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US 4,674,122 AGranted
Encoding for the FMX companding system
AssigneeOrban Associates, Inc.
InventorRobert A. Orban
Life of this patent
Estimating the term…
Abstract
Improved FMX Companding apparatus for FM transmitter. A pilot subsystem which is substantially identical to the FMX audio path is used to develop a control signal which provides amplitude control through a VCA in the main FMX audio path.
Claims10
An FM stereophonic broadcasting system comprising:
- a first section for receiving L and R audio signals and for providing a first combined signal comprising L+R and a subcarrier modulated by L-R;
- a Q section for providing a second combined signal comprising
- said subcarrier shifted in phase and modulated by a compressed L-R signal, said compression being controlled by a first control signal;
- pilot subsystem comprising a pilot first section substantially similar to said first section coupled to receive said L and R audio signals and a pilot Q section substantially similar to said Q section for providing a third combined signal;
- filtering means for filtering said third combined signal to provide said first control signal for said compression in said Q section;
- and,
- delay means for delaying sald L and R audio signals coupled to said first section such that said audio signals are first received by said pilot subsystem, said delay means being coupled to said first section;
- whereby compression in said Q channel is achieved.
5 more elements
In a stereophonic FM braodcasting system which receives audio input signals and includes a first section having an L+R signal and a subcarrier signal modulated with an L-R signal, and a second section for compressing an L-R signal, an apparatus for providing improved compression for said second L-R signal comprising:
- a pilot subsystem comprising:
- (1) first voltage controlled amplifier (VCA) coupled to receive said L-R signal:
- (2) a first modulator for modulating said subcarrier signal with said L-R signal;
- (3) a second modulator for modulating said subcarrier shifted in phase with the output signal of said first VCA;
- (4) combining means for combining said L+R signal with the output of said first and second modulators;
- (5) a feedback path coupling the output of said combining means to said first VCA;
- (6) filtering means for filtering said output of said combining means to provide a control signal;
- a second VCA for providing said compression for said L-R signal in said second section, said second VCA coupled to receive said control signal;
- and,
- delaying means for delaying said audio input signals coupled to said first and second sections;
- whereby compression is provided.
8 more elements
Dependencies are inferred from the claim text.