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Thread: Mixed mode?

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    Default Mixed mode?

    For mixed mode, is the radio setup for DPL transmit and receive and NAC transmit and received on the same channel, or are two channels used? If on one channel, how does the repeater decide with mode to repeat?


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    If it's a computer, it just listens and says "hmm, this looks like IMBE vocoder modulated onto an FM signal following the P25 standard" or it says "hmm, this regular FM signal appears to have a PL tone modulated onto the carrier matching what someone told me to look for" and then retransmits it.

    You could probably build one with two receivers and a couple of or gates if you wanted.

    It's possible that was a little too sassy. Feel free to reprimand me.

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    As the question is about a repeater not an ASTRO 25 radio this thread was moved to Infrastructure - General
    Andrew

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    Hi Arlojanis,

    In terms of the Quantar, it uses only one channel. Like the ASTRO series radios, at all times, even in analog mode, the voice signal is digitized and handled internally as PCM data. The P25 frame sync detector is always active and running in parallel to the analog audio path, when it detects a valid frame sync, the repeater will switch to P25 mode. The frame sync is designed a certain way to have a specific amount of energy in it and DC bias etc, so that the CF4M detector is properly trained to the incoming transmission before the actual data begins to be sent.

    CTCSS and DPL are not required to key up a mixed mode repeater in analog, simple carrier squelch can be used, however I prefer to use a tone on all repeaters anyway.

    Cheers,
    Matt

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    Default Mixed mode?

    Quote Originally Posted by MattSR View Post
    CTCSS and DPL are not required to key up a mixed mode repeater in analog, simple carrier squelch can be used, however I prefer to use a tone on all repeaters anyway.

    Cheers,
    Matt
    I find a tone on the input makes a nice lid filter.
    Cyrus

    Bubbles: I'd like to see that Red Blue Green c***sucker put one of those together, duct-tapin' it.