Method and apparatus for measuring the time delay between signals
First Claim
1. A signal processing system for measuring the time delay between first and second signals, said system comprising:
- means for receiving said first and second signals; and
means for comparing said first signal to said second signal to determine the time delay of said second signal relative to said first signal comprising;
means responsive to said first and second signals for dissecting them individually into respective first and second sets of components, each component having a power level, and a primary frequency range, each component in said first set having a different primary frequency range and having a corresponding component in said second set having the same primary frequency range;
means responsive to said corresponding components of said first and second sets for generating a weighted time delay of each component in said second set relative to its corresponding component in said first set; and
means for combining said weighted time delays to provide a measure of the time delay of said second signal relative to said first signal.
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Abstract
A system for determining the delay between first and second signals includes apparatus for characterizing each signal and apparatus responsive to corresponding portions of the first and second characterizations for providing an estimate of the delay of the second signal relative to the first. In a preferred embodiment the characterizer dissects the signal into a plurality of separate components each having a different frequency. A cross-characterizer determines the time delay between corresponding components of the two characterizations and derives a weight for each determined delay. A cross-characterization combiner forms a weighted sum of the determined component delays which becomes the discriminated delay between the two signals.
46 Citations
22 Claims
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1. A signal processing system for measuring the time delay between first and second signals, said system comprising:
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means for receiving said first and second signals; and means for comparing said first signal to said second signal to determine the time delay of said second signal relative to said first signal comprising; means responsive to said first and second signals for dissecting them individually into respective first and second sets of components, each component having a power level, and a primary frequency range, each component in said first set having a different primary frequency range and having a corresponding component in said second set having the same primary frequency range; means responsive to said corresponding components of said first and second sets for generating a weighted time delay of each component in said second set relative to its corresponding component in said first set; and means for combining said weighted time delays to provide a measure of the time delay of said second signal relative to said first signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of measuring the time delay between first and second signals which are susceptible to noise corruption, said method comprising the steps of:
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providing said first and second signals; and comparing said first and second signals to determine the time delay of said second signal relative to said first signal by; dissecting said first signal into H frequency components and said second signal into H corresponding components at the same frequencies; determining from corresponding first signal and second signal components i, for each integer value of i, i≦
i≦
H, both a time delay Δ
ti of said second signal component i relative to said first signal component i and an associated weight (Wi) for that delay, said associated weight Wi having a value which depends on the noise corruption of said components i; andcombining said determined time delays Δ
ti and their associated weights Wi to produce a weighted combination thereof as the value (Δ
t) of the measurement of the time delay of said second signal relative to said first signal, whereby said value Δ
t has a noise induced uncertainty which is less than it would be if said determined time delays Δ
ti were combined without weighting. - View Dependent Claims (11, 13, 14, 15, 16, 17, 18, 19, 21, 22)
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12. multiplying each of said time delays Δ
- ti by its associated weight Wi to provide individual weighted time delays Wi Δ
ti ;adding said individual weighted time delays together; adding said individual weights Wi together; dividing the sum of said weighted time delays by the sum of said weights; and providing the result of said division as the measured value (Δ
t) of said time delay of said second signal relative to said first signal.
- ti by its associated weight Wi to provide individual weighted time delays Wi Δ
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20. A method of measuring the time delay between first and second analog signals, said method comprising the steps of:
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receiving said first and second analog signals; and comparing said first analog signal to said second analog signal to determine said time delay between said first analog signal and said second analog signal by; sampling the amplitude of each of said analog signals at a rate commensurate with the bandwidth of said analog signals; converting the amplitudes of said samples to digital values, Fourier transforming a set of 2H samples from said first signal and a time related set of said samples from said second signal to provide first signal transform data and second signal transform data, respectively; extracting the first transform data phase (φ
1i) and power (S1i) and the second transform data phase (φ
2i) and power (S2i) for each frequency magnitude |fi | in said Fourier transform data;for each frequency magnitude determining a time delay ##EQU12## where the difference (φ
2i -φ
1i) is taken modulo 2π and
determining a delay weight ##EQU13## and generating from said delays Δ
ti and said weights Wi a measured value Δ
t of the time delay ##EQU14##
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Specification