| 摘要 |
<p>Subscriber line audio processing circuit apparatus comprising an analog-to-digital converter (16) coupled to a subscriber line for sampling an input audio signal at a first sampling frequency and for developing a series of digital words representing the amplitude of each sample, a first signal processor (18) for digitally filtering the series of digital words and for developing a first digitally processed signal having a second sampling frequency, a transmit register (20) for transmitting the first digitally processed signal to an external transmission line, a receiver register (22) for receiving a digital response signal at the second sampling frequency, a second signal processor (24) coupled to the receiver register for filtering the response signal and for developing a second digitally processed signal having a third frequency, a digital-to-analog converter (26) for converting the second processed signal to analog form suitable for output to the subscriber line, circuitry (44) and (66) coupling the first and second signal processor together and enabling the apparatus to match the input impedance of the subscriber line and to balance out components of the second processed signal coupled into first processed signal, and a control interface (32) for allowing the first and second signal processors to be digitally controlled from an external source. </p> |
