L A County Metro Trunk Frquency Birdies?

[Rt4957]

For a couple weeks I have been having a problem monitoring the Bus Frequencies for L A Metro (I work for them as well) With my Uniden BC396XT
When a radio transmission is finished,the frequency is still locked up with what sounds like either an open carrier,or an open mike,,but it does not seem to affect the controllers at the dispatch center.

Does anyone else monitor Metro,and if so,,have you noticed this problem?

It`s aggrivating to me as I have to either hit the Scan button or else "Twist the Knob" to get off of the locked up channel.(Not wanting to wear out my scanner by doing this)

I`m way new to trunking scanners,I let the computer do the Programming work,,and for months it was working fine,,just lately been having this irritating problem.

Thanks for any suggestions or help.
Rt4957

 

[LAflyer]

Seems OK this end on a pro-106.

However since you say you work for them, any added insight you can provide to the talkgroups especially for the bus operations would be appreciated. Many of the listed descriptions in the DB are a bit generic. I suspect talkgroups might be divided along the MTA divisional boundaries and possibly garages or even routes.

 

[Rt4957]

When it comes to talkgroups and such,,I`m TOTALLY in the dark,,I just hit the Download to scanner button on these,and let the computer do the rest.

On thing I can try and add,,There was a time that the controllers in the dispatch center were set to certain Divisions (Or Sectors as they called them until abolished a few months back) but the workload of some was a bit overwhelming,,so now it is taken "Next in Qeue" off the computer screen.

I`m still curious as to my birdie problem as the radio will sometimes stay locked on the carrier until it stops,,or else I hit lockout (Which I really do not like to do).

It seemed (Although I haven`t a clue to if this is the problem) that the offending frequency that would flash on the display was 938.200,,but then a couple others were doing it too so that theory went away.

Oh well,,I just hope I dont wear out the "Scan" button having to hit it when it locks up.

Phil

 

[cousinkix1953]

Make sure the DELAY feature is turned off on a trunked system.

Not all scanners will track a 900 mhz system either...

 

[Mike_G_D]

Simple - this comes up VERY FREQUENTLY -

On Uniden scanners make sure that the END CODE DETECT is ENABLED. There is a separate setting for digital and analog. I would use the End Code Detect for both, especially for busy systems.

GRE units do not have a Digital End Code Detect for mixed mode 3600 baud Motorola trunking systems but do have analog End Code Detect settings for those systems and do have Digital End Code Detect for 9600 baud P25 trunking systems (which are fully digital mode only).

Do a search on this site for Uniden End Code detect and you should find a number of threads on this.

Sometimes on trunking systems, a system transmitter will hang open after a transmission ends; the subscriber radios detect and use the end codes sent after the transmission ends and so have no issue. Scanners do not always use these codes and instead rely on the carrier to drop which causes issues if the carrier DOES NOT drop, of course. For Motorola 3600 baud systems having a mixture of analog and digital users, the newer Unidens and GRE units have settings to enable the detection and use of the analog End Code but only the Unidens have Digital End Code Detect settings which are user changeable (for 3600 baud Motorola systems). Because of this, at very busy times the GRE units can sometimes have issues with digital users transmissions ending right when a subsequent analog signal pops up on the same voice channel causing the listener to hear the subsequent analog transmission which has nothing to do with the intended talk group being listened to - the only way to deal with this for GRE users is to press the SCAN button and force the scanner to scan. Unidens have the advantage here IF the user understands the settings and knows how to properly use them.

Modern GRE and Uniden trunk tracking scanners including the BCD396XT will easily monitor 900MHz trunking systems so that is definitely NOT the issue.

-Mike

 

[SCPD]

You may also have interference from an electronic device nearby. A computer, a printer, or even an FM radio tuned to a particular frequency that causes interference in your scanner. In spite of the price for scanners, they are not as well shielded as commercial land mobile transceivers and pick up lots of interference. When your scanner picks up this interference let it lock up and then start unplugging those other electronic devices near the scanner one device at a time until the culprit is identified. Sometimes there are devices in other rooms causing the interference.

I recently found that after I moved some power cords around the back of my scanners/ham rigs I had some very annoying interference similar to what you describe. I have so many cords behind my radio rack that it took quite some time to find which cord was causing interference. I moved my cords around one at a time and found that the computer link cord for the scanner picked up interference from one of the wall warts in one of my power strips. After rearranging this one cord the interference stopped.