P25 trunking scanners

[emtbls1987]

I’m looking for someone who’s a geek and knows everything about scanners and radios systems or just scanners. Can someone explain to me how a scanner is able to monitor on (p25 trunking system) how it is able to know which frequency that lets say the local police who just started talking on the radio are using and. In better easier terms how are they able to work just about exactly the same as if you had one of the radios that was being used? The scanner doesn’t get info from the Control channel does it?

 

[KevinC]

The scanner doesn’t get info from the Control channel does it?

Yes is does.

 

[iMONITOR]

I’m looking for someone who’s a geek and knows everything about scanners and radios systems or just scanners. Can someone explain to me how a scanner is able to monitor on (p25 trunking system) how it is able to know which frequency that lets say the local police who just started talking on the radio are using and. In better easier terms how are they able to work just about exactly the same as if you had one of the radios that was being used? The scanner doesn’t get info from the Control channel does it?

Trunked Radio Systems - The RadioReference Wiki

wiki.radioreference.com

 

[JethrowJohnson]

Trunking Basics - The RadioReference Wiki
This should explain it pretty well.

 

[rrobinso84]

...how it is able to know which frequency that lets say the local police who just started talking on the radio are using...

As you read up on how digital trunking works, keep in mind that the LEO didn't "just start talking on the radio!" He or she was using a radio that was set to a specific talk group on the system that affiliated with a site and when keyed assigned an available frequency for the transmission BEFORE the start of talking.

It's a fascinating system! Share what you've learned!

 

[emtbls1987]

Trunking Basics - The RadioReference Wiki
This should explain it pretty well.

Yeah I know how a trunking system works just didn’t understand how a scanner could work like a radio as in get info to use from the control channel to be able to know what frequency the Talk Group is using when someone on that group uses it

 

[emtbls1987]

Yeah I know how a trunking system works just didn’t understand how a scanner could work like a radio as in get info to use from the control channel to be able to know what frequency the Talk Group is using when someone on that group uses it

Thanks

 

[emtbls1987]

So I’m theory I could take a P25 Trunked transceiver and program it to do the same thing as a scanner just not transmit or affiliate with any site. I want to use a Bendix King KNG radio that I bought with P25 trunking and program it to of course only RX no TX. Reason why I want to do that is no offense but a transceiver portable or the BK one receives way better. Yes more $$$ thanks everyone

 

[Kd8lzl]

In theory you could program a radio to receive like a scanner to receive p25 systems, but it is illegal and doesn't scan as fast as a scanner. I would just buy a scanner.

 

[hill]

KD8LZL,

It's not illegal to use a real radio to monitor. Just make sure to use NAS.

 

[Kd8lzl]

I'm sorry, I thought it was disregard my comment.

 

[JethrowJohnson]

Yeah I know how a trunking system works just didn’t understand how a scanner could work like a radio as in get info to use from the control channel to be able to know what frequency the Talk Group is using when someone on that group uses it

You just program the scanner by selecting the type of system (P25 Trunk) and program the site (AKA tower or towers) and program the control channels (which would be all of them if it's a Harris system) and then program the talkgroups you want to monitor, and then it will monitor the active control channel and it will tell the scanner when one of those talkgroups becomes active and which frequency to tune to in order to receive the transmission.

 

[JethrowJohnson]

I don't know why most of that paragraph is crossed out but I didn't do that on purpose.