LTR Standard systems have no dedicated control channel

Control channel

In radio communication, a control channel is a central channel that controls other constituent radios by handling data streams. It is most often used in the context of a trunked radio system, where the control channel sends data which coordinates users in talkgroups.In GSM networks, Control...

. All control data is sent as subaudible data along with voice transmissions. Systems can have any number of channels from 1 through a maximum of 20. Each channel in the system is assigned a unique number (01 through 20) and these need not be sequentially assigned. Each subscriber radio must be programmed with all channels in the system in proper logical channel order (the same requirement as EDACS

EDACS

EDACS stands for The Enhanced Digital Access Communication System, a radio communications protocol and product family invented in the General Electric Corporation in the mid 1980s.- History :...

 systems).

LTR Standard Talkgroups are written in the format A-HH-GGG.

• "A" is the area code and is either 0 or 1. The area code is the same for all Talkgroups in a given system and is arbitrarily chosen by the system operator; the most common use is to simply distinguish between Talkgroups on multiple systems.

• "HH" is the home repeater
  Repeater
  A repeater is an electronic device that receives asignal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances.-Description:...
  
   number and has twenty possible values, 01 through 20. Talkgroups usually use their home repeater
  Repeater
  A repeater is an electronic device that receives asignal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances.-Description:...
  
   by default, unless the repeater is already in use by other Talkgroups. If the home repeater is in use, the controller
  Controller (control theory)
  In control theory, a controller is a device which monitors and affects the operational conditions of a given dynamical system. The operational conditions are typically referred to as output variables of the system which can be affected by adjusting certain input variables...
  
   will assign another free repeater
  Repeater
  A repeater is an electronic device that receives asignal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances.-Description:...
  
   at random. If no repeater
  Repeater
  A repeater is an electronic device that receives asignal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances.-Description:...
  
  is free (all are in use), then the radio will receive a busy signal.

• "GGG" is the group number and has 254 possible values, 001 through 254.