Audio digital recording and playback system

• US 4,636,876 A
• Filed: 09/17/1984
• Issued: 01/13/1987
• Est. Priority Date: 04/19/1983
• Status: Expired due to Term

• Current Assignee: CompuSonics Corp.
• Original Assignee: CompuSonics Corp.
• Inventors: Schwartz, David M.
• Primary Examiner(s): Canney, Vincent P.
• Application Number:
  US06/651,111
• Time in Patent Office: 848 Days
• Field of Search: 381/51, 381/41, 360/32, 328/14
• US Class Current: 360/32
• CPC Class Codes: G11B 20/10 Digital recording or reproducing
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence

Abstract

A microcomputer system for converting an analog signal, such as an audio signal representative of sound into a digital form for storing in digital form in a highly condensed code and for reconstructing the analog signal from the coded digital form is disclosed. The system includes reductive analytic means where the original digital data stream is converted to a sequential series of frequency spectrograms, signal amplitude histograms and waveform code tables. Approximately 100 times less storage space than previously required for the storage of digitized audio signals of high fidelity quality is thereby obtained. Additive synthesis logic interprets the stored codes and recreates an output digital data stream for digital to analog conversion that is nearly identical to the original analog signal.

Claims

1. A microcomputer recording system for recording analog signals in digital data form comprising:

converting means for converting an analog signal into at least three digital data streams, wherein the first of said digital data streams is a reference signal representative of the amplitude of a preselected range of frequencies in a relatively broad band width, and wherein the second of said data streams is produced by filtering the analog signal to produce a data stream indicative of a plurality of discrete frequencies encompassed by the bandwidth represented by said first data stream; and

wherein the third of said digital data streams is a reference signal representative of the amplitude of the analog signal for each of said plurality of discrete frequencies;

sampling means for producing a sequential stream of digital data samples in each of said digital data streams,

selection means for selecting a predetermined portion of the digital data samples produced by said sampling means in each digital data stream;

means for separately storing each of said predetermined portions of said digital data samples;

means for comparing said predetermined portion of said first reference data stream containing amplitude data with said predetermined portion of said second reference data stream containing frequency data to produce frequency spectrogram data representative of the frequency and amplitude of the original analog signal;

means for transforming said predetermined portion of said digital data samples selected from said third data stream into data representative of a time versus amplitude histogram for each discreet frequency;

means for providing selected waveform parameters;

means for comparing said histogram data with said selected waveform parameters and producing addressable waveform data representative of the waveform of the original analog signal;

means for sequentially assembling and storing said frequency spectrogram data and said amplitude reference data of said first data stream and said addressable waveform data for subsequent use.

2. A microcomputer recording and playback system for recording analog signals in digital data form and for playback by decoding the digital data and converting it to analog audio signals comprising:

converting means for converting an analog audio signal into at least three digital data streams, wherein the first of said digital data streams is a reference signal representative of the amplitude of a preselected range of audio frequencies in a relatively broadband width, and wherein the second of said data streams is produced by filtering the analog signal to produce a data stream indicative of a plurality of discrete frequencies encompassed by the bandwidth represented by said first data stream; and

wherein the third of said digital data streams is a reference signal representative of the amplitude of the signal for each of said plurality of discrete frequencies;

sampling means for producing a sequential stream of digital data samples in each of said digital data streams,

selection means for selecting a predetermined portion of the digital data samples produced by said sampling means in each digital data stream;

means for separately storing each of said predetermined portions of said digital data streams;

means for comparing said predetermined portion of said first reference data stream containing amplitude data with said predetermined portion of said second reference data stream containing frequency data to produce frequency spectrogram data representative of the frequency and amplitude of the original analog signal;

means for transforming said predetermined portion of said digital data samples selected from said third data stream into data representative of a time versus amplitude histogram for each discreet frequency;

means for providing selected waveform parameters;

means for comparing said histogram data with said selected waveform parameters and producing addressable waveform data representative of the waveform of the original analog signal;

means for sequentially assembling and storing said frequency spectrogram data and said amplitude reference data of said first data stream and said addressable waveform data for subsequent use; and

playback means for converting said digital data streams to analog data for subsequent reproduction comprising;

addressing means for selecting said stored addressable waveform data representative of the original analog signal; and

oscillator means for producing an analog signal responsive to said addressable waveform data, said frequency spectrogram data, and said amplitude reference data to produce a resultant analog signal suitable for use in a reproduction device.

3. The system of claim 2 wherein said analog signals are audio signals and said resultant analog signal is suitable for use in an audio reproduction device.

4. The system of claim 3 further comprising:

means for transmitting said frequency spectrogram data, amplitude reference data and addressable waveform data by an rf signal to said playback means.

5. A microcomputer playback system for reproducing an original analog signal from stored digital data comprising:

addressing means for selecting stored waveform data representative of analog signal waveforms detected by a recording apparatus; and

oscillator means for producing an analog signal responsive to said selected waveform data and associated amplitude data to reproduce said original analog signal.

6. The system of claim 5 wherein said original analog signal is an audio signal.

7. An apparatus for recording incoming signals in digital form comprising:

means for providing an analog signal representative of an incoming signal;

data acquisition means for sampling and digitizing said analog signal to produce a full spectrum amplified digital signal and filtering said analog signal at a plurality of discrete frequencies to produce a filtered analog signal and sampling and digitizing said filtered analog signal to produce frequency spectrograms;

means for transforming said filtered analog signal into a plurality of amplitude histograms corresponding to said plurality of discreet frequencies;

buffer means for storing said plurality of amplitude histograms;

waveform analyzer means for extracting characteristic waveforms from said plurality of histograms and generating waveform tables in the form of a computer readable data base from said characteristic waveforms;

record assembler means for generating assembled records for storage from said waveform tables, said frequency spectrograms and said full spectrum amplitude digital signal.

8. The apparatus of claim 7 wherein said waveform analyzer means includes means for generating waveform tables using a Fast Fourier Transform.

9. The apparatus of claim 7 wherein said waveform analyzer means includes means for generating waveform tables using a Fast Delta Hademard Transform.

10. The apparatus of claim 7 wherein said waveform analyzer means includes means for generating waveform tables using the B-splines type of cubic splines transform.

11. The apparatus of claim 7 wherein said analog signal is an audio signal and wherein said record assembler means is a disk record assembler for generating assembled disk records for storage by a disk read/write module.

12. The apparatus of claim 11 wherein said means for providing an analog signal is a medical data detection device.

13. The apparatus of claim 11 wherein said means for providing an analog signal is an entry recognition data detection device in a security system.

14. The apparatus of claim 11 wherein said means for providing an analog signal is a vibration transducer in an incipient mechanical failure detection and alarm system.

15. The apparatus of claim 7 wherein said analog signal is an audio signal and said apparatus further including playback means for converting said assembled records into analog signals, wherein said playback analog signals are used to stimulate the auditory nerves in the hearing impaired.

16. The apparatus of claim 7 wherein said means for providing an analog signal is an acoustic rangefinder in an inventory recording and analysis system.

17. The apparatus of claim 7 wherein said means for providing an analog signal is a seismic searcher.

18. A method of recording analog signals in digital form comprising the steps of:

converting said analog signal into at least three digital data streams, wherein the first of said digital data streams is a reference signal representative of the sum of the amplitudes of a preselected range of frequencies in a relatively broadband width, and wherein the second of said data streams is produced by filtering the analog signal to produce a plurality of frequency channels indicative of a series of discrete frequencies encompassed by the bandwidth of said first data stream; and

wherein the third of said digital data streams is a series of reference signals representative of amplitude signals of said second data stream frequency channels;

producing a sequential stream of digital data samples in each of said digital data streams;

selecting a predetermined portion of each said digital data sample of each said digital data stream;

storing each of said selected predetermined portions of said digital data samples;

comparing said predetermined portion of said first digital data stream containing amplitude data with said predetermined portion of said second data stream containing frequency data to produce frequency spectrogram data representative of the frequency and amplitude of the original analog signal;

transforming said predetermined portion of said data samples selected from said third data stream into data representative of a time versus amplitude histogram for each said discreet frequency providing selected waveform parameters;

comparing said histogram data with said selected waveform parameters and producing addressable data representative of the waveform of the original analog signal;

assembling and storing said frequency spectrogram data and said amplitude reference data of said first data stream and said addressable waveform data for subsequent use.

19. A method of recording analog audio signals in digital data form and converting the digital data back into an analog audio signal capable of being played in an audio reproduction device comprising the steps of:

converting an analog audio signal into at least three digital data streams, wherein the first of said digital data streams is reference signal representative of the sum of the amplitudes of a preselected range of audio frequencies in a relatively broad bandwidth, and wherein the second of said data streams is produced by filtering the analog audio signal to produce a plurality of frequency channels indicative of a series of discrete frequencies encompassed by the bandwidth of said first data stream; and

wherein the third of said digital data streams is a series of reference signals representative of amplitude signals of said second data stream frequency channels;

producing a sequential stream of digital data samples in each of said digital data streams;

selecting a predetermined portion of each said digital data sample of each said digital data stream;

storing each of said selected predetermined portions of said digital data samples;

comparing said predetermined portion of said first digital data stream containing amplitude data with data stream containing frequency data to produce frequency spectrogram data representative of the frequency and amplitude of the original analog signal;

transforming said predetermined portion of said data samples selected from said third data stream into data representative of a time versus amplitude histogram for each said discreet frequency;

comparing said histogram data with said selected waveform parameters and producing addressable data representative of the waveform of the original analog signal;

sequentially assembling and storing said frequency spectrogram data and said amplitude reference data of said first data stream and said addressable waveform data for subsequent use;

addressing the stored addressable waveform data, frequency spectrogram data, and amplitude reference data representative of the original audio signal to produce a resultant signal; and

converting the resultant signal from digital to analog form.

20. The method of claim 19 comprising the further steps of:

transmitting said frequency spectrogram data, said amplitude reference data and said addressable waveform data by an rf signal.

21. A method of recording incoming signals in digital form comprising:

providing a analog signal representative of an incoming signal;

sampling and digitizing said analog signal to produce a full spectrum amplitude digital signal;

filtering said analog signal at a plurality of discrete frequencies to produce a filtered analog signal;

sampling and digitizing said filtered analog signal to produce frequency spectrograms;

generating a plurality histograms from said filtered analog signal representative of the amplitude versus time for each discrete frequency of said plurality of discreet frequencies;

extracting characteristic waveforms from said plurality of histograms; and

generating waveform tables in the form of a computer readable data base from said characteristic waveforms;

generating assembled disk records for storage on a disk read/write module from said waveform tables, said frequency spectrograms and said full spectrum amplitude digital signal.

22. The method of claim 21 wherein said step of generating waveform tables comprises generating waveform tables using a Fast Fourier Transform.

23. The method of claim 21 wherein said step of generating waveform tables comprises generating waveform tables using a Fast Delta Hadamard Transform.

24. The method of claim 21 wherein said step of generating waveform tables comprises waveform tables using the B-splines type of cubic splines transform.

25. A method of reproducing an analog signal from assembled waveform tables generated from histograms of characteristic waveforms of said analog signal, frequency spectrograms and full spectrum digital amplitude signals comprising:

addressing waveform, frequency and amplitude data provided by said histograms, spectrograms and amplitude signals; and

converting said waveform, frequency and amplitude data from digital to analog form.

26. The method of claim 25 further comprising:

transmitting digital data from said assembled waveform tables by an rf signal.