Direct Mode Operation (DMO) 2-19
September 2008
Chapter 2 - MTM800 Product Information Manual 6866537D87-F
❏ Also members of the Talk Group can gain more information about the situation by listen of
background noises
5.2 Emergency Private Call
Emergency Call can be provisioned to be a Half-Duplex or Full-Duplex private call. If Emergency
Call is provisioned as private call, when the user presses the emergency button/key, the terminal will
initiate a private call with emergency call priority to the provisioned address. No emergency alarm is
sent and there is no emergency mode; the emergency state (all user indication and rejection of other
services) ends as soon as the call ends.
6 Direct Mode Operation (DMO)
DMO enables a terminal to use the group call functionality to talk to other terminals without using a
network. The terminals must all be in DMO prior to the call set up and communication is possible
using DMO Supported Features.
6.1 DMO Mode
The user is able to switch between DMO and TMO via a predefined button on the terminal.
There is only the Group mode of operation available to the user.
All menu items are displayed, but some menu functionality are not be selectable.
The RSSI level is displayed when the terminal is receiving a call.
6.2 DMO Group Call
The user is able to initiate a DMO group call and participate as a listener of a DMO group call.
Up to 1024 DMO talkgroups can be programmed into the terminal, each of which has an associated
DMO frequency. It is possible to map groups between DMO and TMO such that when moving from
TMO to DMO or vice-versa the appropriate group is selected.
Calls initiated by the terminal will be to the selected group and only incoming calls to the selected
group and the open group (DMO Inter-MNI calls), on the selected frequency, will be joined by the
terminal.
Note: Talkgroup Scanning in DMO is not supported.
The terminal supports call initiation and acceptance of call change over, thus enabling the talking
user (DMO master) to change within the DMO group call.
The terminals support talking party ID and when received from the transmitting terminal in an
incoming group call transaction the ID will be displayed on receiving terminals.
A transmitting terminal will periodically send ‘late entry’ signals to enable other terminals to join the
group call.
6.3 DMO Private Call
Private Call in DMO (a.n.a. Direct Mode Individual Call) allows the user to dial a selected TETRA
terminal rather than currently selected talkgroup. Only MS to MS communication is supported.
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