Broadcom Corporation

Motorola Corporation

Ronald Crochiere

Alexander Garland MacInnis

David Chaohua Wu

Hoang Nhu

Russ Lambert

David B Cranfill

Arthur Gerald Herkert

Kesavarajan Kaliyaperumal

A system and method are disclosed for performing digital multi-channel decoding of a BTSC composite audio signal. Each subsequent stage of the digital multi-channel decoding process is performed at the lowest sampling rate that yields acceptable performance for that stage. Analog-to-digital conversion of the composite audio signal is performed first to generate a composite digital audio signal. After analog-to-digital conversion, all signal processing may be performed in the digital domain. The composite digital audio signal is digitally filtered to frequency compensate for variations caused by previous stages of processing, including IF demodulation. Digital channel demodulation and filtering are performed to isolate single channels of the composite digital audio signal such as SAP, L&#x2212;R, and L+R channels. SAP and L&#x2212;R channels are DBX decoded resulting in corresponding decoded signals using a unique combination of digital filters that are an efficient translation of a corresponding combination of analog filters.

System and method of performing digital multi-channel audio signal decoding

A method for dynamically controlling audio signal gain in a communication device starts with determining a level of an input audio signal. The level is then mapped against a table of predetermined corresponding gain targets to determine an appropriate gain target for that level. The gain targets are then applied to the audio signal, which is then output. The invention is particularly suited to speakerphone operation in a communication device, wherein the gain targets provide compression, expansion or limiting so that distant speakers can be heard clearly.

Dynamic gain control of audio in a communication device

A system and method are disclosed for performing digital multi-channel decoding of a BTSC composite audio signal. Analog-to-digital conversion is performed on a composite analog audio signal at a fast clock rate to generate a composite digital audio signal at a first sample rate. Digital frequency compensation is performed on the composite digital audio signal at the first sample rate to generate a compensated composite audio signal. Digital channel demodulation and filtering are performed on the compensated composite audio signal at the first sample rate to generate a first single channel audio signal at a second sample rate.

Growing community of inventors

San Diego, CA, United States of America

Ronald Crochiere