BTSC TECHNIQUES
The disclosed BTSC encoder includes a left high pass filter means for receiving a digital left channel audio signal and for digitally high pass filtering the digital left channel audio signal and thereby generating a digital left filtered signal; a right high pass filter means for receiving a digital right channel audio signal and for digitally high pass filtering the digital right channel audio signal and thereby generating a digital right filtered signal; a matrix means for receiving the digital left and digital right filtered signals, and including means for summing the digital left and digital right filtered signals and thereby generating a digital sum signal, and including means for subtracting one of the digital left and digital right filtered signals from the other of the digital left and digital right filtered signals and thereby generating a digital difference signal; a difference channel processing means for digitally processing the digital difference signal; and a sum channel processing means for digitally processing the digital sum signal.
1 . A method of providing filter coefficients in a digital adaptive signal weighting system responsive in accordance with the BTSC standard, comprising:
calculating and electronically storing the filter coefficients; and
retrieving the filter coefficients for use in calculating the filter response of the digital adaptive signal weighting system such that its response in the digital domain is substantially equal to the corresponding analog frequency response specified by the BTSC standard.
2 . The method of providing filter coefficients according to claim 1 , further including using the filter coefficients to set the filter characteristics of a variable emphasis unit of the digital adaptive signal weighting system.
3 . The method of providing filter coefficients according to claim 2 , further including retrieving the filter coefficients for use according to the logarithm of the output signal of the digital adaptive weighting system.