Spectra MDC mute ("DOS")

[kilocharlie8]

Greetings,

I have some Motorola Spectras using conventional FM which transmit MDC1200 at the end of transmission.

I'd like to be able to pass that audio through to the speaker on the receiving units. Yes, I know this is annoying to some people that have heard these squawks for years, but I like to hear it.

Is there a way to toggle the muting? Currently all my units mute the MDC except for a very brief chirp. I have read on this forum that the feature is called "Data Operated Squelch" or "DOS". I looked around in RSS and I was unable to find anything called this or which even appeared to be similar. We're using full PL on most channels, DPL on some others.

Here are some screenshots of the MDC setup options for my radios.

Thanks for your help,

--E
de W6EL

 

[mbnv992]

Try “muting type”.
Also - under “system delay” how you’re currently is set to 500ms - I would change that to 100ms or less. 500ms will see a delay in the RX audio of your radio.

Ask me how I know.

 

[kilocharlie8]

Muting type set to none means it will not squelch for a specific ANI, but rather, just use PL/DPL. The other choices are basically boolean logic of "PL/DPL OR Unit ID", "PL/DPL AND Unit ID", "Unit ID only". I don't think these are gonna work since it's on None right now (which is just PL/DPL).

System delay is only relevant for beginning-of-transmission MDC, at least according to the Help text. But I can try adjusting it.

 

[mbnv992]

Muting type set to none means it will not squelch for a specific ANI, but rather, just use PL/DPL. The other choices are basically boolean logic of "PL/DPL OR Unit ID", "PL/DPL AND Unit ID", "Unit ID only". I don't think these are gonna work since it's on None right now (which is just PL/DPL).

System delay is only relevant for beginning-of-transmission MDC, at least according to the Help text. But I can try adjusting it.

It’s been many many years since I played around with an analog Spectra so - apologies for the bad intel about the “Muting Type”. But def adjust that System Delay to 100ms. In my HT1000, GP300, Visar, etc all of them had the first .5 seconds of the transmission cut out and couldn’t figure out why until I adjusted that.

 

[kilocharlie8]

Well, the way around all this was to cut pin 39 on U700. This particular radio doesn't (can't) display MDC codes anyway, so the decode capability was not that useful for me. I can't exactly recommend doing this to your perfectly good radio, but it does work!

If you think this is crazy, that makes two of us.

73 and keep having fun,

--E
de W6EL

 

[ff026]

All you had to do was disable MDC signaling on a channel and you won’t get muting, now it’s been a long time since I messed with an analog spectra.

 

[kilocharlie8]

All you had to do was disable MDC signaling on a channel and you won’t get muting, now it’s been a long time since I messed with an analog spectra.

I tried this. Made a purely conventional FM channel without any MDC and it still muted it! I spent a good half hour playing with various MDC-related options in RSS and finally just clipped the pin.

I imagine this was a highly desirable feature in its time, as it makes the MDC seem more transparent.