could also be encrypted. I did some experimenting with an LPE-200 on a local system where the PD used ProVoice. One talkgroup was clear, one was encrypted. I was surprised to hear that the LPE allowed the encrypted audio to pass thru, it didn't mute it. Of course it was completely garbled and un-intelligible. Hope that helps a little! Oh, and for what it's worth there have been several rumours of Uniden coming out with a ProVoice capable scanner in the future... I'm not exactly holding my breath, but I sure would love to see it.

 

[scannerfreak]

Anyone ever hear anything about that guy on that web site(can't remember which one) about an announcement about an Uniden Pro Voice capable scanner? Said he would at the next "coffee meet" If I remember correctly.

 

[Thayne]

The reason I thought this might work is this:

About 2 years ago when colo first started the apco-25 system they were still using 3600CC with the apco-25 modulation. (Since converted to 9600 CC)
My BC-895 would show and follow the talkgroups, but of course no audio except for a short burst of white noise. This friend of mine that helped me do the Disc. tap put together a small project on a proto-board that connected to the disc tap and decoded the apco 25 audio. He since has died, and his wife got rid of all his radio stuff. (At least she gave me his oscilloscope and signal generator!)

Anyway, I'm sure he told me that one of the IC's that he used was actually intended for use in a CD player. It sounded every bit as good as my 785-D does now. So my deduction is that since provoice is not encrypted, if you could come up with the right DSP chip then it would be a piece of cake to decode it.
I'm just too dumb to understand the technicalities of it.
Also, I think it could be done by PC software and a fast enough PC driven by Etrunk, (which has already solved the ESK problem.)

You know, some kid from Finland or somewhere came up with the software to decode DVD copy protection--It's just that scanners arent as fun or profitable as movies!!

 

[senss]

Group calls:
---CMD- TT -LCN--Ixx x----tg------- TT:
1110 11 10 LLLL L0xx xGGG GGGG GGGG - AnlgGrp
1110 11 11 LLLL L0xx xGGG GGGG GGGG - DgtlGrp
1110 11 00 LLLL L0xx xGGG GGGG GGGG - Emg AnlgGrp
1110 11 01 LLLL L0xx xGGG GGGG GGGG - Emg DgtlGrp


Hi! This is the code sending by a EDACS control channel to indicate that a communication is CONTINUATING on a LCN.

The scanners available on the actual market does'nt track digital mode (like Provoice, Aegis, VoiceGuard) because :
it only search for command with type part ('TT') equal to analog '10' analog when digital communication equal '11'.

Alain

 

[mr_hankey]

seems simple enough...

we're currently reworking the ESK etrunker code to do dynamic key detection, but i suspect it will be months (if not years) before a giant like Uniden or GRE decides to implement such a feature in a consumer-level scanner...

time to start bidding on ProVoice Radios on ebay!

 

[SCPD]

EDACS-ProVoice

The only issue, mr hankey, is when EDACS ProVoice Digital System's and users begin using radio's with Smart-cards inside them, then even attempting to listen to said systems with hacked access will have the radio denied access almost imediatly. I am thinking, Uniden will devolope a ProVoice friendly scanner soon, they already were first to do Open Sky. But what's more important then ProVoice is the ability to track Multi-net LTR. In My Book. Which will be scannable first?!!

 

[Forts]

It would be nice if there was a way with ETrunker to determine if a digital talkgroup was encrypted, but from what I have read in other threads it doesn't seem to be possible. Apparently they don't use any sort of status bit to indicate encryption like Motorola does. It could be a big gamble to shell out $1500 for a ProVoice capable radio, only to find out all the talkgroups are encrypted

 

[EricCottrell]

Hello,

The local transit authority is going from conventional to ProVoice. This will be the first EDACS system in the Boston Area although Worchester, Ma and Manchester, NH have Analog EDACS.

I think one problem of a hobbyist decoder is to get the vocoder part. It appears that the Vocoder is the same as P25 but the modulation of the digital stream is different. I was wondering if a workaround would be to remodulate the ProVoice digital signal as a P25 digital signal and use the digital card from uniden. This type of transcoding is used in other areas like digital video.

Multinet LTR is on the way using the Trunker Program as well. I was surprised at the number of downloads of the betas. An university in Boston uses Multinet LTR for their services. Some people can scan Multinet now with two scanners and a computer. Multinet has "encryption" on the control channel which can be determined by looking for known patterns. A similar method could be applied to ESK.

73 Eric

 

[Thunderbolt]

Anyone ever hear anything about that guy on that web site(can't remember which one) about an announcement about an Uniden Pro Voice capable scanner? Said he would at the next "coffee meet" If I remember correctly.

That sounds familar, like I read it on Usenet. However, did you read the one about the guy who had the Uniden TETRA mobiles?
That was a scam and a half.

73's

Ron

 

[12VoltInstaller]

This is from that site

WE ARE SOL!!!!!!
Ok got this off a scanner website for another state:


Uniden...... Provoice digital scanner ???

I was very sad, but not too surprised, to see NO announcements by Uniden at the Consumer Electronics Show that just ended in Las Vegas of any new scanners on the horizon.

Do they really have nothing in the works?

Uniden said:

"NO ........ Uniden is driven by customer
demand, and doubt the demand is there yet for
such a unit capable of decoding that system."

And Uniden said:

"Our employees sign confidentially agreements..... I can not discuss this matter further"


in the near future Uniden is not an option, Now let's bug GRE

 

[Thayne]

I just wanted to thank everyone who added to this thread. I think many of us benefit from the diverse knowledge out there.

Since more provoice systems will be coming online, I'm sure a way to hear it will follow. I remember when EDACS first appeared here around 1991 it took about 2 years before a scanner for it came out.
I drove 30 miles to get a PRO-2052 the day after they came out, then lied to the wife about how much it cost. (She found out anyway--"You paid $300.00 for that little thing??"

 

[12VoltInstaller]

IDEA....maybe

Uniden said:

"NO ........ Uniden is driven by customer
demand, and doubt the demand is there yet for
such a unit capable of decoding that system."



Think we could Email Uniden till they cant take anymore on how much we really want this scanner for EDACS. Maybe its true, maybe they dont know how much thier "CUSTOMERS" want it.

 

[robsterw]

thats a good idea.

post some phone numbers and email addresses for uniden and GRE and i will start hounding them