Telecommunications – Transmitter and receiver at separate stations – Plural transmitters or receivers
Reexamination Certificate
2000-07-18
2004-06-08
Gary, Erika (Department: 2682)
Telecommunications
Transmitter and receiver at separate stations
Plural transmitters or receivers
C455S450000, C455S433000, C455S520000, C455S509000, C455S511000, C455S519000, C455S426100, C455S426200
Reexamination Certificate
active
06748230
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to wide area communications systems. More particularly, the present invention relates to a method and apparatus for updating announcement group information within a wide area dispatch system.
In normal processing of a wide area trunked system, communication unit or radio (hereinafter referred to as a “subscriber unit”) receives the announcement group ID of its affiliated talkgroup upon performing talkgroup affiliation. However, if the talkgroup to announcement group database in a zone controller is not available for use, the announcement group information cannot be delivered to the subscriber unit. For example, the talkgroup to announcement group database is not available when the database has not been configured by the zone manager. When the database has not been configured, it is not possible for the database to provide information about the announcement group. As a result, when the subscriber unit affiliates to a talkgroup and the talkgroup does not have a preconfigured announcement group, the zone controller will respond to the subscriber unit with an unknown announcement group signal (for example, Null group ID=0). Alternatively, when a site cannot communicate with the zone controller, i.e., it is in site trunking, the zone controller cannot deliver information about the announcement group to the site. A subscriber unit, therefore, may receive an unknown announcement group signal. Both of these situations are problematic because the subscriber unit may not be able to participate in calls for the announcement group that it was intended to receive.
When the zone controller database is configured or the site recovers from site trunking, current systems do not notify the subscriber unit of the updated information about the announcement group. The subscriber unit, therefore, will not be aware of the updated announcement group and will not receive calls it was intended to receive. As a result, there is a need for a method and an apparatus that detects when a subscriber unit is operating with an unknown announcement group signal and in response thereto sends a signal updating the announcement group to the subscriber unit.
REFERENCES:
patent: 4972460 (1990-11-01), Sasuta
patent: 5564071 (1996-10-01), Liou et al.
patent: 5956647 (1999-09-01), McDonald et al.
McDonald Daniel J.
Murphy Helen Anne
Gary Erika
Hughes Terri S.
Motorola Inc.
Nguyen David
Santema Steven R.
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