Method and system for data compression by variable frequency sampling

Claim 1

A system for translating an analog signal into a digital signal comprising series of digital data sets, comprising: means for sampling the analog signal at a first clocked sampling frequency and generating therefrom a series of digital samples; memory means for storing said digital samples; and control means for generating a sampling datum indicating a variable sampling frequency at a submultiple of said first sampling frequency as a function of an instantaneous frequency of said analog signal for selecting digital samples out of said memory means in response to said sampling datum, and forming said sampling datum and said selected digital samples into a data set; said control means comprising a microcomputer programmed to execute the following steps: (a) periodically reading each of the digital samples out of said memory means and counting the samples until a predetermined count value is reached; (b) detecting zero crossovers of said analog signal which occur during the interval between successive points at which said predetermined count is reached; (c) dividing said predetermined count value by the number of said detected zero crossovers to derive said sampling datum; (d) dividing said predetermined count value by said sampling datum to obtain a datum indicating the number of digital samples to be selected from said memory means; (e) reading said selected digital samples out of said memory means in response to said sampling datum; (f) forming said selected digital samples and said sampling datum into said data set; and (g) repeating the steps (a) to (f).

Claim 2

A system for translating an analog signal into a digital signal comprising series of digital data sets, comprising: means for sampling the analog signal at a first clocked sampling frequency and generating therefrom a series of digital samples; memory means for storing said digital samples; and control means for generating a sampling datum indicating a variable sampling frequency at a submultiple of said first sampling frequency as a function of an instantaneous frequency of said analog signal for selecting digital samples out of said memory means in response to said sampling datum, and forming said sampling datum and said selected digital samples into a data set; said control means comprising a microcomputer programmed to execute the following steps: (a) periodically reading each of the digital samples out of said memory means and counting the samples until a predetermined count value is reached; (b) detecting zero crossovers of said analog signal which occur during the interval between successive points at which said predetermined count is reached; (c) dividing said predetermined count value by the number of said detected zero crossovers to derive said sampling datum; (d) dividing said predetermined count value by said sampling datum to obtain a datum indicating the number of digital samples to be selected from said memory means; (e) reading said selected digital samples out of said memory means in response to said sampling datum; (f) forming said selected digital samples and said sampling datum into said data set; and (g) repeating the steps (a) to (f).

Claim 3

A system for translating an analog signal into a digital signal comprising series of digital data sets, comprising: means for sampling the analog signal at a first clocked sampling frequency and generating therefrom a series of digital samples; memory means for storing said digital samples; and control means for generating a sampling datum indicating a variable sampling frequency at a submultiple of said first sampling frequency as a function of an instantaneous frequency of said analog signal for selecting digital samples out of said memory means in response to said sampling datum, and forming said sampling datum and said selected digital samples into a data set; said means for performing the functions of: (a) periodically reading each of the digital samples out of said memory means and counting the samples until a predetermined sample count is reached; (b) deriving power spectrum data from said predetermined count of said digital samples; (c) detecting a highest order harmonic from said power spectrum data; (d) deriving said sampling datum as a function of the detected highest order harmonic; (e) successively reading the digital samples out of said memory means in response to said sampling datum; (f) forming said selected digital samples and said sampling datum into said data set; and (g) repeating the steps (a) to (f).

Claim 4

A system for translating an analog signal into a digital signal comprising series of digital data sets, comprising: means for sampling the analog signal at a first clocked sampling frequency and generating therefrom a series of digital samples; memory means for storing said digital samples; and control means for generating a sampling datum indicating a variable sampling frequency at a submultiple of said first sampling frequency as a function of an instantaneous frequency of said analog signal for selecting digital samples out of said memory means in response to said sampling datum, and forming said sampling datum and said selected digital samples into a data set; said means for performing the functions of: (a) periodically reading each of the digital samples out of said memory means and counting the samples until a predetermined sample count is reached; (b) deriving power spectrum data from said predetermined count of said digital samples; (c) detecting a highest order harmonic from said power spectrum data; (d) deriving said sampling datum as a function of the detected highest order harmonic; (e) successively reading the digital samples out of said memory means in response to said sampling datum; (f) forming said selected digital samples and said sampling datum into said data set; and (g) repeating the steps (a) to (f).

Claim 6

A system for translating an analog signal into a digital signal comprising series of digital data sets, comprising: means for sampling the analog signal at a first clocked sampling frequency and generating therefrom a series of digital samples; memory means for storing said digital samples; and control means for generating a sampling datum indicating a variable sampling frequency at a submultiple of said first sampling frequency as a function of an instantaneous frequency of said analog signal for selecting digital samples from said memory means, reading the selected digital samples out of said memory means in response to said sampling datum, and forming said sampling datum and said selected digital samples into a data set, further comprising second memory means and wherein said control means comprises a microcomputer programmed to execute the following steps: (a) successively reading said digital samples out of said memory means; (b) detecting a digital sample corresponding to a zero crossover of said analog signal and deriving a value indicated of the interval between successive zero crossovers; (c) dividing the interval indicative value by a predetermined number to derive an address code as said sampling datum to indicate the length of time from the detecting zero crossover; (d) addressing a said digital sample in response to said address code; (e) forming said data set of said address code and said addressed digital sample and storing the data set into second memory means; and (f) repeating the steps (a) to (e), further comprising: first and second digital-to-analog converters arranged to receive the digital sample and the sampling datum of each of said data set and to provide output analog signals representative thereof; a divider means for arithmetically dividing a difference between said successive analog outputs of said first digital-to-analog converter to generate an output slope signal; and an integrator means for integrating the output slope signal of said divider and generating an output signal for application to electroacoustic transducer means.

Claim 7

A system for translating an analog signal into a digital signal comprising series of digital data sets, comprising: means for sampling the analog signal at a first clocked sampling frequency and generating therefrom a series of digital samples; memory means for storing said digital samples; and control means for generating a sampling datum indicating a variable sampling frequency at a submultiple of said first sampling frequency as a function of an instantaneous frequency of said analog signal for selecting digital samples from said memory means, reading the selected digital samples out of said memory means in response to said sampling datum, and forming said sampling datum and said selected digital samples into a data set, further comprising second memory means and wherein said control means comprises a microcomputer programmed to execute the following steps: (a) successively reading said digital samples out of said memory means; (b) detecting a digital sample corresponding to a zero crossover of said analog signal and deriving a value indicated of the interval between successive zero crossovers; (c) dividing the interval indicative value by a predetermined number to derive an address code as said sampling datum to indicate the length of time from the detecting zero crossover; (d) addressing a said digital sample in response to said address code; (e) forming said data set of said address code and said addressed digital sample and storing the data set into second memory means; and (f) repeating the steps (a) to (e), further comprising: first and second digital-to-analog converters arranged to receive the digital sample and the sampling datum of each of said data set and to provide output analog signals representative thereof; a divider means for arithmetically dividing a difference between said successive analog outputs of said first digital-to-analog converter to generate an output slope signal; and an integrator means for integrating the output slope signal of said divider and generating an output signal for application to electroacoustic transducer means.

Claim 9

A system for translating an analog signal into a digital signal comprising series of digital data sets, comprising: means for sampling the analog signal at a first clocked sampling frequency and generating therefrom a series of digital samples; memory means for storing said digital samples; and control means for generating a sampling datum indicating a variable sampling frequency at a submultiple of said first sampling frequency as a function of an instantaneous frequency of said analog signal for selecting digital samples from said memory means, reading the selected digital samples out of said memory means in response to said sampling datum, and forming said sampling datum and said selected digital samples into a data set, further comprising second memory means and wherein said control means comprises a microcomputer programmed to execute the following steps: (a) successively reading said digital samples out of said memory means; (b) detecting a digital sample corresponding to a zero crossover of said analog signal and deriving a value indicated of the interval between successive zero crossovers; (c) dividing the interval indicative value by a predetermined number to derive an address code as said sampling datum to indicate the length of time from the detecting zero crossover; (d) addressing a said digital sample in response to said address code; (e) forming said data set of said address code and said addressed digital sample and storing the data set into second memory means; and (f) repeating the steps (a) to (e), wherein said microcomputer is programmed to execute the step of arithmetically dividing a difference between the digital values of successive digital samples by a digital value corresponding to the address code associated therewith to generate a digital signal representing the quotient of the division, further comprising: a digital-to-analog converter responsive to said quotient representing digital signal providing an analog output slope signal representative thereof; and means for integrating the output slope signal of said digital-to-analog converter to generate an output for application to an electroacoustical transducer means.

Claim 10

A system for translating an analog signal into a digital signal comprising series of digital data sets, comprising: means for sampling the analog signal at a first clocked sampling frequency and generating therefrom a series of digital samples; memory means for storing said digital samples; and control means for generating a sampling datum indicating a variable sampling frequency at a submultiple of said first sampling frequency as a function of an instantaneous frequency of said analog signal for selecting digital samples from said memory means, reading the selected digital samples out of said memory means in response to said sampling datum, and forming said sampling datum and said selected digital samples into a data set, further comprising second memory means and wherein said control means comprises a microcomputer programmed to execute the following steps: (a) successively reading said digital samples out of said memory means; (b) detecting a digital sample corresponding to a zero crossover of said analog signal and deriving a value indicated of the interval between successive zero crossovers; (c) dividing the interval indicative value by a predetermined number to derive an address code as said sampling datum to indicate the length of time from the detecting zero crossover; (d) addressing a said digital sample in response to said address code; (e) forming said data set of said address code and said addressed digital sample and storing the data set into second memory means; and (f) repeating the steps (a) to (e), wherein said microcomputer is programmed to execute the step of arithmetically dividing a difference between the digital values of successive digital samples by a digital value corresponding to the address code associated therewith to generate a digital signal representing the quotient of the division, further comprising: a digital-to-analog converter responsive to said quotient representing digital signal providing an analog output slope signal representative thereof; and means for integrating the output slope signal of said digital-to-analog converter to generate an output for application to an electroacoustical transducer means.

Claim 14

A method for translating an analog signal into a digital signal represented by a plurality of data sets, comprising: (a) sampling said analog signal at clock intervals to generate analog samples, converting the analog samples into digital samples and storing the digital samples into a memory; (b) sequentially addressing the stored digital samples, detecting successive digital samples corresponding to the analog samples at or near zero crosspoints of the original analog signal from the addressed digital samples and detecting the zero-crossing interval between the successive zero-crosspoint digital samples; (c) deriving an integral multiple of said clock interval from the detected zero-crossing interval and generating a sampling code identifying a sampling interval for representing said integral multiple; (d) retrieving the stored digital samples at said integral multiple of said clock intervals; and (e) forming the retrieved digital sample and said sampling code into a data set.

Claim 15

A method for translating an analog signal into a digital signal represented by a plurality of data sets, comprising: (a) sampling said analog signal at clock intervals to generate analog samples, converting the analog samples into digital samples and storing the digital samples into a memory; (b) sequentially addressing the stored digital samples, detecting successive digital samples corresponding to the analog samples at or near zero crosspoints of the original analog signal from the addressed digital samples and detecting the zero-crossing interval between the successive zero-crosspoint digital samples; (c) deriving an integral multiple of said clock interval from the detected zero-crossing interval and generating a sampling code identifying a sampling interval for representing said integral multiple; (d) retrieving the stored digital samples at said integral multiple of said clock intervals; and (e) forming the retrieved digital sample and said sampling code into a data set.

Claim 17

A method for translating an analog signal into a digital signal represented by a plurality of data sets, comprising: (a) sampling said analog signal at clock intervals to generate analog samples, converting the analog samples into digital samples and storing the digital samples into a memory; (b) sequentially addressing the stored digital samples, detecting successive digital samples corresponding to the analog samples at or near zero crosspoints of the original analog signal from the addressed digital samples and detecting the zero-crossing interval between the successive zero-crosspoint digital samples; (c) deriving an integral multiple of said clock interval from the detected zero-crossing interval and generating a sampling code identifying a sampling interval for representing said integral multiple; (d) retrieving the stored digital samples at said integral multiple of said clock intervals; and (e) forming the retrieved digital sample and said sampling code into a data set, further comprising: detecting a difference between the digital samples of the successive data sets; dividing said difference by the sampling code of the data set to generate a digital slope signal; converting the digital slope signal to an analog slope signal; and integrating said analog slope signal to generate a replica of the original analog signal.

Claim 18

A method for translating an analog signal into a digital signal represented by a plurality of data sets, comprising: (a) sampling said analog signal at clock intervals to generate analog samples, converting the analog samples into digital samples and storing the digital samples into a memory; (b) sequentially addressing the stored digital samples, detecting successive digital samples corresponding to the analog samples at or near zero crosspoints of the original analog signal from the addressed digital samples and detecting the zero-crossing interval between the successive zero-crosspoint digital samples; (c) deriving an integral multiple of said clock interval from the detected zero-crossing interval and generating a sampling code identifying a sampling interval for representing said integral multiple; (d) retrieving the stored digital samples at said integral multiple of said clock intervals; and (e) forming the retrieved digital sample and said sampling code into a data set, further comprising: detecting a difference between the digital samples of the successive data sets; dividing said difference by the sampling code of the data set to generate a digital slope signal; converting the digital slope signal to an analog slope signal; and integrating said analog slope signal to generate a replica of the original analog signal.

Claim 19

A method for translating an analog signal into a digital signal represented by a plurality of data sets, comprising: (a) sampling said analog signal at clock intervals to generate analog samples, converting the analog samples into digital samples and storing the digital samples into a memory; (b) sequentially addressing the stored digital samples, detecting successive digital samples corresponding to the analog samples at or near zero crosspoints of the original analog signal from the addressed digital samples and detecting the zero-crossing interval between the successive zero-crosspoint digital samples; (c) deriving an integral multiple of said clock interval from the detected zero-crossing interval and generating a sampling code identifying a sampling interval for representing said integral multiple; (d) retrieving the stored digital samples at said integral multiple of said clock intervals; and (e) forming the retrieved digital sample and said sampling code into a data set, further comprising: detecting a difference between the digital samples of the successive data sets; converting said digital difference to the difference of an analog quantity; converting the sampling code of the data set into an analog value; dividing the difference of analog quantity by said analog sampling value; and integrating the divided analog quantity to generate a replica of the original analog signal.

Claim 20

A method for translating an analog signal into a digital signal represented by a plurality of data sets, comprising: (a) sampling said analog signal at clock intervals to generate analog samples, converting the analog samples into digital samples and storing the digital samples into a memory; (b) sequentially addressing the stored digital samples, detecting successive digital samples corresponding to the analog samples at or near zero crosspoints of the original analog signal from the addressed digital samples and detecting the zero-crossing interval between the successive zero-crosspoint digital samples; (c) deriving an integral multiple of said clock interval from the detected zero-crossing interval and generating a sampling code identifying a sampling interval for representing said integral multiple; (d) retrieving the stored digital samples at said integral multiple of said clock intervals; and (e) forming the retrieved digital sample and said sampling code into a data set, further comprising: detecting a difference between the digital samples of the successive data sets; converting said digital difference to the difference of an analog quantity; converting the sampling code of the data set into an analog value; dividing the difference of analog quantity by said analog sampling value; and integrating the divided analog quantity to generate a replica of the original analog signal.

Claim 21

A method for translating an analog signal into a digital signal represented by a plurality of data sets, comprising: (a) sampling said analog signal at clock intervals to generate analog samples, converting the analog samples into digital samples and storing the digital samples into a memory; (b) periodically addressing a predetermined number of the stored digital samples, detecting the digital samples corresponding to the analog samples at or near zero crosspoints of the original analog signal from the addressed digital samples and counting the detected zero-crosspoint digital samples; (c) dividing said predetermined number by the count of said zero-crosspoint digital samples to derive an integral multiple of the clock intervals and generating a sampling code representing the integral multiple of the clock intervals; (d) dividing said predetermined number by said sampling code to determine the number of digital samples to be selected from among the addressed digital samples; (e) retrieving the digital samples at said integral multiple of the clock intervals from the memory; and (f) forming the retrieved digital sample and said sampling code into a data set.

Claim 22

A method for translating an analog signal into a digital signal represented by a plurality of data sets, comprising: (a) sampling said analog signal at clock intervals to generate analog samples, converting the analog samples into digital samples and storing the digital samples into a memory; (b) periodically addressing a predetermined number of the stored digital samples, detecting the digital samples corresponding to the analog samples at or near zero crosspoints of the original analog signal from the addressed digital samples and counting the detected zero-crosspoint digital samples; (c) dividing said predetermined number by the count of said zero-crosspoint digital samples to derive an integral multiple of the clock intervals and generating a sampling code representing the integral multiple of the clock intervals; (d) dividing said predetermined number by said sampling code to determine the number of digital samples to be selected from among the addressed digital samples; (e) retrieving the digital samples at said integral multiple of the clock intervals from the memory; and (f) forming the retrieved digital sample and said sampling code into a data set.

Claim 27

A method for translating an analog signal into a digital signal represented by a plurality of data sets, comprising: (a) sampling said analog signal at clock intervals to generate analog samples, converting the analog samples into digital samples which include zero-crossing digital samples corresponding to the analog samples at or near zero crossings of said analog signal and storing the digital samples into a memory; (b) periodically addressing a predetermined number of the stored digital samples at constant intervals and deriving a power spectrum from the addressed digital samples; (c) detecting a highest order harmonic from said power spectrum; (d) deriving an integral multiple of said clock intervals from said highest order harmonic and generating a sampling code representing said integral multiple of the clock interval; (e) dividing said predetermined number by said integral multiple of the clock interval to determine the number of digital samples to be selected from among the addressed digital samples; (f) retrieving the stored digital samples at said integral multiple of the clock interval; and (g) forming said retrieved digital sample and said sampling interval into a data set.

Claim 28

A method for translating an analog signal into a digital signal represented by a plurality of data sets, comprising: (a) sampling said analog signal at clock intervals to generate analog samples, converting the analog samples into digital samples which include zero-crossing digital samples corresponding to the analog samples at or near zero crossings of said analog signal and storing the digital samples into a memory; (b) periodically addressing a predetermined number of the stored digital samples at constant intervals and deriving a power spectrum from the addressed digital samples; (c) detecting a highest order harmonic from said power spectrum; (d) deriving an integral multiple of said clock intervals from said highest order harmonic and generating a sampling code representing said integral multiple of the clock interval; (e) dividing said predetermined number by said integral multiple of the clock interval to determine the number of digital samples to be selected from among the addressed digital samples; (f) retrieving the stored digital samples at said integral multiple of the clock interval; and (g) forming said retrieved digital sample and said sampling interval into a data set.