Posted by Joe on October 26, 2001 at 19:23:49:
In Reply to: 2 part Question posted by Michael on October 15, 2001 at 17:39:16:
: When listening to WSP. How is that other
: cars can not hear each other but the
: Disptacher can hear them. Or do I have
: been close enough to listen to them.
The dispatcher has multiple high elevation base stations with wireline connection back to them. So they hear through these sites, effectively covering a wide area.
The mobiles are on the ground, so you would need to be within range of the mobile to hear it on the channels where they work "simplex", such as South King County (154.680). Also, a mobile on one side of the area may not hear a mobile on the other end of an area, despite the fact they use high power VHF radios.
In the case of North King County (155.580) the mobiles are talking through a repaeter (usually) so this is why you hear the dispatcher and the mobiles at close to the same signal strength, as thay are all coming to you from the same locations. There are several repeaters on that channel pair, and the mobiles, like the dispatcher, may choose which site to access for the best coverage
: When listening to the Car to Car talk. Some times you can hear them and other time
: you. don not.
Car to Car is simplex, so you need to be within range.
: PL's I know are Private Line. What does it mean when you post them on the web
: Site.
PL tones are used to shield the receiving radio (base or mobile) from listening to signals on frequency that they do not want to hear. One example is 154.680. WSP uses this for dispatch in Seattle as well as Vancouver Wa (and one other area I think).
In the absence of this setup, the Seattle dispatchers no doubt hear Vancouver Dispatchers, as their sites are high elevation, and I hear Vancouver on the ground in South King County on a good day.
:And do I need to program them in and how do I do that.
You do not "need" them unless you only want to hear a signal that is also modulating a "PL" tone. The only real reason for a scanner user to do this is in shared channel arrangements where you only want to hear certain activity, or for intermod protection.
BTW, that was a four part question!