MCX1000 DPL scan problem

[talkpair]

I have 2 different MCX1000 radios that I use for scanning only.

They usually, but not always fail to stop on a valid DPL code when scanning.

The CSQ and TPL coded squelch work flawlessly.

The DPL decodes properly and audio is heard when NOT in scan mode.

Due to co-channel users in distant cities, I don't want to change this to a CSQ channel.

Any workaround or option that i'm not aware of ?

 

[RKG]

I'm not intimately familiar with the MCX1000, but I suspect I know what your problem may be.

Unlike PL (which is a continuous sine wave at a specific frequency, which can be "entered" for decoding at any point), DPL is a digital stream consisting of the bits representing octal digits 4XXX (where XXX is the DPL code of interest), plus some error correcting bits. In order to correctly decode this bit stream, you have to know where it begins. DPL decodes find the "frame" of a DPL "word" by pattern recognition.

The problem here is that while there are 512 different DPL codes theoretically available, only 83 of them are considered "valid," because the others have bit patterns that can be confused for something else if the radio begins looking at them in the middle of a DPL "word." This usually happens if the radio lands on a channel, decodes valid freq, and then begins looking at DPL bits in mid-stream.

You can find the "valid" DPL codes at the Midian website. I suspect the channel that is giving you problems is using an "invalid" DPL.

 

[LANEWZ]

We had a problem decoding DPL 516 on a UHF XTS 3000. Turned out the Vertex 920’s were putting out an insufficient level of DPL. It only caused a problem when the radio would be put into scan.

In addition one of the Fire Watch repeaters also had the same issue and required radio service to go up and increase the DPL level. Problem solved.

This only seems to occur with Motorola radios when scanning.

Hope this helps