Vhf MPT-1327 system

kayn1n32008 · #1 (**permalink**) 03-10-2009, 10:00 PM

I have been working in an area that has a Vhf multisite MPT-1327 system that is used by the county for fire/ems, the system is in the database but no other info is listed, talkgroups ect. what would i need to gather this info? i work during the day but if it is relativly easy i would be interested to get something going. i have a vhf radio i could use to monitor this system, what would i need for software?? what mods to the radio would i need to make?? would it be easier with a scanner?? thankyou in advance

k

Comint · #2 (**permalink**) 03-10-2009, 11:10 PM

Quote:

Originally Posted by kayn1n32008

I have been working in an area that has a Vhf multisite MPT-1327 system that is used by the county for fire/ems, the system is in the database but no other info is listed, talkgroups ect. what would i need to gather this info? i work during the day but if it is relativly easy i would be interested to get something going. i have a vhf radio i could use to monitor this system, what would i need for software?? what mods to the radio would i need to make?? would it be easier with a scanner?? thankyou in advance

Well, if you download, and use, TrunkView you would be able to decode the Control Channel, and log the information, just by using 'speaker audio'.

However, it requires one of the 'supported scanners' to be able to 'Trunk Track' the system, and follow the conversations, and to record the conversations as WAV files.

Note: The recording of WAV files may not work on some Win98 / SoundCard combinations.

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Comint

kayn1n32008 · #3 (**permalink**) 03-10-2009, 11:29 PM

thanks, gonna have to get my ducks in a line and get moving on this

kayn1n32008 · #4 (**permalink**) 03-11-2009, 12:09 AM

well i did download it and i am decoding just with speaker audio and the built in mike on my laptop, but what it comes up with for a ccfreq just doesn't add up its vhf but shows 420.000 as a cc freq, im very very new at trunking in general so any help would be great

thanks in advance

citylink_uk · #5 (**permalink**) 03-11-2009, 09:37 AM

Hi,

You first have to set-up the site details in the program.

First go to Options>Site Database. Then add a name for the site, enter the system id (the 4 digits to the left of where it says 420.0000). You then need to enter the control channel frequency that you are decoding.

If the system has a logical channel plan then you need to work out the base frequency: - TrunkView :: MPT1327 Protocol decoder -

If the voice channels don't follow a logical plan, or you can't get the base frequency to work, then you can open the (Settings>) Profile Editor and enter the channels manually.

It may sound complicated, but when you set-up one it comes naturally. If you need any more help please feel free to post, also if the system is in the database post the url to the system in the database and that will help us to help you set it up.

Comint · #6 (**permalink**) 03-11-2009, 08:14 PM

Quote:

Originally Posted by kayn1n32008

. . . but what it comes up with for a ccfreq just doesn't add up its vhf but shows 420.000 as a cc freq,

The program has no way of detecting which frequency you are monitoring, as the Trunking System Controller (TSC) only broadcasts Channel Numbers. The 420.000 is the default value in the program, and is just a placeholder. Once you have set up the Site Database, the CCh frequency listed in the database for that particular Site will be shown instead.

Note that some Sites may change (MOVE) to a different CCh frequency from time to time, and this will NOT be reflected in the Header, as the field is NOT dynamic. If the change is long term, then the Database will have to be edited to show the new CCh frequency.

You mentioned that it is a multi-site network. Does it broadcast 'Announce Control Channel', or 'Vote Now Advice' messages.

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Comint

kayn1n32008 · #7 (**permalink**) 03-11-2009, 11:15 PM

thanks for the info, im not sure what the 'Announce Control Channel' is so i am going to post a log file of a short monitor i just did. while i was playing around last night i did not see anything different than what is in this file. oh yes this system changes cc frequencies, the cc i was listening to last night was silent this morning when i got up.

k it will not let me load a file, i would like someone to look at this file so at this point i will have to send it out by email

Jay911 · #8 (**permalink**) 03-12-2009, 12:04 AM

Please fire it my way. I mucked about with Trunkview for a while, and I'm 99% sure I know what system you're listening to (and would love the chance to get some info on it, like you!) - Yellowhead County, right?

My email is jay911@gmail.com.

If the system is anything like the other MPT1327 systems I've monitored, the control channel will move every 2 hours. When I'm monitoring MPT, I put my scanner in scan with just the trunk talkgroup channels in it. When one CC drops, the scanner will move to the next one (theoretically).

Comint · #9 (**permalink**) 03-12-2009, 01:21 AM

Quote:

Originally Posted by Jay911

If the system is anything like the other MPT1327 systems I've monitored, the control channel will move every 2 hours. When I'm monitoring MPT, I put my scanner in scan with just the trunk talkgroup channels in it. When one CC drops, the scanner will move to the next one (theoretically).

That's one of the problems with MPT1327, there are so many ways the networks can be set up. On one of the local networks, which has 23 Sites, only one Site regularly changes CC frequency, while the rest of the Sites have been on the same CCs for about 3 years.

When a Site is going to change CC, it broadcasts a MOVE command, so the radios don't have to go hunting for the new frequency. The 'Announce Control Channel' message also serves to advise radios that missed out on the MOVE broadcast. Of course, not all networks are configured to broadcast the 'Announce Control Channel' messages.

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Comint

kayn1n32008 · #10 (**permalink**) 03-12-2009, 09:11 AM

Quote:

Originally Posted by Jay911

Please fire it my way. I mucked about with Trunkview for a while, and I'm 99% sure I know what system you're listening to (and would love the chance to get some info on it, like you!) - Yellowhead County, right?

My email is jay911@gmail.com.

If the system is anything like the other MPT1327 systems I've monitored, the control channel will move every 2 hours. When I'm monitoring MPT, I put my scanner in scan with just the trunk talkgroup channels in it. When one CC drops, the scanner will move to the next one (theoretically).

yup you got it Jay, been working out this way for a little while and ya i want to get some info on it. right now i have only been able to play with it for a few minutes. i logged a snippit of data yeaterday.

right now i have no way to get audio to my computer with out using my internal mic so leaving the radio and my computer on in my hotel is just not an option yet. i figure after this trip(should be back home friday) i will be making a patch cable to get audio from my HH to my computer. i am sending you the snippet of what i have any suggestions of how i should have trunk view set-up? right now i really would just like to gather as much data as possible and sort through it later.

jsharp2316 · #11 (**permalink**) 11-05-2009, 03:36 PM

My first question is where in the US are you? I know most of the MPT systems in the USA. Problem in the US is the VHF band is not paired and there is no rhyme or reason to channel layout. They are typically direct entered into the mobiles and the transmitter shelf controllers are told who they are. You certainly can use Trunk View to monitor and get some information about it. Vote now advise will give you control channel and syscode info. Monitoring will identify idents and groups used. You will need to read some about MPT to get a working knowledge of commands exchanged over the air and then monitor to see a pattren. For example a SDM 1 is a short data message sent over the control channel. It consists of a single byte message appended to a command. But it can represent any of 30 different 12 character messages.

kayn1n32008 · #12 (**permalink**) 11-05-2009, 04:20 PM

Quote:

Originally Posted by jsharp2316

My first question is where in the US are you? I know most of the MPT systems in the USA. Problem in the US is the VHF band is not paired and there is no rhyme or reason to channel layout.

Hi,

i am not in the USA, i am in north central Alberta, Canada. The area is about 150+Km west of Edmonton. Thankyou for the message info, not sure when i will be back working in the area that the MPT system is, as the price of natural gas needs to more than double for companies to start drilling and exploring again, infact i have not been back in that area since my last post on this topic