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Thread: XPR6550 "Power Ramping Trigger On"

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    Default XPR6550 "Power Ramping Trigger On"

    In trying to put my low split VHF XPR6550 into service mode, I had a brain cramp and pressed the wrong button to be greeted with the message "Power Ramping, Trigger on". It doesn't appear that there's anything different with the radio, but I've never heard of this and was wondering what it's for.

    If anyone is wondering which button I pressed, it was the very bottom button, 2 below the PTT.

    PS - I did get actually get the radio into service mode.


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    It's not documented in the service manual or the System Planner Guide.

    I have forwarded your question to someone at Moto TRBO Technical Support; he's away from the office for a week. Hopefully he can fill us in.

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    That's awesome! Thanks man.

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    I think it is a service feature that provides an output that allows you to trigger a 'scope connected to a high speed power detector to look at the PA power ramp waveform. Each TDMA burst needs the RF output of the radio to ramp from off to full power and back to zero again quickly, but not too quickly. Too quick (fast risetime) and the signal will splatter into adjacent channels, too slow and you waste the timeslot.

    It's a common service feature on all TDMA systems like GSM, iDEN, P25 PII, etc. It would be neat if Moto documents what pin is used as the trigger output (should be in the service manual).
    Last edited by Astro Spectra; Mar 25, 2013 at 06:21 PM.
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    That's great guys, thanks a lot.

    I never can get too much info from here. I never get tired of the wealth of knowledge that this board provides.

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    Here's the answer from Moto:

    The function is for internal testing and evaluation of Digital power control. It has no functionality for the field, which is why there is no documentation.

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    Well that's not very helpful of them. At IWCE Aeroflex were touting their 3920 Series Digital with DMR software for MotoTRBO, one feature of which shows the "power profile of burst and of burst ramp up/ramp down".
    It is a fine thing to be honest, but it is also very important to be right

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    The service procedure doesn't even call for a digital service monitor, so anything else that comes with having one is a bit of a bonus.

    Very helpful if you're building DMR equipment though.

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    Just to be fair, the Moto rep who passed along the response was relaying it from Engineering. He was not purposely being unhelpful.

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    The answer works for me. Wondered what is was, was advised by a few and got what I was looking for.

    Cheers all!

    (Thanks for the direct Moto inquiry Mars)
    Last edited by p25smartzone; Apr 02, 2013 at 03:46 PM. Reason: Added a PS to the post.