Glenayre Electronics, Inc.

Joel R Crowley-Dierks

Roger E Benz

David W Glessner

Mark L Witsaman

Glenn S Fawcett

A clock synchronization system for synchronizing the performance of a number of clocks (46) so that they run parallel with a reference clock is disclosed. Each clock of this synchronization system includes a counter (52) that indicates the current time and that is sequentially incremented by a counter advance signal applied thereto. A time counter controller (54) both initializes the counter and generates the clocking signal that controls the advancement of the counter. The time counter controller further monitors the time indicated by the counter and compares it to a reference-time signal received from a reference clock. Based on the comparison, the time counter controller selectively reinitializes the counter and adjusts the rate at which the clocking signal is applied to the counter so as to ensure that the counter advances at a rate equal to the rate at which the reference clock advances. In some versions of the invention, the comparison of the reference-time signal to the actual clock counter time is made at a maintenance operation point (58) remote from the clock. In these versions of the invention, the maintenance operation point reports the difference in the two times back to the time counter controller, which, in turn, makes the appropriate adjustments to the counter and to the clocking signal.

Apparatus for synchronizing a plurality of clocks in a simulcast network

A simulcast system for broadcasting the same signal for a number of spaced-apart broadcast sites is disclosed. The system (20) of this invention includes a hub (28) adapted to receive the signal to be simulcast and a number of stations (30) that actually broadcast the signal. The hub places the digital signal packets referred to as PDBs (36). As pan of the signal packetization process, the hub evaluates the rate at which the signals should be broadcast and assigns a start time at which the signals should be broadcast; this information is attached to the PDBs. After a PDB is created it is forwarded to the stations over a link channel. Each station includes a station controller (32) and a station transmitter (34). The station controller, upon receiving a PDB, forwards the signal therein to the transmitter at the start time indicated and at the appropriate broadcast rate. All of the stations transmitting the signals contained within a single PDB do so based on the start time and broadcast rate information contained in that PDB. Consequently, each station broadcasts the same signals at the same time and at the same rate so as to ensure their simultaneous transmission.

Digital simulcast transmission system

A simulcast system for broadcasting the same signal for a number of spaced-apart broadcast sites is disclosed. The system (20) of this invention includes a hub (28) adapted to receive the signal to be simulcast and a number of stations (30) that actually broadcast the signal. The hub places the digital signal packets referred to as PDBs (36). As part of the signal packetization process, the hub evaluates the rate at which the signals should be broadcast and assigns a start time at which the signals should be broadcast; this information is attached to the PDBs. After a PDB is created it is forwarded to the stations over a link channel. Each station includes a station controller (32) and a station transmitter (34). The station controller, upon receiving a PDB, forwards the signal therein to the transmitter at the start time indicated and at the appropriate broadcast rate. All of the stations transmitting the signals contained within a single PDB do so based on the start time and broadcast rate information contained in that PDB. Consequently, each station broadcasts the same signals at the same time and at the same rate so as to ensure their simultaneous transmission.

Growing community of inventors

Quincy, IL, United States of America

Joel R Crowley-Dierks