Data rate compression device for cable television return path using bandpass puncturing

A device for use in a cable television return path, comprising:

• an analog-to-digital converter configured to convert an analog return signal to a first stream of digital samples at a first data rate;
• a bandpass interpolation filter configured to receive the first stream of digital samples and to substantially remove signals outside of a predetermined frequency band;
• up-sampling logic configured to up-sample outputs of the bandpass interpolation filter and to generate a second stream of digital samples at a second data rate, the second data rate being a predetermined integer multiple of a center frequency of the predetermined frequency band;
• puncturing logic configured to puncture the second stream of digital samples at a predetermined odd integer rate and to generate a third stream of digital samples at a third data rate that is lower than the first data rate;
• a serializer configured to convert the third stream of digital samples to a serial bit stream;
• and
• an optical transmitter driven by the serial bit stream to generate an optical signal for transmission in optical medium of the return path of the cable television system.

A signal decoder for use in a cable television return path and configured to receive a first stream of digital samples that is generated by a transmitter bandpass interpolation filter having predetermined filter coefficients and that is punctured at a predetermined rate, the signal decoder comprising:

• zero-insertion logic configured to insert zeros in the first stream of digital samples according to the predetermined rate to produce a second stream of digital samples;
• and
• a bandpass interpolation filter having the predetermined filter coefficients configured to filter the second stream to generate a third stream of digital samples;
• and
• up-sampling logic configured to up-sample the third stream of digital samples to form an output stream of digital samples at an output data rate higher than that of the first stream of digital samples.

A device for use in a cable television return path, comprising:

• an optical data receiver configured to receive an optical signal from an optical medium and to convert the optical signal to a serial bit stream;
• a deserializer configured to convert the serial bit stream into a first stream of digital samples each having a plurality of bits;
• zero-insertion logic configured to insert zeros in the first stream of digital samples according to a predetermined rate to produce a second stream of digital samples;
• and
• a bandpass interpolation filter having predetermined filter coefficients configured to filter the second stream to generate a third stream of digital samples;
• up-sampling logic configured to up-sample the third stream of digital samples to form an output stream of digital samples at an output data rate higher than that of the first stream of digital samples;
• and
• a digital-to-analog converter configured to convert the output stream of digital samples to an analog signal.

A method of transmitting analog return signals in a digital return path of a cable television system, the method comprising:

• converting an analog return signal to a first stream of digital samples at a first data rate;
• filtering the first stream of digital samples to substantially remove signals outside of a predetermined frequency band with a first digital filter having predetermined filter coefficients;
• up-sampling the filtered stream of digital samples to generate a second stream of digital samples at a second data rate, the second data rate being a predetermined multiple of a center frequency of a predetermined frequency band;
• puncturing the second stream of digital samples at a predetermined odd integer rate to generate a third stream of digital samples;
• converting the third stream of digital samples to an optical signal for transmission in the return path of the cable television system.