Coherent signal detector for AM-compatible digital audio broadcast waveform recovery
AssigneeUSA Digital Radio Partners, L.P.
InventorsMark J. Dapper, Barry W. Carlin, Michael J. Geile
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Abstract
A coherent signal detector for extracting analog and digital information from a received AM-compatible digital broadcast waveform is provided. The waveform can have an in-phase component and a quadrature component. The detector can include a down converter for shifting the in-phase and quadrature components in phase, frequency, or both, in response to a phase word, thereby providing a recovered in-phase output and a recovered quadrature output. The signal detector also includes an integration circuit for integrating a portion of the recovered quadrature output over a first preselected time interval, which can be one digital time frame.
Claims29
A coherent signal detector for extracting analog and digital information from a received broadcast waveform, said broadcast waveform having an in-phase component and a quadrature component, said coherent signal detector comprising:
- (a) a down converter for frequency shifting said in-phase component and said quadrature component from a first preselected frequency range to a second preselected frequency range, said down converter providing a recovered in-phase output and a recovered quadrature output, said down converter being responsive to a phase word, said recovered in-phase output having generally said analog information and said digital information therein, said recovered quadrature output having generally said digital information therein;
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- (b) an integration circuit connected to said down converter, said integration circuit for integrating a portion of said recovered quadrature output over a first preselected time interval producing said phase word thereby, said phase word for correcting at least one of a frequency and a phase of said in-phase component and said quadrature component.
A coherent signal detector for extracting analog and digital information from a received broadcast waveform, said broadcast waveform having an in-phase component and a quadrature component, said coherent signal detector comprising:
- (a) a first down converter for frequency shifting said in-phase component and said quadrature component from a first preselected frequency range to a second preselected frequency range, said first down converter providing a recovered in-phase output and a recovered quadrature output;
- (b) a second down converter operably connected to said first down converter, said second down converter receiving said recovered in-phase and quadrature outputs, said second down converter for at least one of frequency and phase shifting said recovered in-phase and quadrature outputs from a first preselected phase to a second preselected phase, said second down converter providing a converted in-phase output and a converted quadrature output, said second down converter being responsive to a phase word, said phase word for correcting at least one of a phase and a frequency of said recovered in-phase output and said recovered quadrature output;
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- (c) an integration circuit connected to said second down converter, said integration circuit for integrating a portion of said converted quadrature output over a first preselected time interval producing said phase word thereby.
Dependencies are inferred from the claim text.