Discriminator

[wildbillx]

Can some explain to me what a discriminator does when installed in a scanner. I understand trunked systems and have 3 trunking scanners. Also is there any way to get what the pd/ems/fd write on there onboard comp. or MDT's?
Thanks

 

[SCPD]

It allows you to decode the trunked systems data string. It is illegal to intercept MDT's in the USA under federal law.

 

[wildbillx]

what is the systems data string.

 

[ka3jjz]

A discriminator - or more to the point, the output, since we're talking about it being used in Trunker, and other similar programs, is briefly described here...

http://wiki.radioreference.com/index.php/Discriminator_output

The 'Trunked Data String' , as AC7XC refers to it, contains all the control data pertinent to tracking, and maintaining, the status of the trunked system and all the units that connect to it. Thus, if you read this data, you can find out all talkgroups that are being used in the system, the system's ID and other useful features. 73s Mike

 

[DickH]

Can some explain to me what a discriminator does when installed in a scanner. I understand trunked systems and have 3 trunking scanners. Also is there any way to get what the pd/ems/fd write on there onboard comp. or MDT's?
Thanks

Every FM receiver (including your scanner) already has a discriminator. That is what detects the audio so you can hear voice. People "TAP" the discriminator output before the audio filtering to obtain the unfiltered data from the control channel and feed it into a computer where a program "reads" it and displays info.

If you understand trunking, then you know that the control channel carries the data stream that you seem confused about. That data tells your scanner to change freqs. to follow a conversation as people key their mics.

 

[wildbillx]

so if I "tap" mine and I listen to Deleware State digital the program on the computer will show me what the talk group name is and not just the dec code. Is there anything else it does? I am in an area where there is not much trunking so I want to know what benefits it has before opening the scanner. THanks

 

[DickH]

so if I "tap" mine and I listen to Deleware State digital the program on the computer will show me what the talk group name is and not just the dec code. Is there anything else it does? I am in an area where there is not much trunking so I want to know what benefits it has before opening the scanner. THanks

I use the old "Trunker" program and it does not display TG names, but it does show individual radio IDs, like 710496 along with TG, freq. and a few other things. Since my system never changes I almost never use Trunker now.

I would not advise "tapping" your scanner. Try to find an old 800MHz capable scanner on e-bay or a pawn shop or somewhere. It will be cheap and much easier to do than a newer one. And if you ruin it, no big loss !

I don't know what programs can do digital. Also, depending on the program, you may need a Data Slicer to process the signal so your computer will recognize the data. Search around the Internet for info. Look at the Software section of this RR group.

Come to think of it, there is a fairly new program called ID Tracker that may be good. There have been some posts here about it.

 

[wildbillx]

THanks for all the help, I think I will pass on tapping a scanner for now, unless I move near a big city. Thanks again.

 

[SCPD]

It is illegal to intercept MDT's in the USA under federal law.

This is a bit simplified.

If it's CDPD or encrypted (and as of 2006 all law enforcement are required to use encryption to be allowed NCIC access) then it is illegal to intercept. Otherwise it's merely illegal to disclose whatever information you discover.

There are some other nuances ... but you're best bet is to search the federal and state criminal code for your area. Don't take mine or anyone else's legal advice from this forum !

-rick

 

[wildbillx]

???

So does that mean I can get info through the discriminator?

 

[SCPD]

So does that mean I can get info through the discriminator?

Let's see ... here's your original request from the post starting this thread.

Also is there any way to get what the pd/ems/fd write on there onboard comp. or MDT's?

You're asking to intercept the police, fire and ambulance mobile data computer traffic.

There was an initiative by the FBI more than a few years ago called NCIC2000. The purpose of this initiative was to mandate relatively strong encryption of all federal, state, and local computer networks that access the NCIC database. The drop-dead date for encryption was either September 2005 or January of 2006 (sorry, I can't remember which). Details are in the Federal Register. At about the same time, a new federal law called HIPPA was passed that placed conceptually similar requirements on computer networks that handle patient data (like EMS). The cut-off date for encrpytion there came and went two or three years ago. Basically, you should expect police and medical mobile data to be well encrypted. Any software that you might find to decode such data won't handle the encryption.

What else can you do with discriminator audio?

1. If you dig around, you'll find software to decode other (insecure) forms of mobile data used by private business (taxis, trucking, etc.)

2. The airlines and air freight use a low speed data signal called ACARS. There are programs to decode that.

3. The railroads use a low speed data signal called ACTS. There's a program or two for that.

4. You'll also find programs for text and numeric paging. In some countries (like the Netherlands) it's legal. If the paging service is offered by a common carrier then it's considered off-limits by USA federal law.

5. There are a handful of programs for decoding the five major trunked radio protocols - plenty of info in this forum on that.

6. There are also a handful of programs for decoding tone and sub-audible data (like MDC1200, DTMF touch tones, CTCSS/PL tones, and DCS/DPL data) on voice channels.

-rick