Batboard

Hello all,
Can someone please explain how DPL works, as opposed to PL. Also what is reverse tone burst?
Nick

DPL is a small data word that is sent like PL - subaudible. Unlike P.L. it is decoded more rapidly then PL. In PL they used a reverse burst to quiet all recieving radios so there aren't any squelch bursts... in DPL they use a 134.4 "PL" tone this is recognized by the recieving radios as a mute or quiet command to acchive the same thing. If you have a community repeater with PL and DPL users never use the PL tones near 134.4... since any of your DPL users may false the PL users when the DPL 134.4 goes out.

MicorRT, one error DPL is slower to decode.
The DPL code is sent as a low frequency square wave data stream of ones and zeros, the receiver decodes the transisions from one to zero and zero to one, so the wave must be kept symetrical.

<font size=-1>[ This Message was edited by: Will on 2002-03-25 23:19 ]</font>

thanks guys, very interesting. and a pritty good way of doing it. must admit tho i like the tail. and no im not one of those guys that sets up mdc just for the noise, 5 tone selcall maybe but not mdc, i use the DOS.
nick

The DPL code is actually a 9-bit code with synch and check bits added. There are 3 bits per digit for all three digits. The rest is for protection against falsing. If the radio used the old code plugs and you wanted to change codes, you could make a plug using jumpers - if you knew which pins were used for which digit.

Thanks to all who responded to my query. One point that should be made is that reverse burst is very seldom, if ever, used in amateur radio transceivers. One reason why I use a commercial radio on the ham bands is to spare other users from hearing a squelch tail when I unkey. (Both the 2m repeater and my radio are made by M.) A number of users have noticed the silent muting.

The silent muting feature is really great - it seems that more and more ham portables/mobles are being made without the reverse burst feature.

If you want a good portable that does to do this, look at the HTX-202 and HTX-404 - the old Radio Shack bricks. They handled this quite nicely.

-Alex

Just thought I'd warn everyone about the Motorola Moxy... it is pretty much just like a Motorola Maxar... except the Moxy lacks reverse burst on PL as well as on DPL!

Just thought I would share this info.

One Ham rig that DECODES nicely (ie it will mute on a Motorola reverse burst PL) is the ICOM 2GAT. Most Yaesu Ham rigs are slow at decoding PL (and false too) but they do have DPL which seems to work good and it does send the 134.4 PL burst at the end of tx. If the Ham repeater you are working has a poor decoder, it will be of no help to send reverse burst....