Claims
- 1. A method for performing time domain reflectometry on a communication
channel comprising: generating a sequence signal; preprocessing the sequence signal to counter effects of pre-transmission processing, the preprocessing creating a preprocessed sequence signal; transmitting the sequence signal over a communication channel; receiving a reflection signal from the communication channel in response to the transmitting the sequence signal; post-processing the reflection signal to counter the affects of post-reception processing that occurs after receiving the reflection signal; correlating the reflection signal with the sequence signal to generate a correlated signal; retrieving a template signal; aligning the template signal and the correlated signal to determine a point of alignment; subtracting the template signal from the correlated signal to remove near-end echo from the correlated signal; measuring a time interval between the point of alignment and a subsequent peak in the correlated signal; and multiplying the time interval by the rate of propagation of the sequence signal through the communication channel to obtain distance information regarding a line anomaly.
- 2. The method of claim 1, wherein the effects of pre-transmission processing transforms the preprocessed sequence signal into the sequence signal.
- 3. The method of claim 1, wherein the template signal is a correlated version of a reflection created by a line interface.
- 4. The method of claim 1, wherein the sequence signal comprises a maximal length sequence signal.
- 5. The method of claim 1, wherein the communication channel comprises a twisted pair conductor.
- 6. The method of claim 1, wherein the preprocessing comprises DMT demodulation and post-processing comprises DMT modulation.
- 7. The method of claim 1, further comprising performing a circular rotation of the sequence signal to create a rotated sequence signal;
transmitting the rotated sequence signal over the communication channel; receiving a rotated reflection signal; correlating the rotated reflection signal with the rotated sequence signal to create a rotated correlated signal; aligning the rotated correlated signal with the correlated signal; and adding the rotated correlated signal to the correlated signal to reduce or remove correlation artifacts on the correlated signal.
- 8. A method of processing a sequence signal and a reflection signal to counter the effects of one or more aspects of communication device processing comprising:
providing a sequence signal to a pre-processing module; preprocessing the sequence signal to create a modified sequence signal, the modified sequence signal constructed to yield the sequence signal after one or more forms of communication device processing; receiving a processed reflection sequence signal, the processed reflection sequence signal comprising a reflection of the sequence signal received over a line that was altered by one or more forms of communication device processing; and post-processing the processed reflection sequence signal to yield the reflection of the sequence signal.
- 9. The method of claim 8, wherein preprocessing comprises performing DMT demodulation and post-processing comprises performing DMT modulation.
- 10. The method of claim 8, wherein providing a sequence signal to a pre-processing module comprises generating an M-sequence signal and providing the M-sequence signal to the pre-processing module.
- 11. The method of claim 8, wherein the communication device that performs communication device processing comprises an asynchronous digital subscriber line communication device.
- 12. A system for performing sequence signal time domain reflectometry comprising:
a sequence generator configured to generate a sequence signal; a preprocessing module configured to process the sequence signal to thereby generate a processed sequence signal; a communication system transmitter configured to receive the processed sequence signal and negate the effects of the preprocessing module and transmit the sequence signal over a communication line; a communication system receiver configured to receive and modify a reflection signal received over the communication line; a postprocessing module configured to reverse the modifying effects of the communication system receiver to thereby generate the reflection signal; and a reflection signal analysis module configured to analyze the reflection signal.
- 13. The system of claim 12, further comprising a correlator configured to receive the reflection signal from the post-processing module.
- 14. The system of claim 12, wherein the communication system operates based on asynchronous digital subscriber line technology, the preprocessor performs at least DMT demodulation and the post-processor performs at least DMT modulation.
- 15. The system of claim 12, wherein the sequence generator is configured to generate one or more M-sequences.
- 16. A system for use in conjunction with a communication device for locating a line anomaly wherein the communication device comprises a transmitter configured to perform transmit processing and a receiver configured to perform receive processing, the system comprising:
a first processing module configured to:
receive a sequence signal; modify the sequence signal to thereby generate a modified sequence signal, wherein the modified sequence signal is configured to result in the sequence signal after transmit processing; and output the modified sequence signal to the transmitter; a second processing module configured to:
receive from the receiver a processed reflection signal subjected to receive processing by the receiver, wherein the receiver receives and processes the reflection signal to create the processed reflection signal; manipulate the processed reflection signal to recreate the reflection signal; and output the reflection signal; a reflection signal analysis module configured to receive the reflection signal from the second processing module and analyze the reflection signal to determine the location of one or more line anomalies.
- 17. The system of claim 16, wherein the communication device comprises a ADSL communication device.
- 18. The system of claim 16, wherein the first processing module and the sequence generator to generate a signal that will result in a sequence if transmitted by the transmitter.
- 19. The system of claim 16, wherein the reflection signal analysis module comprises a correlator.
- 20. The system of claim 16, wherein the reflection signal is generated when the sequence signal encounters a line anomaly as the sequence signal travels through a transmission line connected to the communication device.
- 21. A system for modifying a sequence signal to counter the effects of a communication device, the system comprising:
means for receiving a sequence signal; means for demodulating the sequence signal, the demodulation configured to counter a pre-transmission effect of a communication device transmitter; and means for providing an output from the means for demodulating to the communication device transmitter.
- 22. The system of claim 21, further comprising:
means for receiving a demodulated reflection signal from a receiver of the communication device, the reflection signal generated by transmission of a sequence signal over a transmission line; means for modulating the demodulated reflection signal to thereby counter the effects of the demodulation and restore the reflection signal; and means for processing the reflection signal.
- 23. The system of claim 22, wherein the means for processing comprises a correlator.
- 24. The system of claim 21, further comprising means for generating a sequence signal connected to the means for receiving a sequence signal.
- 25. The system of claim 22, wherein the means for demodulating comprise a dual tone multi-frequency demodulator and the means for modulating comprises a dual tone multi-frequency modulator.
- 26. A method for performing time domain reflectometry on a communication channel comprising:
generating an sequence signal, the sequence signal having a sampling rate with a first phase associated therewith; transmitting the sequence signal over a communication channel; receiving a reflection signal from the communication channel in response to the transmitting of the sequence signal; sampling the reflection signal at a sampling rate having a second phase; correlating the reflection signal with the sequence signal to generate a correlated signal; repeating the steps of sampling and correlating one or more additional times to generate correlated signals, wherein during the one or more additional times the second phase is offset from the first phase; and selecting a point correlation with the largest amplitude from a correlated signal to calculate distance information.
- 27. The method of claim 26, further comprising:
retrieving a template signal; aligning the template signal and a correlated signal to determine a point of alignment; subtracting the template signal from the correlated signal to remove near-end echo from the correlated signal; measuring a time interval between the point of alignment and a subsequent peak in the correlated signal; multiplying the time interval by the rate of propagation of the sequence signal through the communication channel to obtain distance information regarding a line anomaly.
- 28. The method of claim 27, wherein the template signal is a correlated version of a reflection created by a line interface.
- 29. The method of claim 26, wherein a varying offset is introduced into the second phase at each of the repeating the steps one or more additional times.
- 30. The method of claim 26, wherein the communication channel comprises a twisted pair conductor.
- 31. The method of claim 26, further comprising performing a circular rotation of the sequence signal to create a rotated sequence signal;
transmitting the rotated sequence signal over the communication channel; receiving a rotated reflection signal; correlating the rotated reflection signal with the rotated sequence signal to create a rotated correlated signal; aligning the rotated correlated signal with the correlated signal; and adding the rotated correlated signal to the correlated signal to reduce or remove correlation artifacts on the correlated signal.
- 32. A method for increasing the accuracy of a time domain reflectometry operation based on sequence signal analysis, the method comprising:
generating one or more sequence signals; transmitting the one or more sequence signals over a transmission line; receiving a reflection signal; sampling the reflection signal at a first phase to create a first sampled signal; correlating the first sampled signal to create a first correlated signal; sampling the reflection signal at a second phase, the second phase being offset from the first phase, to create a second sampled signal; correlating the second sampled signal to create a second correlated signal; and analyzing one or more points of correlation of the first correlated signal and the second correlated signal to determine a point of correlation with the greatest magnitude.
- 33. The method of claim 32, further comprising calculating a distance to a line anomaly based on the point of correlation with the greatest magnitude.
- 34. The method of claim 32, wherein at least one of the one or more sequence signals comprises an M-sequence.
- 35. The method of claim 32, wherein the correlation is cross-correlation.
- 36. The method of claim 32, wherein a first sequence signal is transmitted to create the first sampled signal and a second sequence signal is transmitted to create the second sampled signal.
- 37. A system for generating data, the data for use in locating a line anomaly, the system comprising:
a sequence source configured to provide a sequence signal; a digital to analog converter connected to receive the sequence signal and convert the sequence signal to analog waveform; a transmitter configured to transmit the sequence signal; a receiver configured to receive a reflection signal, the reflection signal comprising a reflection of the sequence signal; an analog to digital converter configured to convert the reflection signal to a digital format, the conversion controlled at lest part by a clock signal; a clock signal generator configured provide a clock signal to either or both of the digital to analog converter and the analog to digital converter; and a clock signal modifier configured to modify the clock signal provided to either or both of the digital to analog converter and the analog to digital converter.
- 38. The system of claim 37, wherein the clock signal modifier modifies the phase of the clock signal provided to the digital to analog converter or the analog to digital converter relative to an unmodified clock signal.
- 39. The system of claim 37, wherein the clock signal generator and the clock signal modifier comprise a phase lock loop.
- 40. The system of claim 37, wherein the clock signal modifier comprises an up-sampler, a variable delay, and a down-sampler.
- 41. The system of claim 37, wherein the sequence signal comprises an M-sequence.
- 42. The system of claim 37, wherein the receiver and the transmitter operate in accordance with a digital subscriber line protocol.
- 43. A system for increasing the resolution of a line probing operation, the system comprising one or more signal generation devices configured to, during two or more cycles of operation, provide an input to a transmit module sampler and an input to a receiver module sampler wherein during at least one cycle of operation the input to the transmit module sampler is out of phase with the input to the receive module sampler.
- 44. The system of claim 43, wherein a cycle of operation comprises a transmission of a sequence signal and receipt and processing of a reflection of the sequence signal.
- 45. The system of claim 43, wherein a line probe operation is configured to provide location information regarding a location of a line anomaly.
- 46. The system of claim 43, wherein the receive module sampler comprises an analog to digital converter and the transmit module sampler comprises a digital to analog converter.
- 47. The system of claim 43, wherein the receive module sampler comprises an analog to digital converter and a transmit module sampler comprises a digital to analog converter and the input comprise a clock signal.
- 48. The system of claim 43, wherein the signal generation device comprises an oscillator.
- 49. A system for locating a line anomaly in a transmission line comprising:
means for transmitting a sequence signal over the transmission line; means for receiving a reflection signal configured to receive a reflection signal created in response to transmission of a sequence over the line; means for sampling the reflection signal based on a signal with a first phase to create a first signal; means for sampling the reflection signal based on a signal with a second phase to create a second signal; and means for correlating the first signal and the second signal with the sequence signal to create one or more points of correlation; means for calculating a distance to a line anomaly based on the one or more points of correlation.
- 50. The system of claim 49, wherein a point of correlation with the largest magnitude is used to determine the location of the line anomaly.
- 51. The system of claim 49, wherein the first phase is different from the second phase.
Parent Case Info
[0001] The following application is a continuation-in-part of the U.S. patent application having Ser. No. 09/810,932, which was filed on Mar. 16, 2001.
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
09810932 |
Mar 2001 |
US |
Child |
10095847 |
Mar 2002 |
US |