Motorola Corporation

Allen H Hollingsworth

Paul J Cizek

Michael S Harris

Hang K Chan

Alan G Deutschle

Marcellus W Cassidy, Iii

A simulcast transmission system (150) is disclosed in which a primary (402), a first, and a second transmitter site (302) form a first communication loop (403). The first communication loop (403) has at least a first and a second audio path, each of which are associated with a path identification (ID). The first and the second path IDs are also associated with a set of transmission delay parameters which are stored (401) at both the first and the second transmitter sites. The primary transmitter site (402) detects a location of an inoperative communication link (409) within the first audio path, and switches from the first audio path to the second audio path, whereby the second audio path does not traverse the inoperative communication link. The primary transmitter site (402) then broadcasts (512) a path condition ID to the first and the second transmitter sites. The first and second transmitter sites then retrieve (514) the set of transmission delay parameters associated with the second audio path.

Simulcast transmission system having automatic audio equalization

A frequency agile transmitter antenna combiner is disclosed that allows combining multiple transmitter outputs onto a single antenna feed where the transmitters are operated at multiple frequencies. According to the invention, a method is disclosed and an apparatus is described for receiving a plurality of RF signal inputs where each input may contain any of a predetermined set of frequencies. The input frequency is then coupled to a frequency splitter that couples the input frequency to a dedicated combiner that tends to isolate the RF inputs from each other. The signal is then coupled to a combiner output, and ultimately to a single antenna feed line.

Frequency agile transmitter antenna combiner

A multiport radio frequency (RF) signal combiner is described for combining three or more RF signals for application to an antenna. The combiner includes an input port for each RF signal, an output port coupled to the antenna, and a tuning port coupled to a tuning transmission line. The input ports, output port and tuning port are connected to a terminating element. The tuning transmission line is terminated by a fixed or adjustable short-circuit impedance for substantially eliminating the capacitive discontinuity created by interconnecting the input ports. The RF signal combiner can be advantageously utilized in any radio system where it is necessary to multiplex the RF signals from three or more transmitters to a single antenna.

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Hoffman Estates, IL, United States of America

Allen H Hollingsworth