MDC / Scan / DPL Issue?

[joes243]

Hello-

I was wondering if someone with access to an APX7000 and a repeater with DPL can test something for me. I have my APX7000 set up for Leading Edge PTT ID with preamble disabled. If I quickly press and release the PTT and don't allow enough time for the ID to send, I think it puts the radio in some funky state. I notice a short delay in unmuting the next time the PTT is pressed and the ID is sent on any channel. If in scan and your Tx channel is using a DPL, the radio will sometimes not unmute after a valid PTT. If I take the radio out of scan, it will unmute but after that short delay. This does not happen on tone pls. If I power cycle the radio, all is well again. I am thinking the only workaround for this is to enable preamble so the ID always sends even on a quick PTT press, but it is against our dispatch standards (I guess they don't like the annoying sound). I tried changing a lot of settings but can't seem to find what could be causing this. Is there anyone that can test on their radio (I only have access to 1) and let me know if you have the same issue?

THANKS!

 

[kondoros]

Hi,
a good start would be to check the DOS Coast Time.
This setting is located in Conventional Configuration -> Conventional System -> Features -> Data Operated Squelch Enable

 

[joes243]

Thanks for the reply. I disabled DOS and had the same results. I am attaching a video to better explain the problem. Channel 1 is a TPL, Channel 2 is a DPL. I didn't show in the video if I take the radio out of scan it would unmute on a quick PTT.


[video]https://onedrive.live.com/redir?resid=3E5DB4002AD7B762!29966&authkey=!AIzS6plKNLFxSGc&ithint=video%2cmov[/video]

 

[motorola_otaku]

Early revision firmware in the radio is going to be my first guess. Improper DPL deviation on the repeater/base on the offending channel would be my next guess.

 

[joes243]

I am using FW 14.00.03 and it happens with 3 different DPL repeaters and only while scanning. It had something to do with the radio not being keyed long enough to send the MDC ID. If enable preamble or disable the ID the radio will unmute 100% of the time.

 

[Notarola]

It might be a glitch in the processor configuration its self. When you hit the PTT quickly the radio is supposed to keep the TX active for the duration of the MDC burst. What appears to be happening is that the TX drops when you unkey rather than doing what its supposed to. To add to the fun the processor has the uncompleted "MDC TX window' task still in its buffer, until this is cleared the unit still wants to finish that task. Thats why turning it off and on fixes the issue. For interest sake I bet if you do a proper MDC transmission the issue will clear as well.

This may not be fixable as it might require a rewrite of the various timing and priorities for the processor when dealing with MDC.

 

[motorola_otaku]

What gets me is, I can recreate the exact scenario he's describing - repeated channel with split DPL and MDC enabled, scan on, and quick-keying - and I have never observed what he's describing. Even back in the bad old days of R02 firmware when wide FM receive was buggy as hell it never happened. I run my MDC systems pretty straightforward - 500ms pretime and DOS disabled with everything else at default. I do have status/message, remote TX, radio check, and radio inhibit disabled.

 

[joes243]

You can create the problem otaku? At least I know it is not just my radio. The weird thing is that is only DPL and while scanning. No problem with TPL except for a slight unmute delay. Not too safe if someone bumps the PTT by accident. It seems to unmute after 4-5 seconds after a valid PTT/MDC.

 

[joes243]

For interest sake I bet if you do a proper MDC transmission the issue will clear as well.

It doesn't. After a quick PTT a valid PTT/MDC does not unmute. It shows that in the video.

 

[moetorola]

I would Open a case with Motorola.
You said with preamble checked it does not do it? Correct.

I would check preamble, Until problem is resolved. I set preamble any way with pre ID anyway.

 

[joes243]

Yes, if you have preamble enabled and you press and release the PTT it still sends the ID after the pretime so there is no issue. That is the only work around besides not using a Leading Edge MDC ID.

 

[Notarola]

motorola_otaku - he is running with no pretime.

I supect its the no pretime that is causing the issue. Joes243 try setting the minimum pretime the CPS will set and see if the issue clears up.

 

[joes243]

The CPS will allow 0 in MDC System Pretime. I can't test right now, but I am sure setting it to 0 will clear it up as the ID will send as soon as you PTT.

 

[joes243]

motorola_otaku - he is running with no pretime.

I have pretime set to 500ms...



I supect its the no pretime that is causing the issue. Joes243 try setting the minimum pretime the CPS will set and see if the issue clears up.

 

[moetorola]

I have always added a little pretime and also a preamble of 2 for use thru repeaters when using pre ID.

 

[Notarola]

I have always added a little pretime and also a preamble of 2 for use thru repeaters when using pre ID.

good points.