MMI Technical Resource
   Updated 23 March 2003 Technical Terms   

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  • Digital Channel Guard (DCG)
    General Electric trademark term. [See "Digital Coded Squelch (DCS)"]

    Digital Coded Squelch (DCS)
    Digital type of signalling used for receiver squelch control. Receivers are equipped with decoders and transmitters are equipped with encoders. When an equipped receiver hears the same sub-audible signalling put out by the transmitter it will open up the speaker so the user can hear the audio. The transmitter just sends the DCS audio along with the users voice.
    Synonyms: Digital Channel Guard (DCG), Digital Private Line (DPL)

    Digital Private Line (DPL)
    Motorola trademark term. [See "Digital Coded Squelch (DCS)"]

    Dropout Delay
    [See "Hang Time"]

    Duplex
    The ability to receive on one frequency and transmit on the other simultaneously. Usually the principle operation of repeaters.

    Half Duplex
    The mode of receiving on one frequency and transmitting on another frequency but not simultaneously.

    Hang Time
    This is the time in which a repeater transmitter remains on the air after the receiver has lost its signal.
    Synonyms: Dropout Delay

    Repeater
    A communications station that receives a signal from a mobile unit or other station and retransmits it simultaneously for greater range. Usually on a mountain, building or high tower.

    Simplex
    Direct communications, from mobile unit to mobile unit with no repeater in the path.

    Squelch
    This means to quiet a receiver or other audio source.

    Squelch Tail
    The burst of white noise that occurs when a signal drops out of a receiver.

    Talk Around
    Simplex operation on the output frequency of a repeater pair.
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