Logical Channel Number

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Logical Channel Number, or LCN, is primarly used to define frequencies in use on M/A-COM EDACS systems and LTR systems.

All EDACS systems have 25 real LCN channel frequencies, and then an additional six 'status' channels reserved for special messaging to radios and infrastructure. They are not actual frequencies, but they indicate a certain status message to the calling radio. The following in Etrunk format lists these special LCNs:

s  DOWNLINK,1a,ffff,0
s  RESERVED,1b,ffff,0
s  CONVERTc,1c,ffff,0
s  QUEUEDid,1d,ffff,0
s  SYS-BUSY,1e,ffff,0
s  DENIEDid,1f,ffff,0

CONVERTc is used to tell a radio who PTTs while there talkgroup is active, and sends them to listen to the talkgroup, giving them an error beep as well. QUEUEDid is where a calling radio will be placed if they are waiting for a next available voice channel or phone patch, etc. SYS-BUSY, means the system is busy, no channels available, and somebody is in the Queue. DENIEDid is if that radio ID is not allowed on the system for some reason.

Additional Info

  • As mentioned in the HP-1E LTR Analyze results Thread,
    • "LCN "31" is the turn off code (like the 134 Hz tone on DPL) that tells the radio the call has ended and to mute the squelch."