Adaptive-filter single-bit digital encoder and decoder and adaptation control circuit responsive to bit-stream loading

Claim 1

An adaptive single-bit digital encoder operating in a message frequency band for generating a digitally encoded output signal representative of and in response to an analog input signal and a clock sampling signal, said encoder comprising: digitizing means responsive to first and second analog signals and to said clock sampling signal for generating said digitally encoded output signal, wherein said output signal is a digital bit stream in which each single digital bit is responsive to a function of the first and second analog signals at each clock sampling signal sample time, means for coupling said analog electrical input signal to said digitizing means as said first analog signal, control signal generating means responsive to said digital bit stream for generating an adaptation control signal, adaptation means responsive to said digitally encoded output signal for dynamically dividing the message frequency band into first and second regimes of operation in response to said adaptation control signal, the adaptation means in the portion of the message frequency band subject to said first regime of operation acting on said digitally encoded output signal in the manner of delta-sigma modulation, and the adaptation means in the portion of the message frequency band subject to said second regime of operation acting on said digitally encoded output signal in the manner of delta modulation to produce an analog signal, and means for coupling the analog signal produced by the adaptation means to said digitizing means as said second analog signal.