US 5,673,292 AGranted

AM-PSK system for broadcasting a composite analog and digital signal using adaptive M-ary PSK modulation

AssigneeNorthrop Grumman Corporation

InventorBarry W. Carlin

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Abstract

A radio-frequency broadcasting system and method for simultaneously broadcasting analog and digital signals in a standard AM broadcasting channel wherein the system includes: a transmitter for providing, and broadcasting, a composite signal containing an adaptively-modulated phase-shift-keyed digital signal with analog programming material modulated thereon; and a receiver for detecting the composite signal, extracting the analog audio signal and digital audio, or data, therefrom, and playing back the received audio programming. The adaptively-modulated phase-shift-keyed digital signal is responsive to the transmitted signal, dynamically increasing the digital data transmission rate as the transmitted signal power increases. Symbol states are generally arranged around concentric arcs, and adjacent symbol states are generally equidistant.

Claims30

Dependent claims

A radio-frequency broadcasting system comprising:

a. at least one transmitter having
i. first signalling means for providing an analog signal;
ii. second signalling means, responsive to the amplitude of said analog signal, for providing an adaptively-modulated phase-shift-keyed digital signal having a plurality of symbol states arranged in a plurality of concentric rings or circular arcs defining a constellation, with the mutual arcuate separation between said symbol states being substantially the same for all of the rings of arcs in the constellation for providing substantially constant data fidelity measured in terms of bit error rate within an AM frequency band;
iii. a modulator, connected to said first signalling means and said second signalling means, for amplitude modulating said adaptively-modulated phase-shift-keyed digital signal with said analog signal, said modulator producing a composite signal;
and
iv. transmission means, connected to said modulator, for broadcasting a transmission signal, said transmission signal being proportional to said composite signal;
and
b. at least one receiver having
i. reception means for detecting said transmission signal, said reception means producing a received signal proportional to said transmission signal, said received signal having said analog signal and said adaptively-modulated phase-shift-keyed digital signal encoded therein;
and
ii. signal recovery means, including a phase-shift-keyed demodulator connected to said reception means for recovering said adaptively-modulated phase-shift-keyed digital signal from said received signal, and a constellation ring or arc decoder for purging superfluous bits in the digital signal recovered by said demodulator.

8 more elements

A radio-frequency transmitter comprising:

a. first signalling means for providing an analog signal;
b. second signalling means, responsive to the amplitude of said analog signal, for providing at least one adaptively-modulated phase-shift-keyed digital signal having a plurality of symbol states arranged in a plurality of concentric rings or circular arcs defining a constellation, with the mutual arcuate separation between said symbol states being substantially the same for all of the rings or arcs in the constellation for providing substantially constant data fidelity measured in terms of bit error rate within an AM frequency range;
c. a modulator, connected to said first signalling means and said second signalling means, for modulating said analog signal on said at least one adaptively-modulated phase-shift-keyed digital signal, said modulator producing a composite signal;
and
d. transmission means connected to said modulator, for broadcasting a transmission signal, said transmission signal being proportional to said composite signal.

2 more elements

Dependencies are inferred from the claim text.