Narrowband diagnostics for twisted pair wiring

An apparatus for diagnosing twisted pair wiring, comprising:

• a Subscriber Line Interface Circuit (SLIC) capable of transmitting an analog audio signal having a frequency less than or equal to 20 kHz onto the twisted pair wiring and capable of sensing current on the twisted pair wiring in response to the transmitted analog audio signal;
• a codec having a loopback mode of operation, the codec being capable of converting an input waveform comprised of digital audio data into the analog audio signal and of generating, from an analog signal corresponding to the sensed current, a digital output waveform comprised of delay samples and measurement data produced in response to the frequency;
• and
• a system processor capable of identifying where the measurement data appears in the digital output waveform by enabling the loopback mode, determining a sample delay from when a given sample is transmitted with the codec in the loopback mode of operation and when the system processor receives the given sample, and synchronizing the input waveform and the digital output waveform at a single analog/digital (A/D) sample using the sample delay, the system processor being further capable of determining, in response to identifying where the measurement data appears in the digital output waveform, electrical properties of the twisted pair wiring from the measurement data in the digital output waveform.

An apparatus for diagnosing twisted pair wiring, comprising:

• a codec having a loopback mode of operation, the codec being capable of converting digital audio data into a sinusoidal audio signal;
• a transmitter capable of sending the sinusoidal audio signal onto twisted pair wiring;
• a receiver capable of generating a sinusoidal output signal corresponding to current sensed in response to transmitting the sinusoidal audio signal over the twisted pair wiring;
• the codec further being capable of digitizing the sinusoidal output signal corresponding to sensed current to produce a digital output signal comprised of delay samples followed by measurement data;
• and
• a processor capable of identifying where the measurement data appears in the digital output signal by enabling the loopback mode, determining a sample delay from when a given sample is transmitted with the codec in the loopback mode of operation and when the processor receives the given sample, and synchronizing the input waveform and the digital output waveform at a single analog/digital (A/D) sample using the sample delay, the processor being further capable of determining, in response to identifying where the measurement data appears in the digital output signal, resistance and capacitance of the twisted pair wiring based on the measurement data in the digital output signal.