Patent ID: 7953233
Filing Date: 2011-05-31
Classification: H04R

Abstract:
1. An apparatus including a synchronous detection and calibration system for a close-talking differential microphone array (CTDMA), comprising: a plurality of input electrodes to convey a plurality of microphone signals each of which corresponds to a source audio signal having a plurality of frequencies; controllable amplifier circuitry coupled to said plurality of input electrodes and responsive to a plurality of amplifier control signals and said plurality of microphone signals by providing a plurality of selectively amplified signals at each of said plurality of frequencies; controllable filter circuitry coupled to said controllable amplifier circuitry and responsive to a plurality of filter control signals and said plurality of selectively amplified signals by providing a plurality of selectively filtered signals at each of said plurality of frequencies; signal combining circuitry coupled to said controllable filter circuitry and responsive to said plurality of selectively filtered signals by providing a combination signal at each of said plurality of frequencies, wherein said combination signal has a plurality of values each of which is related to a difference between corresponding ones of said plurality of selectively filtered signals; synchronous signal detection circuitry coupled to one of said plurality of input electrodes and said signal combining circuitry, and responsive to one of said plurality of microphone signals and said combination signal by providing an error signal indicative of respective ones of said plurality of combination signal values; and calibration circuitry coupled to said synchronous signal detection circuitry, said controllable amplifier circuitry and said controllable filter circuitry, and responsive to said error signal by providing said plurality of amplifier control signals and said plurality of filter control signals such that said error signal, for each of said plurality of frequencies, is indicative of a minimum difference between said corresponding ones of said plurality of selectively filtered signals.