DPL's

[gpdexplorer 46]

I know what a PL is, but what is a DPL?

D for Department?

Thanx

[x242Steve 1]

Digital Private Line

[IzzyEng4 427]

DPL's came about I think in the 80's or 90's (maybe earlier) to give two-way radio users "more" channels. Another words if you have a large city or regional system that has four separate channels, with PL's you can make more user end channels so they don't interfere with a neighboring department. When the regional radio coordinators started to run out of options, the radio manufacturers started to create the DPL's since there was no more PL space and new technology was available. The PL's are an analog, inaudible frequency that the radio listens for when you transmit. The DPL's are the same but use more modern circuitry.

You can tell the difference between PL's and DPL's. PL's usually are two to three numbers with one number after the decimal point. An example would be the PL of 123.0 (this is a real PL's number ) A DPL is always three numbers and can start with a "0". A couple of examples for this is 074 or 331. Most scanner books may add the letter "D" before a DPL number so a reader will know the difference.

Hope this helps you out a little on the history of it.

Also as always if I missed something or my info is wrong let me know. Thanks!

[Skooter92 7]

PL stands for Private Line, which is Motorola's version of something called Control Tone Coded Squelch System (CTCSS). It's a subaudible range hertz tone which is transmitted along with the audible voice and decoded by the receiving radio. DPL is Digital Private Line, which is actually a digital sequence of information, again sent inaudibly along with the audible voice in a transmission. The advantage of DPL is that it's not subject to shifts in frequency of the tone generator which can affect the receiver's accepting the tone to open up for the signal. DPL's come in two flavors, standard and inverted. If you see a DPL listed as, (for example), "D413I", this is an inverted DPL. Some PL/DPL capable scanners don't accept inverse DPL's (some of the old ones, I believe!).

Different manufacturers have different names for all these, like Privacy Guard, Channel Guard, Private Line, etc, but they all use the same basic analog or digital scheme.

Edited January 15, 2006 by Skooter92

[gpdexplorer 46]

Thanx for all of the info guys