Time domain reflectometer using successively delayed test pulses and an interleaved sampling procedure
First Claim
1. A time domain reflectometer for determining impulse characteristics of a line under test (LUT), comprising:
- a clock signal source;
start pulse means responsive to said clock signal source for applying a succession of test pulses during a succession of test periods to a line under test (LUT), each succeeding test pulse, after an initial test pulse, delayed in time in relation to a beginning of a test period by a test time increment that increases in each succeeding test period; and
reflection signal sample means coupled to said LUT, for sampling N reflection signals to obtain sampled reflection signal values, said reflection signal sample means operating to sample each said reflection signal n times per reflection signal, where n is an integer>
1, each sample occurring coherently with signals derived from said clock signal source, whereby each successive one of said N reflection signals is sampled n different positions that are different from sample positions of other of said N reflection signals as a result of said test time increment added to each succeeding test pulse.
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Abstract
A time domain reflectometer includes a clock signal source that synchronizes a Start pulse source which, in turn, generates a succession of Start pulses. Each succeeding Start pulse, after an initial Start pulse, is delayed in time from a preceding Start pulse by a test pulse interval plus a delay time. A test pulse circuit responds to each Start pulse by applying a test pulse to the LUT. A reflection signal sampling circuit samples N reflection signals in synchronism with the clock signal source, whereby successive ones of the N reflection signals are sampled at different delay times as a result of the delay time added to each succeeding Start pulse. A memory circuit assembles sampled reflection signal values from the N reflection signals in a manner that the reflection signal values are interleaved in time order as though all sampled reflection signal values were obtained from a single reflection signal.
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Citations
14 Claims
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1. A time domain reflectometer for determining impulse characteristics of a line under test (LUT), comprising:
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a clock signal source; start pulse means responsive to said clock signal source for applying a succession of test pulses during a succession of test periods to a line under test (LUT), each succeeding test pulse, after an initial test pulse, delayed in time in relation to a beginning of a test period by a test time increment that increases in each succeeding test period; and reflection signal sample means coupled to said LUT, for sampling N reflection signals to obtain sampled reflection signal values, said reflection signal sample means operating to sample each said reflection signal n times per reflection signal, where n is an integer>
1, each sample occurring coherently with signals derived from said clock signal source, whereby each successive one of said N reflection signals is sampled n different positions that are different from sample positions of other of said N reflection signals as a result of said test time increment added to each succeeding test pulse. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for time domain reflectometry comprising the steps of:
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a) applying a succession of test pulses over a succession of test periods to a line under test (LUT), each succeeding test pulse, after an initial test pulse, delayed in time from a beginning of a test period by a time that increases by a test time increment in each test period; b) sampling a plurality of reflection signals from said LUT to obtain sampled reflection signal values, each said sampling occurring at a fixed time in a sample period and further occurring at n predetermined times during each sample period for each reflection signal, where n is an integer>
1, successive ones of said plurality of reflection signals being sampled at different times during each sample period as a result of said test time increment added to each succeeding test pulse; andc) arranging sampled reflection signal values to represent a waveshape of said reflection signal. - View Dependent Claims (10, 11)
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12. A time domain reflectometer for determining impulse characteristics of a line under test, said reflectometer comprising:
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a test pulse signal source connected to the line under test to supply a plurality of test pulses to the line under test, each successive test pulse delayed in time from a preceding test pulse by a test period plus a time that increases by an increment of a test period, said increment increasing each test period; and means for sampling each reflected signal n times in each of a plurality of sample periods, wherein n is an integer>
1, each sampling occurring at a same preset time in each sample period. - View Dependent Claims (13, 14)
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Specification