Trunked System Discovery and Signal Strength Bars

[smcbmt]

When scanning a trunked system will the signal strength meter show bars due to the data from the control channel frequencies whether there is any talk group activity or not?

If you run a Discovery on a programmed trunked system and there are no signal strength bars then the system is out of service or out of range and it’s a waste of time to run the Discovery?

I should know this but it just occurred to me. Thanks!

 

[Enjoi19]

When scanning a trunked system will the signal strength meter show bars due to the data from the control channel frequencies whether there is any talk group activity or not?

Yes, when sitting on the control channel waiting for talkgroup activity it will constantly show signal strength as it's receiving data.

Someone else will have to chime in more familiar with the discovery option - but I would presume if it's not showing any signal, it's not receiving anything. Perhaps try it on a known receivable site to see how it acts.

 

[smcbmt]

At least for P25 trunked systems it appears when running Uniden‘s Discovery looking for talk groups and activity no signal strength bars doesn’t necessarily mean the system is defunct or out of range.

On the system of interest I got 2 hits as soon as I started Discovery. So I started watching. There were no signal strength bars then in less than 2 minutes 1 bar appeared along with DAT then no bars as pictured. Another minute of no bars and again 1 bar and DAT appeared. Back to no bars then 2 bars and a TGID# popped up and was received.

To me that means, at least on P25 systems, when running Discovery mode, no bars isn’t necessarily bad. But not seeing at least 1 signal strength bar and DAT within a few minutes is bad. You’ve either not programmed in a control channel frequency, the system is defunct, or you are simply out of range.

 

[BinaryMode]

Which scanner? Discovery Mode - The RadioReference Wiki

The control channels will have a constant flow of data and thus DAT will be displayed. The voice channels only have data when there's actual voice...

Trunking Discovery Mode allows you to monitor a trunked radio Site for channels not currently in the database.
It can automatically record audio and log newly discovered channels for later review and identification.

I'm assuming that means voice channels.

 

[smcbmt]

Which scanner? Discovery Mode - The RadioReference Wiki

The control channels will have a constant flow of data and thus DAT will be displayed. The voice channels only have data when there's actual voice...



I'm assuming that means voice channels.

BCD536HP — I used trunked discovery to uncover new talkgroup id’s. Typically when I run a trucked discovery I set it up to check the database and record 120 seconds of conversation on new tgid’s. I use these snippets to try to ID the who / where. Sheriff or PD, utilities & pollution control or styrene unit, etc.

the particular chemical plant I ran the test on is a 900 MHz system 3.25 miles away. For my back of the set antenna it’s pretty obvious from the signal strength bars this is close to the limit of my ability to receive.

The test was prompted by another chemical plant 6.5 miles away running an 800 MHz LTR system that I just haven’t been able to determine the LCN’s or hear in any way. This trial taught me since I see and hear nothing from the LTR system it’s just not receivable by my setup. The plants aren’t concerned whether their signals reach much further than the fenc unlike first responders.

 

[BinaryMode]

The following may be of interest:

The only magazine devoted ENTIRELY to scanning

EDACS - The RadioReference Wiki

wiki.radioreference.com