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Roaming must be enabled by the ROAM option
switch, ROAMING menu parameter, or program-
ming (if the option switch and menu parameter are
not available).
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Scanning does not need to be enabled. However, if
system scanning is enabled, an LTR-Net system
must be selected. If an LTR or conventional system
is selected, roaming is disabled.
When roaming is enabled or disabled by the
option switch, either "ROAM ON" or "ROAM OFF"
is momentarily displayed to indicate the current mode.
With the menu mode, either "ON" or "OFF" is
selected as described in Section 2.6.2. If communica-
tion is to be maintained on the current locality regard-
less of signal strength, turn roaming off.
Registering on a New Locality
When power is turned on with roaming enabled,
registration is attempted on the currently selected
locality every 5 seconds if there is a free channel. The
registration message includes the mobile's unique ID
and the home repeater to be used. The registration
information is forwarded to the System and Subscriber
Manager which then knows its location.
If roaming was disabled when power was turned
on and then later enabled, registration on the current
system does not occur until a special event such as
transmitting, changing systems, or receiving a call
occurs. Therefore, the user may want to briefly press
the PTT switch after turning roaming on.
If the signal from a locality becomes weak (see
"Dropout and Capture Parameters" which follows) or
if two consecutive unsuccessful access attempts occur
("NO ACCES" displayed), the transceiver begins
automatic locality search. The unsuccessful access
counter is reset whenever power is cycled, the selected
system is changed, or a successful access occurs.
During locality search, the status channels of
other LTR-Net localities in the system scan list are
checked (see Section 2.7.6). During the first pass,
"HSQ SRCH" (High Squelch Search) is displayed, the
locality that was just dropped is not checked, and the
Tight Squelch setting programmed for each locality is
used (see "Dropout and Capture Parameters" which
follows).
If no localities are found on the first pass that
have a high enough signal level, the locality that was
just dropped is added back into the search list and all
localities in the scan list are checked using the Capture
setting programmed for each locality. The display
indicates "LCL SRCH", and searching continues until
a strong enough locality is found. If none are found
before the PTT switch is pressed again, the transmis-
sion is attempted on the last registered locality, and
searching resumes when the transmission ends.
De-Registering
If an LTR-Net system is selected when power is
turned off, a de-registration message is automatically
sent that tells the system that the mobile is no longer in
service. This increases system efficiency by reducing
the number of system resources used in trying to reach
out-of-service mobiles. Transceiver power is automati-
cally held on until this message is sent. If power to the
transceiver is switched off immediately, such as by a
relay, this message cannot be sent.
Revert System/Group Selection After Registration
After registration on a new locality occurs, "LCL
SRCH" is no longer displayed and the system of the
new LTR-Net locality is displayed. The new system is
the next higher system with a different locality that
could be accessed. For example, if System 3 was
selected and System 5 is the next higher system with a
different locality number, that becomes the selected
system if it can be accessed (wrap-around occurs after
the highest system is checked).
The selected group does not change when regis-
tration on a new site occurs. This allows registration
on a new locality to be nearly transparent to the user.
Therefore, when programming the transceiver, the
same group programming should be used in all LTR-
Net systems that a mobile roams into. If the same
group is not programmed in the new system, the last
selected group on the new system is selected. A call
can be received on the new locality before registration
occurs if the call is already active on the new locality.
Dropout and Capture Parameters
The transceiver squelch is used to control when
searching for a new site begins and also when registra-
tion on a new site occurs. A reference squelch level is
2-21
OPERATION
April 1999
Part No. 001-9800-600
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