Method and apparatus for processing a wide dynamic range signal
AssigneePiRadian, Inc.
InventorsKamran Khorram Abadi, James T. Walker, Robert Gustav Lorenz
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Abstract
Method and apparatus are provided for processing a wide dynamic range analog signal which comprises a compressive nonlinear transfer function responsive to the average amplitude of the signal without feedback along the signal path. The invention employs frequency selective filtering and expansion of the compressed signal. The invention is applicable to any analog signal system having a plurality of channels carrying related signal information.
Claims26
An apparatus for processing an analog input signal, said analog input signal being subject to variations in amplitude, said apparatus comprising:
- a dynamic range compressor circuit with a circuit input and a circuit output coupled to receive said analog input signal for compressing the amplitude dynamic range of said analog input signal to obtain a compressed internal signal corresponding to said analog input signal at said circuit output;
- a detection circuit coupled to said circuit output of said dynamic range compressor circuit to produce a detected signal corresponding to amplitude of said compressed internal signal;
- a frequency-selective filtering means for filtering said detected signal to obtain an averaged control signal for a signal processing element;
- and
- a signal processing element responsive to said averaged control signal and operative on said circuit output of said dynamic range compressor circuit to expand the compressed internal signal to obtain an output signal representative of said analog input signal.
An apparatus for processing an analog input signal, said analog input signal being subject to variations in amplitude, said apparatus comprising:
- a dynamic range compressor circuit with a circuit input and a circuit output coupled to receive said analog input signal for compressing the amplitude dynamic range of said analog input signal at said circuit output;
- means for synchronous demodulation of said circuit output of said dynamic range compressor;
- a frequency-selective filtering means for filtering output of said synchronous demodulation means;
- a signal processing element responsive to output of said filtering means and operative on said circuit output of said dynamic range compressor circuit to expand the compressed internal signal to obtain an output signal representative of said analog input signal.
A method for processing analog input signals comprising:
- receiving said analog input signal;
- compressing the amplitude dynamic range of the analog input signal according to a nonlinear transfer function to obtain a compressed internal signal;
- filtering a quantity related to magnitude of the analog input signal according to frequency selective criteria to obtain a control signal;
- expanding the compressed internal signal according to the control signal to obtain a constant amplitude output signal;
- and
- outputting the constant amplitude output signal, wherein the output signal is not subjected to feedback along its signal path from input.
Dependencies are inferred from the claim text.