Cable tester
First Claim
1. A cable tester that tests cable and that determines a cable status, comprising:
- a test module including;
a pretest state machine that senses activity on a first pair of said cable and enables testing if activity is not detected for a first period; and
a test state machine that is enabled by said pretest state machine, transmits a test pulse on said cable, measures a reflection amplitude and calculates a cable length, wherein said test module determines said status based on said measured amplitude and said calculated cable length, and wherein said pretest state machine enables testing of said first pair if, during said first period, activity is detected on said first pair and is subsequently not detected on said first pair for a second period after said activity is detected.
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Accused Products
Abstract
A cable testing system and method tests cable and determines status, cable length and reflection amplitude. The test module includes a pretest state machine that senses activity on the cable and enables testing if activity is not detected for a first period. A test state machine is enabled by the pretest state machine, transmits a test pulse on the cable, measures a reflection amplitude and calculates a cable length. The test module determines the status based on the measured amplitude and the calculated cable length. A lookup table includes a plurality of sets of reflection amplitudes as a function of cable length. The test module determines the status using the lookup table, the reflection amplitude and the cable length.
78 Citations
89 Claims
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1. A cable tester that tests cable and that determines a cable status, comprising:
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a test module including;
a pretest state machine that senses activity on a first pair of said cable and enables testing if activity is not detected for a first period; and
a test state machine that is enabled by said pretest state machine, transmits a test pulse on said cable, measures a reflection amplitude and calculates a cable length, wherein said test module determines said status based on said measured amplitude and said calculated cable length, and wherein said pretest state machine enables testing of said first pair if, during said first period, activity is detected on said first pair and is subsequently not detected on said first pair for a second period after said activity is detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A cable tester that tests cable and that determines a cable status, comprising:
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a test module including;
a pretest state machine that senses activity on said cable and enables testing if activity is not detected for a first period; and
a test state machine that is enabled by said pretest state machine, transmits a test pulse in said cable, measures a reflection amplitude and calculates a cable length, a lookup table that includes a plurality of sets of reflection amplitudes as a function of cable length, wherein said test module determines said status using said lookup table, said reflection amplitude and said cable length, wherein said test module determines said status based on said measured amplitude and said calculated cable length,and wherein said sets of reflection amplitudes define a plurality of windows including a first window that is defined by first and second thresholds, wherein said first threshold is based on a first set of reflection amplitudes that are measured as a function of cable length when a test cable type is an open circuit, and wherein said second threshold is based on a second set of reflection amplitudes that are measured as a function of cable length when said test cable type is terminated using a first impedance having a first impedance value. - View Dependent Claims (10, 11, 12)
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13. A cable tester that tests cable and that determines a cable status, comprising:
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a test module including;
a pretest state machine that senses activity on said cable and enables testing if activity is not detected for a first period; and
a test state machine that is enabled by said pretest state machine, transmits a test pulse on said cable, measures a reflection amplitude and calculates a cable length, wherein said test module determines said status based on said measured amplitude and said calculated cable length, wherein said test module transmits said test pulse, measures offset, subtracts said offset from said reflection amplitude, and detects peaks, and wherein if a second peak is not detected after a first peak and said reflection amplitude of said first peak is greater than a first threshold, said test module transmits a second test pulse having a second amplitude that is less than a first amplitude of said first test pulse. - View Dependent Claims (14, 15, 16, 17)
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18. A cable tester that tests cable and that determines a cable status, comprising:
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a test module including;
a pretest state machine that senses activity on said cable and enables testing if activity is not detected for a first period;
a test state machine that is enabled by said pretest state machine, transmits a test pulse on said cable, measures a reflection amplitude and calculates a cable length, wherein said test module determines said status based on said measured amplitude and said calculated cable length; and
an analog to digital converter (ADC) that measures said reflection amplitude, wherein said test module measures offset at said ADC, subtracts said offset from said reflection amplitude, and zeroes said reflection amplitude below a floor. - View Dependent Claims (19)
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20. A method of testing cable to determine a cable status, comprising:
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sensing activity on a first pair of said cable;
enabling testing on said first pair if said activity is not detected on said first pair for a first period;
transmitting a test pulse on said first pair of said cable;
measuring a reflection amplitude;
calculating a cable length; and
determining said cable status based on said measured amplitude and said calculated cable length, wherein said enabling step enables testing of said first pair if, during said first period, activity is detected on said first pair and is subsequently not detected on said first pair for a second period after said activity is detected. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
using a lookup table that includes a plurality of sets of reflection amplitudes as a function of cable length; and
determining said status using said lookup table, said reflection amplitude and said cable length.
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22. The method of claim 20 wherein said status includes open circuit and short status.
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23. The method of claim 20 further comprising displaying at least one of said status, said calculated cable length and said measured reflection amplitude.
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24. The method of claim 20 further comprising:
generating a test fail status when said cable is active for a period greater than a test fail period.
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25. The method of claim 20 further comprising implementing a cable tester in a network device.
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26. The method of claim 20 further comprising implementing a cable tester in a physical layer device.
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27. The method of claim 20 further comprising implementing a cable tester and a physical layer device in a single integrated circuit.
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28. A method of testing cable to determine a cable status, comprising:
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sensing activity on said cable;
enabling testing if said activity is not detected for a first period;
transmitting a test pulse on said cable;
measuring a reflection amplitude;
calculating a cable length;
determining said cable status based on said measured amplitude and said calculated cable length;
using a lookup table that includes a plurality of sets of reflection amplitudes as a function of cable length; and
determining said status using said lookup table, said reflection amplitude and said cable length, wherein said sets of reflection amplitudes define a plurality of windows including a first window that is defined by first and second thresholds, wherein said first threshold is based on a first set of reflection amplitudes that are measured as a function of cable length when a test cable type is an open circuit, and wherein said second threshold is based on a second set of reflection amplitudes that are measured as a function of cable length when said test cable type is terminated using a first impedance having a first impedance value. - View Dependent Claims (29, 30, 31)
declaring said cable an open circuit when said reflection amplitude is within said first window for said cable length;
declaring said cable a short circuit when said reflection amplitude is within said second window for said cable length; and
declaring said cable normal when said reflection amplitude is within said third window for said cable length.
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32. A method of testing cable to determine a cable status, comprising:
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sensing activity on said cable;
enabling testing if said activity is not detected for a first period;
transmitting a test pulse on said cable;
measuring a reflection amplitude;
calculating a cable length;
determining said cable status based on said measured amplitude and said calculated cable length;
measuring offset;
subtracting said offset from said reflection amplitude; and
detecting peaks, wherein if a second peak is not detected after a first peak and said reflection amplitude of said first peak is greater than a first threshold, said test module transmits a second test pulse having a second amplitude that is less than a first amplitude of said first test pulse. - View Dependent Claims (33, 34, 35, 36)
declaring a close open status if said reflection amplitude of a first peak after transmitting said second test pulse is greater than a second threshold; and
declaring an open status if said first peak is detected after a predetermined period after transmitting said second test pulse.
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34. The method of claim 33 further comprising:
declaring a perfectly terminated status if said first peak is not detected within said predetermined period after transmitting said second test pulse.
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35. The method of claim 34 further comprising canceling said test pulse when said cable transmits and receives on a common wire.
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36. The method of claim 32 wherein said second amplitude is approximately one-half of said first amplitude.
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37. A method of testing cable to determine a cable status, comprising:
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sensing activity on said cable;
enabling testing if said activity is not detected for a first period;
transmitting a test pulse on said cable;
measuring a reflection amplitude;
calculating a cable length;
determining said cable status based on said measured amplitude and said calculated cable length;
measuring said reflection amplitude;
measuring offset;
subtracting said offset from said reflection amplitude; and
setting said reflection amplitude below a floor equal to zero. - View Dependent Claims (38)
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39. A cable tester that tests cable and that determines a cable status, comprising:
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test module means for testing a first pair of said cable, wherein said test module means includes;
pretest means for sensing activity on said first pair of said cable and for enabling testing on said first pair if activity is not detected for a first period; and
test means that is enabled by said pretest means for transmitting a test pulse on said cable, for measuring a reflection amplitude and for calculating a cable length, wherein said test module means determines said status based on said measured amplitude and said calculated cable length, and wherein said pretest means enables testing on said first pair if, during said first period, activity is detected on said first pair and is subsequently not detected on said first pair for a second period after said activity is detected. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46)
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47. A cable tester that tests cable and that determines a cable status, comprising:
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test module means for testing said cable, wherein said test module means includes;
pretest means for sensing activity on said cable and for enabling testing if activity is not detected for a first period;
test means that is enabled by said pretest means for transmitting a test pulse on said cable, for measuring a reflection amplitude and for calculating a cable length, wherein said test module means determines said status based on said measured amplitude and said calculated cable length; and
a lookup means for storing a plurality of sets of reflection amplitudes as a function of cable length, wherein said test module means determines said status using said lookup means, said reflection amplitude and said cable length, wherein said sets of reflection amplitudes define a plurality of windows including a first window that is defined by first and second thresholds, wherein said first threshold is based on a first set of reflection amplitudes that are measured as a function of cable length when a test cable type is an open circuit, and wherein said second threshold is based on a second set of reflection amplitudes that are measured as a function of cable length when said test cable type is terminated using a first impedance having a first impedance value. - View Dependent Claims (48, 49, 50)
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51. A cable tester that tests cable and that determines a cable status, comprising:
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test module means for testing said cable, wherein said test module means includes;
pretest means for sensing activity on said cable and for enabling testing if activity is not detected for a first period; and
test means that is enabled by said pretest means for transmitting a test pulse on said cable, for measuring a reflection amplitude and for calculating a cable length, wherein said test module means determines said status based on said measured amplitude and said calculated cable length, and wherein said test module means transmits said test pulse, measures offset, subtracts said offset from said reflection amplitude, and detects peaks wherein if a second peak is not detected after a first peak and said reflection amplitude of said first peak is greater than a first threshold, said test module means transmits a second test pulse having a second amplitude that is less than a first amplitude of said first test pulse. - View Dependent Claims (52, 53, 54, 55)
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56. A cable tester that tests cable and that determines a cable status, comprising:
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test module means for testing said cable, wherein said test module means includes;
pretest means for sensing activity on said cable and for enabling testing if activity is not detected for a first period;
test means that is enabled by said pretest means for transmitting a test pulse on said cable, for measuring a reflection amplitude and for calculating a cable length, wherein said test module means determines said status based on said measured amplitude and said calculated cable length; and
an analog to digital converting means (ADC) for measuring said reflection amplitude, wherein said test module means measures offset at said ADC, subtracts said offset from said reflection amplitude, and zeroes said reflection amplitude below a floor. - View Dependent Claims (57)
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58. A network comprising:
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a first network device with a first physical layer;
a cable that includes a first pair and that communicates with said first physical layer;
a second network device with a second physical layer that communicates with said cable, wherein said first physical layer includes a cable tester that tests said first pair of said cable, that determines a cable status and that includes;
a test module including;
a pretest state machine that senses activity on said first pair of said cable and enables testing if activity is not detected on said first pair for a first period; and
a test state machine that is enabled by said pretest state machine, transmits a test pulse on said cable, measures a reflection amplitude and calculates a cable length, wherein said test module determines a cable status based on said measured amplitude and said calculated cable length, and wherein said pretest state machine enables testing on said first pair if, during said first period, activity is detected on said first pair and is subsequently not detected on said first pair for a second period after said activity is detected. - View Dependent Claims (59, 60, 61, 62)
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63. A network comprising:
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a first network device with a first physical layer;
a cable that communicates with said first physical layer;
a second network device with a second physical layer that communicates with said cable, wherein said first physical layer includes a cable tester that tests said cable, that determines a cable status and that includes;
a test module including;
a pretest state machine that senses activity on said cable and enables testing if activity is not detected for a first period;
a test state machine that is enabled by said Pretest state machine, transmits a test pulse on said cable, measures a reflection amplitude and calculates a cable length, wherein said test module determines a cable status based on said measured amplitude and said calculated cable length, a lookup table that includes a plurality of sets of reflection amplitudes as a function of cable length, wherein said test module determines said cable status using said lookup table, said reflection amplitude and said cable length, wherein said sets of reflection amplitudes define a plurality of windows including a first window that is defined by first and second thresholds, wherein said first threshold is based on a first set of reflection amplitudes that are measured as a function of cable length when a test cable type is an open circuit, and wherein said second threshold is based on a second set of reflection amplitudes that are measured as a function of cable length when said test cable type is terminated using a first impedance having a first impedance value. - View Dependent Claims (64, 65, 66)
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67. A network comprising:
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a first network device with a first physical layer;
a cable that communicates with said first physical layer;
a second network device with a second physical layer that communicates said cable, wherein said first physical layer includes a cable tester that tests said cable, that determines a cable status and that includes;
a test module including;
a pretest state machine that senses activity on said cable and enables testing if activity is not detected for a first period; and
a test state machine that is enabled by said pretest state machine, transmits a test pulse on said cable, measures a reflection amplitude and calculates a cable length, wherein said test module determines a cable status based on said measured amplitude and said calculated cable length, wherein said test module transmits said test pulse, measures offset, subtracts said offset from said reflection amplitude, and detects peaks, and wherein if a second peak is not detected after a first peak and said reflection amplitude of said first peak is greater than a first threshold, said test module transmits a second test pulse having a second amplitude that is less than a first amplitude of said first test pulse. - View Dependent Claims (68, 69, 70, 71)
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72. A network comprising:
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a first network device with a first physical layer;
a cable that communicates with said first physical layer;
a second network device with a second physical layer that communicates with said cable, wherein said first physical layer includes a cable tester that tests said cable, that determines a cable status and that includes;
a test module including;
a pretest state machine that senses activity on said cable and enables testing if activity is not detected for a first period;
a test state machine that is enabled by said pretest state machine, transmits a test pulse on said cable, measures a reflection amplitude and calculates a cable length, wherein said test module determines a cable status based on said measured amplitude and said calculated cable length; and
an analog to digital converter (ADC) that measures said reflection amplitude, wherein said test module measures offset at said ADC, subtracts said offset from said reflection amplitude, and zeroes said reflection amplitude below a floor. - View Dependent Claims (73)
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74. A network comprising:
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a first network device with a first physical layer;
a cable that communicates with said first physical layer;
a second network device with a second physical layer that communicates with said first physical layer over said cable, wherein said first physical layer includes a cable tester that tests a first pair of said cable, that determines a cable status and that includes;
test module means for testing said cable, wherein said test module means includes;
pretest means for sensing activity on said first pair of said cable and for enabling testing on said first pair if activity is not detected for a first period; and
test means that is enabled by said pretest means for transmitting a test pulse on said cable, for measuring a reflection amplitude and for calculating a cable length, wherein said test module means determines a cable status based on said measured amplitude and said calculated cable length, wherein said pretest means enables testing on said first pair if, during said first period, activity is detected on said first pair and is subsequently not detected on said first pair for a second period after said activity is detected. - View Dependent Claims (75, 76, 77)
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78. A network comprising:
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a first network device with a first physical layer;
a cable that communicates with said first physical layer;
a second network device with a second physical layer that communicates with said first physical layer over said cable, wherein said first physical layer includes a cable tester that tests said cable, that determines a cable status and that includes;
test module means for testing said cable, wherein said test module means includes;
pretest means for sensing activity on said cable and for enabling testing if activity is not detected for a first period;
test means that is enabled by said pretest means for transmitting a test pulse on said cable, for measuring a reflection amplitude and for calculating a cable length, wherein said test module means determines a cable status based on said measured amplitude and said calculated cable length; and
a lookup means for storing a plurality of sets of reflection amplitudes as a function of cable length, wherein said test module means determines said cable status using said lookup means, said reflection amplitude and said cable length, wherein said sets of reflection amplitudes define a plurality of windows including a first window that is defined by first and second thresholds, wherein said first threshold is based on a first set of reflection amplitudes that are measured as a function of cable length when a test cable type is an open circuit, and wherein said second threshold is based on a second set of reflection amplitudes that are measured as a function of cable length when said test cable type is terminated using a first impedance having a first impedance value. - View Dependent Claims (79, 80, 81)
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82. A network comprising:
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a first network device with a first physical layer;
a cable that communicates with said first physical layer;
a second network device with a second physical layer that communicates with said first physical layer over said cable, wherein said first physical layer includes a cable tester that tests said cable, that determines a cable status and that includes;
test module means for testing said cable, wherein said test module means includes;
pretest means for sensing activity on said cable and for enabling testing if activity is not detected for a first period;
test means that is enabled by said pretest means for transmitting a test pulse on said cable, for measuring a reflection amplitude and for calculating a cable length, wherein said test module means determines a cable status based on said measured amplitude and said calculated cable length; and
indicator means for displaying at least one of said status, said calculated cable length and said measured reflection amplitude.
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83. A network comprising:
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a first network device with a first physical layer;
a cable that communicates with said first physical layer;
a second network device with a second physical layer that communicates with said first physical layer over said cable, wherein said first physical layer includes a cable tester that tests said cable, that determines a cable status and that includes;
test module means for testing said cable, wherein said test module means includes;
pretest means for sensing activity on said cable and for enabling testing if activity is not detected for a first period; and
test means that is enabled by said pretest means for transmitting a test pulse on said cable, for measuring a reflection amplitude and for calculating a cable length, wherein said test module means determines a cable status based on said 5measured amplitude and said calculated cable length, wherein said test module means transmits said test pulse, measures offset, subtracts said offset from said reflection amplitude, and detects peaks, and wherein if a second peak is not detected after a first peak and said reflection amplitude of said first peak is greater than a first threshold, said test module means transmits a second test pulse having a second amplitude that is less than a first amplitude of said first test pulse. - View Dependent Claims (84, 85, 86, 87)
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88. A network comprising:
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a first network device with a first physical layer;
a cable that communicates with said first physical layer;
a second network device with a second physical layer that communicates with said first physical layer over said cable, wherein said first physical layer includes a cable tester that tests said cable, that determines a cable status and that includes;
test module means for testing said cable, wherein said test module means includes;
pretest means for sensing activity on said cable and for enabling testing if activity is not detected for a first period;
test means that is enabled by said pretest means for transmitting a test pulse on said cable, for measuring a reflection amplitude and for calculating a cable length, wherein said test module means determines a cable status based on said measured amplitude and said calculated cable length; and
an analog to digital converting means (ADC) for measuring said reflection amplitude, wherein said test module means measures offset at said ADC, subtracts said offset from said reflection amplitude, and zeroes said reflection amplitude below a floor. - View Dependent Claims (89)
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Specification