Shared resource modulator-demodulator circuits for use with vestigial sideband signals

Apparatus for a repeater for vestigial sideband (VSB) digital signals comprising:

• first and second transceiver circuits, wherein the first transceiver circuit demodulates an incoming VSB modulated signal so as to produce a stream of digital output symbol decisions and the second transceiver circuit modulates said decisions so as to produce an output VSB modulated signal, each of said first and second transceivers comprising:
• a complex multi-function filter, commonly used during VSB modulation and VSB demodulation and responsive to both an input signal and a mode signal, to provide an output filtered signal, wherein the multi-function filter imparts a different pre-defined function to the input signal corresponding to a current state of the mode signal;
• the mode signal being either in a pre-defined first or second state signifying VSB demodulation or VSB modulation, respectively;
• wherein the filter, during VSB demodulation and in response to the first state of the mode signal, equalizes the input signal such that the output filtered signal is an equalized version of the input signal, and the filter, during VSB modulation and in response to the second state of the mode signal, imparts a pre-defined frequency response characteristic to the input signal such that the output filtered signal is a frequency compensated version of the input signal;
• and
• a first multiplexor, responsive to the mode signal, for selectively routing as the input signal to the complex multi-function filter either, during VSB demodulation, a complex Nyquist filtered VSB modulated signal or, during VSB modulation, Hilbert transformed modulated symbols.