Patent ID: 7277860

Claim:
A digital BTSC signal encoder for encoding first and second digital audio signals with adjustments to conform to the BTSC MTS standard, said encoder comprising: (A) an input matrix for receiving said first and second digital audio signals comprising an adder for summing said first and second digital audio signals to generate a digital sum signal, and a subtractor for subtracting the second digital audio signal from the first digital audio signal to generate a digital difference signal; (B) sum channel processor comprising a first digital filter for digitally processing said digital sum signal; and (C) difference channel processor comprising a second digital filter for digitally processing said digital difference signal, further comprising a spectral compressor and a spectral feedback loop for generating a spectral gain control signal that is used to generate a first control signal that is input to the spectral compressor and that is clamped so that the first control signal does not go below a minimum value; wherein the digital BTSC encoder operates at a sample rate that is at least substantially ten times the bandwidth of the first and second digital audio signals so that said digital filters in the sum channel processor and the difference channel processor substantially match BTSC analog filter transform functions in both magnitude and phase.