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Thread: APX7000 missing some MDC IDs

  1. #1
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    Default APX7000 missing some MDC IDs

    Hi all,

    I recently came into an APX7000 V / UHF R1 radio and have been comparing its performance against my XTS in UHF. One thing I've noticed recently is that in a side-by-side comparison with my XTS, the APX seems to be missing about 15-20% of MDC ID decodes for reasons I can't quite determine. On the local public safety system I've been monitoring, it seems that some IDs are more likely to be decoded consistently by both, whereas some other IDs frequently give the APX trouble (but not the XTS).


    On both radios MDC DOS is disabled, MDC coast time is set to zero so as to catch back-to-back IDs. Happy to post more info about the configuration of either radio if requested. Maybe I'm just missing something simple here?


  2. #2
    Neo No Longer Registered

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    Double check and make sure your bandwidth is set proper for the channel(s) your having problems decoding MDC. I know the APX is much pickier with decoding MDC, and if bandwidth is wrong, it makes the job that much more difficult decode properly.

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    Quote Originally Posted by Neo View Post
    Double check and make sure your bandwidth is set proper for the channel(s) your having problems decoding MDC. I know the APX is much pickier with decoding MDC, and if bandwidth is wrong, it makes the job that much more difficult decode properly.
    I'm pretty sure that I have the bandwidth set correctly for this system (if anything, I've erred on the wide side), but I will certainly check this. Also helpful to have the data point of someone else saying that the APX line is picky about MDC. I'm running R8 firmware currently, but didn't do a comparison test before upgrading so I can't say whether the recent firmware makes a difference or not.

    Something else that's interesting that I noticed during some further testing was that the APX seems to have particular trouble with specific IDs. There were at least two unit numbers that consistently did not decode with the APX, that the XTS got every time. Very strange.

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    Wirelessly posted (Droid 2 Global)

    I would bet either your apxs alignment is off, or the radio your monitoring is off. The apx line is very particluar on deviation settings.

  5. #5
    Neo No Longer Registered

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    I noticed the same thing, the xts5000 would decode a MDC, but the APX would not or missed many signatures. If the deviation is not correct in the APX will have a hard time decoding. I had a 50% decode rate with the wrong deviation settings. Once I corrected it, I now have 100% decode success.

    APX are WAY more picky when it comes to deviation and decoding MDC signatures.

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    Yeah, the Astro25 radio are less tolerant than a pro series or a cp series as well. Then the apx and trbo need the tightest tolerance. We have a bunch of PM1500's that will mute when they are on there narrowband fire dispatch channel and one of the neighboring towns who is still wide sets off Qc2 tones.

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    Might this have something to do with why QCII isn't available on APX radios? Maybe they can't get it to work reliably?
    Andrew

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    I put that one firmly in the column of "lazy ass programmer thinks its beneath him to add 30 year old tech to a state of the art radio" and a * of "The desgin team has there head up there ass far enough they can no longer here the customer feedback"

  9. #9
    syntrx No Longer Registered

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    Nah. Tone detection, especially for something like QC2 tones is as easy as **** from a software perspective. Motorola just doesn't feel like doing it.

    QC2 and 5-tone paging went away down this way about 25 years ago; it's been all POCSAG since then.