DOITTT 800mhz ID's

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leaf

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hi guys,

So I have been scanning the NYC DoITT quite a bit the past few days, trying to find something different from my local precinct.
Couple questions about the organizations using this, hopefully you guys can help me out.

Something keeps popping up loud and clear with ID:33008..Seems to be come sort of dispatch/command center, and I have heard a few calls come in where people in the field are checking license plates and such. Is there any way I can find out who this is with the ID number and what does that number mean?

I also get EMS MVO(32288) very loud and clear, but cant quite figure out what they are doing. Maybe dealing with maintenance and care of the EMS vehicles?
 

mike4164

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The MVO for EMS is the drivers who transport the vehicles to and from the stations for repairs. The license plate checks are probably the NYC Sheriff. If you are looking for something on the Pct. level for NYPD you wont find it there. The Pct.'s use the 400 Mhz channels that are in the data base.


Mike
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FDNY/EMS HAZ-TAC
 

leaf

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hey mike, thanks for the response.
Nah, I wasnt looking for anything precinct level, actually the opposite. The precinct stuff gets a little boring to me sometimes.

so with the ID: number.... is there any way for me to find out what those ID #'s are? I don't understand why those ones show up as just that number, and others show up with a name. I do realize the ones that show up with a name are actually programmed into my scanner... and these other ones may not be... But how does my scanner hear them then?

Thanks so much.


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dpcain

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Your radio will pass through any transmission on a talkgroup you're listening to, regardless of what radio ID they have or whether it is in your list or not. If you have the capability to park on a radio ID instead of a talkgroup, though, your radio will instead of searching for that talkgroup's activation will only search for that radio's activation regardless of talkgroup.

If you don't already know what radio IDs are who, just keep listening- it's a fun little SIGINT exercise to figure it out. Of course, if you end up making a pretty good list, it can always be added to the wiki for the benefit of all. For example, the page I mostly contribute to: Maryland FiRST Radio IDs
 

leaf

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OK, cool. I will definitely start making a list and notes...
I guess I'm a little confused about the difference between a Radio ID and a talkgroup. I will read up on this in the 396XT easier to read manual. Thanks for all your help guys


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dpcain

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For your clarification:

A talkgroup is a transmissions net. Best explained by the following steps:
1) User of a radio (say radio ID 1121984) selects a 'net', for instance "USCG NY (talkgroup 11856)" on the DOITT sys, and pushes the button to transmit.
2) Radio 1121984 sends a message to the system requesting to talk on TG 11856, and the system grants it.
3) As part of the info it's always transmitting on the control channel, the system sends a message saying TG 11856 is active with voice on a particular output frequency.
4) All other radios on the system that have "USCG NY" (aka TG 11856) selected or scanned by the user silently switch to that output frequency to listen for voice traffic until they time out or the transmission-end signal comes across there.
5) Radio 1121984 opens the mic and transmits the user's voice across the input frequency to the system. System rebroadcasts that voice transmission across the associated output frequency to all radios listening there.
6) Radio 1121984's user un-keys, the system sends the end-traffic signal, and all radios revert back to the control channel to 'listen' to and decode data, waiting for someone else to start the process that will send them back to an available voice frequency for the reply.

This all happens in the fraction of a second between when you push the button on the radio and when it says 'PING' to say you can go ahead and talk. For the receiving radios, it's essentially a silent process until their speakers break squelch for the received voice transmission on the output frequency.

TL;DR: So basically if you see a talkgroup ID, that's a voice net that radios can switch to like an old analog frequency. The RID is the actual identity of the radio transmitting, which can be instrumental to see in discovering who's who and what new talkgroups are being used for.

Hope that helps explain the difference and also gives some clear idea of the mechanics behind that. The above paragraph would probably have sufficed, but I think it's better to have a stronger understanding involved.
 

AlexC

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4) All other radios on the system that have "USCG NY" (aka TG 11856) selected or scanned by the user silently switch to that output frequency to listen for voice traffic until they time out or the transmission-end signal comes across there.
Not exactly the case with scanning. The only way talkgroup audio comes across a site (regardless if it is simulcast, intellipeter, etc) is if a subscriber is affiliated (requesting) the talkgroup or if the talkgroup is requested on the site you are listening on (always heard on that site regardless of subscriber affiliation (based always on available capacity to carry). This is based on the programming on the controller level and is not controlled by a subscriber.

This is why you will find a lot of public safety agencies do not program dispatch channels to have scan or Chief's only to have scan. You can easily miss traffic on your system if something is not requested on the site the radio is affiliated on.

If your system is a large simulcast and single zone you will hear all talkgroups on the system as long as one of the two conditions above are met.

Alex
 

leaf

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Wow., thanks for the detailed responses. I'm going to read and reread this stuff... Now at least I have a better understanding of it. Thnx
 
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