US 7,254,374 B2Granted

Switchable multi-transmitter combiner and method

AssigneeSPX Corporation

InventorHenry Downs

Life of this patent

Estimating the term…

Loading patent…

Abstract

A transmitter-combining broadcast system and method is provided that allows IBOC-compatible broadcast with simple analog-to-IBOC upgradeability with high efficiency. At full power, a standard analog signal and an IBOC-compatible digital signal are transmitted by combining the output of a wide-band transmitter containing VHF-FM analog and in-band digital signals with the output of a second transmitter containing VHF-FM analog alone. By shifting signal phase, two analog signals can be combined with low loss, and net power waste can be reduced by at least 80%. The approach enables full IBOC upgradeability for existing analog-only systems, including reuse of existing transmitting equipment. Full IBOC compliance is supported, including during operation with reduced power. Switchover between partial and full power operating modes can be performed without full system shutdown.

Claims25

Dependent claims

A broadcast signal combiner, comprising:

a first transmitter having an output port, wherein said first transmitter is configured to output a broadcast-compatible first analog signal, to operate on a specified channel, and to have a first power level;
a second transmitter having an output port, wherein said second transmitter is configured to output a broadcast-compatible second analog signal on the specified channel and substantially synchronous with the first analog signal, having a second power level, and simultaneously output a broadcast-compatible digital signal having a third power level and conforming to In-Band On-Channel signal requirements that operates on the specified channel;
a broadcast signal coupler having at least a first and a second input port, and at least a first and a second output port, wherein said first coupler input port is in communication with said first transmitter output port, and said second coupler input port is in communication with said second transmitter output port;
a first phase shifter having at least an input port and an output port, wherein said first phase shifter input port is in communication with said broadcast signal coupler first output port;
a second phase shifter having at least an input port and an output port, wherein said second phase shifter input port is in communication with said broadcast signal coupler second output port;
a multiport combiner having at least a first and a second input port and at least a first and a second output port, wherein said multiport combiner first input port is in communication with said first phase shifter output port, and wherein said multiport combiner second input port is in communication with said second phase shifter output port;
and
a load coupled to said multiport combiner second output port.

5 more elements

A method for combining broadcast signals, comprising

generating a first broadcast signal having an analog component;
generating a second broadcast signal having an analog component and a digital component;
splitting the first broadcast signal into two generally equal parts, wherein the two parts each contain all of the signal content at generally half of the power, and wherein the two parts are in quadrature, with the first part leading the second part in phase;
splitting the second broadcast signal into two generally equal parts, wherein the two parts each contain all of the signal content at generally half of the power, wherein the two parts are in quadrature, with the first part leading the second part in phase, and wherein the first part is physically collocated with the second part of the first broadcast signal to form a first set, and the second part is physically collocated with the first part of the first broadcast signal to form a second set;
phase shifting at least one of the collocated sets of broadcast signal parts;
combining the sets of broadcast signal parts to form a combined broadcast signal;
and
sending an output of the combined broadcast signal into a non-radiating load, wherein the phase of the phase shifted broadcast signals results in less than 10 percent of the analog power of the first and second broadcast signals being sent to the non-radiating load.

5 more elements

Dependencies are inferred from the claim text.