Data compression apparatus and method for data recorder
First Claim
1. Apparatus for compression of a digital input information signal, comprising:
- input means for receiving a predetermined number n of input data samples representing said input information signal during a sampling period;
signal processing means responsive to said predetermined number n of input data samples for determining a compression parameter corresponding to the magnitude of an information parameter of said input information signal;
compression means responsive to said compression parameter for selecting a predetermined portion of said n input samples to provide a second predetermined number r of compressed data samples, where r is less than n;
output means for providing a compressed data string comprising said compression parameter and said predetermined number r compressed data samples;
means responsive to said r compressed data samples for obtaining a reconstructed input signal;
means for comparing said reconstructed input signal to said input information signal; and
means responsive to said comparing means for adjusting the number r so that said reconstructed input signal matches said input information signal within a predetermined error.
1 Assignment
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Accused Products
Abstract
A data compression method and apparatus particularly suitable for use in electrical power line fault data recorders. The system performs both gain compression and frequency compression. For gain compression, a predetermined number of samples are analyzed to determine a gain setting common to each sample in the set of samples. A reduced data string consisting of a gain code and data words having fewer bits than the input words are transmitted as a compressed data string. For frequency compression, a sample set representing the input signal is decimated until there remain only a sufficient number of data samples to satisfy the Nyquist criterion for the highest frequency component of interest. The frequency compressed output data string comprises a frequency code representing the highest frequency of interest followed by the set of decimated data samples.
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Citations
38 Claims
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1. Apparatus for compression of a digital input information signal, comprising:
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input means for receiving a predetermined number n of input data samples representing said input information signal during a sampling period; signal processing means responsive to said predetermined number n of input data samples for determining a compression parameter corresponding to the magnitude of an information parameter of said input information signal; compression means responsive to said compression parameter for selecting a predetermined portion of said n input samples to provide a second predetermined number r of compressed data samples, where r is less than n; output means for providing a compressed data string comprising said compression parameter and said predetermined number r compressed data samples; means responsive to said r compressed data samples for obtaining a reconstructed input signal; means for comparing said reconstructed input signal to said input information signal; and means responsive to said comparing means for adjusting the number r so that said reconstructed input signal matches said input information signal within a predetermined error. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of compressing a digital input information signal to reduce storage requirements, transmission bandwidth, or the like, comprising the steps of:
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(1) receiving a predetermined number n of input data samples representing said input information signal during a sampling period; (2) analyzing said predetermined number n of input data samples and determining a compression parameter corresponding to the magnitude of an information parameter of said input information signal; (3) selecting a predetermined portion of said data samples as a function of said compression parameter to provide a second predetermined number r of compressed data samples; (4) providing a compressed data string comprising said compression parameter and said predetermined number r compressed data samples; (5) obtaining a reconstructed input signal from said r compressed data samples; (6) comparing said reconstructed input signal to said input information signal; and (7) adjusting the number r in response to the comparing step so that said reconstructed input signal matches said input information signal within a predetermined error. - View Dependent Claims (28)
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12. Apparatus for compression of digital data, comprising:
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input means for receiving a predetermined number n of input data samples, each of said data samples comprising a data word having a predetermined number m of bits; signal processing means for analyzing said predetermined number n of input data samples and for determining a compression parameter corresponding to the magnitudes of said predetermined number n of input data samples; compression means responsive to said compression parameter for selecting a predetermined number k bits of each one of said data samples, where k is less than m, to provide said predetermined number n of k-bit compressed data samples; and output means for providing a compressed data stream comprising said compression parameter and said predetermined number of k-bit compressed data samples. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A method for compressing digital data to reduce storage requirements, transmission bandwidth, or the like, comprising the steps of:
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(a) receiving a predetermined number n of input data samples, each of said data samples comprising a data word having a predetermined number m of bits; (b) determining a compression parameter corresponding to the magnitude of said predetermined number n of input data samples; (c) selecting a predetermined number k bits of each one of said data samples, where k is less than m, corresponding to the magnitude of said compression parameter to provide said predetermined number n of k-bit compressed data samples; and (d) providing a compressed data stream comprising said compression parameter and said p redetermined number n of k-bit compressed data samples.
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19. Apparatus for compression of digital data, comprising:
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input means for receiving a predetermined number n of input data samples, each of said data samples comprising a data word having a predetermined number m of bits; first-in first-out memory means for storing said predetermined number n of input data samples and for sequentially recalling said input data samples; encoder means responsive to each one of said predetermined number n of input data samples and for providing a p-bit gain code corresponding to the magnitude of the largest one of said predetermined number n of input data samples; data selector means responsive to said gain code for selecting a predetermined number k bits of each one of said input data samples recalled from said first-in first-out memory means, where k is less than m, to provide said predetermined number n of k-bit compressed data samples; and output means for providing a compressed data string comprising said gain code and said predetermined number n of k-bit compressed data samples from said data selector means. - View Dependent Claims (20, 21, 22)
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23. A method of compressing a digital input information signal having a plurality of frequency components, comprising the steps of:
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(1) receiving a predetermined number n of input data samples representing said input information signal during a sampling period, said data samples having m bits; (2) determining a compression parameter corresponding to a preselected frequency component contained in said predetermined number n of input data samples in said input information signal; (3) selecting a second predetermined number r of data samples, where r is less than n, in response to said frequency compression parameter to provide said predetermined number r of compressed data samples; (4) determining a gain compression parameter corresponding to the magnitude of the amplitude of said input information signal during said sampling period; (5) selecting a predetermined number k bits of each one of said second predetermined number r of said data samples, where k is less than m, corresponding to said gain compression parameter; and (6) providing a compressed data string comprising said frequency compression parameter, said gain compression parameter, and said predetermined number r of k-bit compressed data samples. - View Dependent Claims (24, 25)
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26. Apparatus for compression of a digital input information signal, comprising:
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input means for receiving a predetermined number n of input data samples representing said input information signal during a sampling period, each of said data samples comprising a data word having a predetermined number m of bits; first signal processing means for analyzing said predetermined number n of input data samples and for determining a gain compression parameter corresponding to the magnitude of the amplitude of said input information signal during said sampling period; second signal processing means for analyzing said predetermined number n of input data samples and for determining a frequency compression parameter corresponding to a preselected frequency component contained in said input information signal during said sampling period; compression means responsive to said gain compression parameter and said frequency compression parameter for selecting a predetermined portion of said data samples to provide a second predetermined number r of compressed data samples; and output means for providing a compressed data string comprising said gain compression parameter, said frequency compression parameter, and said second predetermined number r compressed data samples. - View Dependent Claims (27)
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29. Apparatus for compression of an input information signal, comprising:
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input means for receiving a predetermined number n of input data samples representing said input information signal during a sampling period; signal processing means responsive to said predetermined number n of input data samples for determining a compression parameter corresponding to the magnitude of a frequency component of said input information signal, said compression parameter comprising a frequency compression parameter corresponding to the highest frequency of interest contained in said input information signal during said sampling period, said frequency compression parameter corresponding to a frequency component exceeding a predetermined threshold magnitude contained in said input information signal during said sampling period; compression means responsive to said compression parameter for selecting a predetermined portion of r data samples, where r is less than n, to provide a second predetermined number r of compressed data samples; output means for providing a compressed data string comprising said compression parameter and said predetermined number r compressed data samples; means responsive to said r compressed data samples for obtaining a reconstructed input signal; means for comparing said reconstructed input signal to said input information signal; and means responsive to said comparing means for adjusting the number r so that said reconstructed input signal matches said input information signal within a predetermined error. - View Dependent Claims (30)
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31. Apparatus for compression of an input information signal, comprising:
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input means for receiving a predetermined number n of input data samples representing said input information signal during a sampling period; signal processing means responsive to said predetermined number n of input data samples for determining a compression parameter corresponding to the magnitude of a frequency component of said input information signal, said compression parameter comprising a frequency compression parameter corresponding to the highest frequency of interest contained in said input information signal during said sampling period; compression means responsive to said compression parameter for selecting a predetermined portion of r data samples, where r is less than n, to provide a second predetermined number r of compressed data samples, said compression means being responsive to said frequency compression parameter for decimating said predetermined number n of data samples to obtain said predetermined number r of compressed data samples; output means for providing a compressed data string comprising said compression parameter and said predetermined number r compressed data samples; means responsive to said r compressed data samples for obtaining a reconstructed input signal; means for comparing said reconstructed input signal to said input information signal; and means responsive to said comparing means for adjusting the number r so that said reconstructed input signal matches said input information signal within a predetermined error.
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32. Apparatus for compression of an input information signal, comprising:
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input means for receiving a predetermined number n of input data samples representing said input information signal during a sampling period; signal processing means responsive to said predetermined number n of input data samples for determining a compression parameter corresponding to the magnitude of a frequency component of said input information signal, said compression parameter comprising a frequency compression parameter corresponding to the highest frequency of interest contained in said input information signal during said sampling period, said signal processing means comprising Fourier transform means for providing a plurality of frequency components corresponding to the frequency spectrum of said input information signal, means for comparing each of said plurality of frequency components to a predetermined value, and means for providing said compression parameter corresponding to the highest one of said plurality of frequency components which exceeds said predetermined value; compression means responsive to said compression parameter for selecting a predetermined portion of r data samples, where r is less than n, to provide a second predetermined number r of compressed data samples; output means for providing a compressed data string comprising said compression parameter and said predetermined number r compressed data samples; means responsive to said r compressed data samples for obtaining a reconstructed input signal; means for comparing said reconstructed input signal to said input information signal; and means responsive to said comparing means for adjusting the number r so that said reconstructed input signal matches said input information signal within a predetermined error. - View Dependent Claims (33, 34, 35)
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36. Apparatus for compression of an input information signal, comprising:
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input means for receiving said input information signal during a sampling period; analog-to-digital conversion means for converting said input information signal into said predetermined number n of input data samples; signal processing means responsive to said predetermined number n of input data samples for determining a compression parameter corresponding to the magnitude of an information parameter of said input information signal; compression means responsive to said compression parameter for selecting a predetermined portion of r data samples, where r is less than n, to provide a second predetermined number r of compressed data samples; output means for providing a compressed data string comprising said compression parameter and said predetermined number r compressed data samples; means responsive to said r compressed data samples for obtaining a reconstructed input signal; means for comparing said reconstructed input signal to said input information signal; and means responsive to said comparing means for adjusting the number r so that said reconstructed input signal said input information signal within a predetermined error.
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37. Apparatus for compression of digital data, comprising:
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input means for receiving a predetermined number n of input data samples, each of said data samples comprising a data word having a predetermined number m of bits; signal processing means for analyzing said predetermined number n of input data samples and for determining a gain compression parameter corresponding to the magnitudes of said predetermined number n of input data samples; compression means responsive to said gain compression parameter for selecting a predetermined number k bits of each one of said data samples, where k is less than m, to provide said predetermined number n of k-bit compressed data samples; and output means for providing a compressed data stream comprising said gain compression parameter and said predetermined number n of k-bit compressed data samples.
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38. Apparatus for compression of an input analog signal, comprising:
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input means for receiving a predetermined number n of input data samples, each of said data samples comprising a data word having a predetermined number m of bits; first-in first-out memory means for storing said predetermined number n of input data samples and for sequentially recalling said input data samples; encoder means responsive to each one of said predetermined number n of input data samples and for providing a p-bit gain code corresponding to the magnitude of the largest one of said predetermined number n of input data samples; data selector means responsive to said gain code for selecting a predetermined number k bits of each one of said input data samples recalled from said first-in first-out memory means, where k is less than m, to provide said predetermined number n of k-bit compressed data samples; and output means for providing a compressed data string comprising said gain code and said predetermined number n of k-bit compressed data samples from said data selector means, said output means comprising counter means responsive to count said predetermined number n of input data samples and to provide a period signal corresponding to the time represented by said predetermined number n of input data samples plus the time of said gain code.
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Specification