MSHP Mobile Extender

[BaLa]

Quick question about the Mobile Extender/Vehicular Repeaters in the Hwy Patrol Cars.


You can hear dispatch through the frequency (148.6).
When there is a transmission on the dispatch channel it sounds like the repeater cuts out every 1-2 seconds.
The best way to explain it, is that it sounds comparable to having priority set on a scanner.

Why does it do that?
and anybody else notice this?

 

[jayres]

The best way to describe it is priority sampling... The carrier on the mobile extender "drops" every 1-2 seconds to see if the portable is TX'ing... if so, then it kicks the mobile into transmit....


I have some of the surplus lowband MSHP radios with the VHF extenders that I've done some "Frankensteining" on and have a VHF Mobile with VHF extender... Works nice out in the BFE parts of the county!

 

[BaLa]

thanks, I guess that means I'm not 'hearing things'

approximately how far does it reach?
A lot of times I hear the repeater, and don't see a car anywhere in sight.

 

[clayman]

It depends on the receiver & terrain, but I get them on average 2-3 miles away. It's a nice way to know if a trooper is in the area/there is an accident ahead. You can also tell the difference between an extender and the trooper's portable by the presence or absence of the priority sampling. Also the portables have a PL tone of 100.0 if I remember correctly
Clayton

 

[mburdette]

Dumb question: When I first programmed 148.6 in my Pro-97 over a year ago ,I heard some traffic and saw 203.5 as the PL tone, then just went ahead and pressed enter for that tone. Have I been missing things ?

 

[jayres]

Well, yes... you are missing things... the extenders (car side) do not transmit PL... the portables do transmit PL... The reason for this is so when multiple extenders are on within range of each other, they don't key each other up and lock up the system. There is logic sampling in the extenders that *in theory* keep there from being multiple extenders enabled at a location, however it doesnt always work like it should...

 

[mburdette]

Thanks, jayres. I have been in the habit of entering the PL tones as they come up on the things I enjoy listening to, once I can tell they are consistent and not just false readings. It cuts down on interference from electrical and other sources. However, this is probably not the only case where I am also missing some things where the PL tone is not used. Thanks again!