LTR-Net Data Description

From The RadioReference Wiki

LTR-Net Field Values

Channel In Use (CHiU) Field

1 - 20 Standard LTR LCNs
17 Radio Unique ID (when Home = 24)
18 Site ID (when Home = 24)
24 Channel Transmit Frequency
25 Channel Receive Frequency
26 Neighbor Site ID
28 LCN Channel Map

Home Repeater Field

1 - 20 Standard LTR LCNs
24 Special - see CHiU
29 Directed Group Call
30 Hang Code, channel is in use, but mute audio
31 Turn Off (Call/Command end)

Free Channel Field

00 No Free Channels Available
1 - 20 Standard LTR LCNs
21 Standard LTR Group Call
31 LTR-Net Group Call

LTR-Net Special Call Talk Groups (240-255)

x-xx-240 - x-xx-247 = Token Group ID calls.  This is a temporary (token) group identifier that is
           assigned to the mobile for the duration of the call, when the mobile is making certain
           types of calls, like Auxiliary call, TELCO call, or Data call:
           x-xx-240 = Auxiliary Call
           x-xx-241 = Telephone to Mobile/Mobile to Telephone Call
x-xx-253 = Radio register - assign Unique ID/DONUT (Do Nothing) Call Group - used when
           the system is sending LTR-Net messages to a mobile and wants the channel to
           stay open, but doesn't want any of the mobiles to unsquelch their audio.
x-xx-254 = CWID Morse Code FCC Callsign Broadcast
x-xx-255 = Channel Idle

LTR-Net Radio Unique Identifiers

LTR assigns all radios to a group and when you call one radio, all radios in the group participate. LTR-Net allows calling to single radios by using the unique identifier assigned to each LTR-Net radio. Unique radio identifier messages can normally be found on traffic channels, because that's where the radio will be listening. Since mobile radios are not normally assigned to the Home Status Channel, you may not encounter any unique IDs there. The following is a LTR unique radio address message:

+ OSW: 0 17 24 003 10 1D  (Unique ID 106)

The last three bits of the 24 field combine with the bits from 003 and 10 fields to form a 16-bit value that is the radio unique identifier. This addressing message is normally preceded and followed with a group 253 start message and a group 253 end (31-253) message.