Filtering system for processing signature signals

• US 4,686,655 A
• Filed: 09/27/1982
• Issued: 08/11/1987
• Est. Priority Date: 12/28/1970
• Status: Expired due to Term

• Current Assignee: Gilbert P. Hyatt
• Original Assignee: Gilbert P. Hyatt
• Inventors: Hyatt, Gilbert P.
• Primary Examiner(s): Kyle, Deborah L.
• Assistant Examiner(s): STEINBERGER, BRIAN
• Application Number:
  US06/425,131
• Time in Patent Office: 1,779 Days
• Field of Search: 367/1, 367/2, 367/15, 367/21, 367/22, 367/23, 367/24, 367/38, 367/39, 367/40, 367/41, 367/42, 367/43, 367/56, 367/58, 367/59, 367/68, 367/99, 367/100, 367/131, 367/132, 367/133, 367/134, 367/137 , 367/141, 367/900, 367/901, 367/903, 364/421, 364/432, 364/518, 364/449, 364/602, 364/607, 364/724
• US Class Current: 367/59
• CPC Class Codes: B60R 16/0373 Voice control in general G10L
• CPC Class Codes: F21V 23/00 Arrangement of electric circuit elements in or on lighting devices characterised by cooling arrangements F21V29/508
• CPC Class Codes: G01S 15/897 using application of holographic techniques
• CPC Class Codes: G01S 15/8977 using special techniques for image reconstruction, e.g. FFT, geometrical transformations, spatial deconvolution, time deconvolution
• CPC Class Codes: G01S 7/52026 Extracting wanted echo signals Doppler systems G01S15/50; Doppler short range imaging systems G01S15/8979
• CPC Class Codes: G02F 1/13318 Circuits comprising a photodetector
• CPC Class Codes: G03F 9/7049 Technique, e.g. interferometric
• CPC Class Codes: G03F 9/7088 Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection
• CPC Class Codes: G04G 99/006 Electronic time-pieces using a microcomputer, e.g. for multi-function clocks
• CPC Class Codes: G05B 19/351 the positional error is used to control continuously the servomotor according to its magnitude
• CPC Class Codes: G05B 19/408 characterised by data handling or data format, e.g. reading, buffering or conversion of data
• CPC Class Codes: G05B 19/4083 Adapting programme, configuration
• CPC Class Codes: G05B 19/4086 Coordinate conversions; Other special calculations
• CPC Class Codes: G05B 19/409 characterised by using manual data input [MDI] or by using control panel, e.g. controlling functions with the panel; characterised by control panel details or by setting parameters G05B19/408, G05B19/4093 take precedence
• CPC Class Codes: G05B 19/4093 characterised by part programming, e.g. entry of geometrical information as taken from a technical drawing, combining this with machining and material information to obtain control information, named part programme, for the NC machine
• CPC Class Codes: G05B 19/414 Structure of the control system, e.g. common controller or multiprocessor systems, interface to servo, programmable interface controller
• CPC Class Codes: G05B 19/4142 characterised by the use of a microprocessor G05B19/4141 takes precedence
• CPC Class Codes: G05B 2219/33182 Uart, serial datatransmission, modem
• CPC Class Codes: G05B 2219/34023 Risc processor
• CPC Class Codes: G05B 2219/34098 Slope fitting, fairing contour, curve fitting, transition
• CPC Class Codes: G05B 2219/34471 : Program memory is inhibited, not accessible as long as power fails
• CPC Class Codes: G05B 2219/34472 : Configure alterable memory as read only, to avoid erasing
• CPC Class Codes: G05B 2219/35262 : Macro instruction, canned cycles, subroutines, subprogram
• CPC Class Codes: G05B 2219/35263 : Using variables, parameters in program, macro, parametrized instruction
• CPC Class Codes: G05B 2219/35373 : Data storage, buffer
• CPC Class Codes: G05B 2219/35431 : Interactive
• CPC Class Codes: G05B 2219/35436 : Means, manual input, input reference, hand wheel
• CPC Class Codes: G05B 2219/35453 : Voice announcement, oral, speech input
• CPC Class Codes: G05B 2219/35472 : Mode selection
• CPC Class Codes: G05B 2219/35554 : Mirror, other conversions
• CPC Class Codes: G05B 2219/36152 : Panel
• CPC Class Codes: G05B 2219/36333 : Selection from standard forms, shapes, partprograms, enter value for variable
• CPC Class Codes: G05B 2219/36366 : Data, read in, distribution
• CPC Class Codes: G05B 2219/36379 : Read in
• CPC Class Codes: G05B 2219/36503 : Adapt program to real coordinates, software orientation
• CPC Class Codes: G05B 2219/36546 : Memory protection, protected fields
• CPC Class Codes: G05B 2219/41021 : Variable gain
• CPC Class Codes: G05B 2219/42237 : Pwm pulse width modulation, pulse to position modulation ppm
• CPC Class Codes: G05B 2219/45214 : Gear cutting
• CPC Class Codes: G05B 2219/45215 : Thread cutting
• CPC Class Codes: G05B 2219/49221 : Control of scale
• CPC Class Codes: G05B 2219/50047 : Positioning, indexing
• CPC Class Codes: G05B 2219/50048 : Jogging
• CPC Class Codes: G05B 2219/50083 : Power loss, measures again loss of power
• CPC Class Codes: G05B 2219/50151 : Orient, translate, align workpiece to fit position assumed in program
• CPC Class Codes: G06F 13/12 : using hardware independent of the central processor, e.g. channel or peripheral processor
• CPC Class Codes: G06F 13/16 : for access to memory bus G06F13/28 takes precedence
• CPC Class Codes: G06J 1/00 : Hybrid computing arrangements digitally-programmed analogue computers G06G7/06
• CPC Class Codes: G07G 1/12 : electronically operated digital data processing aspects G06Q20/00
• CPC Class Codes: G10L 19/00 : Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis in musical instruments G10H
• CPC Class Codes: G11C 11/565 : using capacitive charge storage elements
• CPC Class Codes: G11C 16/3418 : Disturbance prevention or evaluation; Refreshing of disturbed memory data
• CPC Class Codes: G11C 16/3431 : Circuits or methods to detect disturbed nonvolatile memory cells, e.g. which still read as programmed but with threshold less than the program verify threshold or read as erased but with threshold greater than the erase verify threshold, and to reverse the disturbance via a refreshing programming or erasing step
• CPC Class Codes: G11C 19/287 : Organisation of a multiplicity of shift registers
• CPC Class Codes: G11C 19/36 : using multistable semiconductor elements
• CPC Class Codes: G11C 27/00 : Electric analogue stores, e.g. for storing instantaneous values
• CPC Class Codes: G11C 27/04 : Shift registers
• CPC Class Codes: G11C 7/1042 : using interleaving techniques, i.e. read-write of one part of the memory while preparing another part
• CPC Class Codes: G11C 7/16 : Storage of analogue signals in digital stores using an arrangement comprising analogue/digital [A/D] converters, digital memories and digital/analogue [D/A] converters
• CPC Class Codes: Y02P 90/02 : Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A filtering system is provided for acquiring and processing signals using a sampled filter for signal separation and signal enhancement; such as for determining locations, distances, and times in a geophysical exploration system. Signature signals permit mixing and seperation with sampled filters, such as for sharing common circuitry and for increasing the amount of acquired information. A sampled filter, such as a digital correlator, is provided for generating high resolution output data in response to low resolution input data processed with low resolution computational circuits. A real-time time-domain correlator is provided with single-bit resolution computational elements to provide improved correlation filtering. A high speed real-time correlator is provided to enhance signals with compositing-after-correlation and with correlation using a plurality of correlation operators.

Claims

1. An acoustic filtering system comprising:

a plurality of signature signal generators being spaced apart, each signature signal generator generating an overlapping signature signal that is overlapping the signature signal generated by at least one of the other spaced apart signature signal generators, each signature signal having a signature that is different from the signature of the signature signal of each of the other spaced apart signature signal generaors for propagating through a propagation medium and

a signature signal processor being spaced apart from each of said plurality of signature signal generators for generating output signal samples in response to the overlapping signature signals propagating through said propagation medium from said plurality of signature signal generators, said signal processor including

(a) a receiver for generating input signature signal samples in response to the overlapping signature signals propagating through said propagation medium from said plurality of signature signal generators,

(b) a plurality of reference signal generators each corresponding with a different one of said signature signal generators in said plurality of signature signal generators and each generating reference signal samples having a signature that is different from the signature of the reference signal samples generated with each of the other reference signal generators and each having a signature that is the same as the signature of the overlapping signature signal generated with the corresponding one of said plurality of signature signal generators, and

(c) a plurality of filter processors each corresponding with a different one of said reference signal generators in said plurality of reference signal generators and each generating output signal samples by filter processing the input signature signal samples generated with said receiver in response to the reference signal samples generated with the corresponding one of the reference signal generators.

2. The system as set forth in claim 1 above, wherein each one of said plurality of spaced apart signature signal generators is a chirp signature signal generator which includes means for generating an overlapping chirp signature signal having a chirp signature that is different from the chirp signature of the overlapping chirp signature signal of each of the other spaced apart chirp signature signal generators for propagating through a seismic propagation medium, wherein said spaced apart signature signal processor is an incremental signature signal processor having means for incrementally generating the output signal samples as digital whole number output signal samples in response to the overlapping chirp signature signals generated with said plurality of chirp signature signal generators propagating through said seismic propagation medium, wherein said receiver includes a seismic transducer for generating the input signature signal samples as incremental seismic chirp input signature signal samples in response to the chirp signature signals propagating through said seismic medium that are generated with said plurality of signature signal generators, wherein said plurality of reference signal generators each include a chirp reference signal generator for generating the reference signal samples as chirp reference signal samples having a chirp signature that is different from the chirp signature of the chirp reference signal samples generated with each of the other chirp reference signal generators and having a chirp signature that is the same as the chirp signature of one of the chirp signature signals generated with one of said plurality of chirp signature signal generators, wherein said plurality of filter processors each includes an incremental correlation processor for generating the output signal samples by correlation filter processing the incremental seismic chirp input signature signal samples generated with said receiver in response to the chirp reference signal samples generated with one of said chirp reference signal generators, wherein said plurality of filter processors are located remote from said receiver, said system further comprising incremental communication means for communicating the incremental seismic chirp input signature signal samples generated with said receiver to said incremental correlation processor, said communicating means comprising means for communicating a sequence of incremental signals from said receiver to said incremental correlation processor for generating the output signal samples in response to the communicated incremental seismic chirp input signature signal samples from said receiver;

said system further comprising compositing means for generating composited output signal samples by compositing the corresponding output signal samples from each of the plurality of filter processors and display means for displaying the composited output signal samples.

3. The system as set forth in claim 1 above, where said receiver is an incremental receiver for generating the input signature signal samples as incremental input signature signal samples in response to the overlapping signature signals propagating through said medium that are generated with said plurality of signature signal generators and where each of said plurality of filter processors is an incremental filter processor for generating the output signal samples as multiple bit digital output signal samples by incremental filtering processing the incremental input signature signal samples generated with said incremental receiver in response to the reference signal samples generated with said corresponding one of the reference signal generators.

4. The system as set forth in claim 1 above, wherein each of said plurality of filter processors includes:

output means for storing the output signal samples and

update means for updating the output signal samples stored in said output means in response to the filter processing of the input signature signal samples as they are generated with said receiver, said update means including product means for generating product signal samples as a product of an input signature signal sample generated with said receiver and a plurality of reference signal samples generated with said corresponding one of the reference signal generators and summing means for adding the product signal samples generated with said product means to the output signal samples stored in said output means.

5. The system as set forth in claim 1 above, wherein each of said reference signal generators includes means for generating the reference signal samples as single bit resolution digital reference signal samples.

6. The system as set forth in claim 1 above, wherein each of said plurality of filter processors includes means for storing the output signal samples and means for updating the output signal samples stored in said output means to have better digitial resolution then said input signature signal samples generated with said receiver.

7. The system as set forth in claim 1 above, wherein said receiver includes means for generating the input signature signal samples as incremental input signature signal samples in response to the overlapping signature signals propagating through said medium from said plurality of signature signal generators, wherein each of said plurality of filter processors includes an incremental processor for generating the output signal samples as multiple bit digital output signal samples in response to the incremental input signature signal samples generated with said receiver, and wherein the incremental processor included in each of said plurality of filter processors includes means for processing the incremental input signature signal samples with the reference signal samples generated with the corresponding one of the reference signal generators to separate out signature components of the incremental input signature signal samples to generate the output signal samples.

8. The system as set forth in claim 1 above, wherein each of said plurality of filter processors includes a correlator for generating the output signal samples by correlation filter processing of the input signature signal samples generated with said receiver in response to the reference signal samples generated with the corresponding one of the reference signal generators.

9. The system as set forth in claim 1 above, wherein said system is an underwater geophysical exploration system, wherein said receiver includes means for generating the input signature signal samples in response to the input signature signature signal samples having geophysical exploration-related seismic information, and wherein each of said plurality of filter processors includes means for generating the output signal samples as underground structure-related output signal samples in response to the geophysical exploration-related seismic information in the input signature signal samples.

10. The system as set forth in claim 1 above, wherein each of said plurality of filter processors includes:

multiplying means for generating product signal samples by multiplying the input signature signal samples generated with said receiver and the reference signal samples generated with the corresponding one of the reference signal generators and

summing means for generating the output signal samples by summing the product signal samples generated with said multiplying means.

11. The system as set forth in claim 10 above, wherein said multiplying means includes means for generating the product signal samples by multiplying each of the input signature signal samples generated with said receiver by a plurality of the reference signal samples generated with the corresponding one of the reference signal generators before multiplying a next input signal sample generated with said receiver by a plurality of reference signal samples generated with the corresponding one of the reference signal generators.

12. The system as set forth in claim 10 above, wherein said summing means includes means for generating the output signal samples as composited summed filtered signal samples by compositing the output signal samples.

13. The system as set forth in claim 1 above;

wherein each of said plurality of filter processors includes means for fully processing an input signature signal sample generated with said receiver prior to processing a next input signature signal sample with the same one of the plurality of filter processors.

14. The system as set forth in claim 1 above, wherein each of said filter processors includes:

multiplying means for generating product signal samples by multiplying the input signature signal samples generated with said receiver and the reference signal samples generated with the corresponding one of the reference signal generators;

a memory for storing the output signal samples;

summing means for updating the output signal samples stored in said memory by summing the product signal samples generated with said multiplying means with the output signal samples stored in said memory; and

means for outputting the output signal samples stored in said memory while the updating of the output signal samples is being performed with said summing means.

15. The system as set forth in claim 1 above, wherein each of said plurality of filter processors, includes an output memory for storing the output signal samples generated in the particular filter processor;

means for successively outputting the output signal samples stored in said output memory; and

means for building up magnitude of the output signal samples as the output signal samples are successively output.

16. The system as set forth in claim 1 above, wherein each of said plurality of filter processors includes means for generating the output signal samples to have greater signal to noise ratio than the input signature signal samples generated with said receiver.

17. The system as set forth in claim 1 above, wherein each of said filter processors includes a memory for storing the output signal samples, means for accessing an output signal sample stored in said memory, means for updating the output signal sample accessed from said memory with an output signal sample generated with the related one of the filter processors, means for outputting the updated output signal sample, and means for storing the updated output signal sample in said memory.

18. A filtering system comprising:

a plurality of signature signal generators each generating a signature signal having a signature that is different from the signature of the signature signal of each of the other signature signal generators for propagating through a propagation medium;

a combiner for generating a combined signature signal by combining the signature signals generated by said plurality of signature signal generators;

a transmitter for transmitting the combined signature signal generated with said combiner; and

a signature signal processor being spaced apart from said transmitter for generating output signal samples by processing the combined signature signal transmitted with said transmitter, said signature signal processor including

(a) a receiver for generating input signature signal samples in response to receiving the combined signature signal transmitted with said transmitter,

(b) a plurality of reference signal generators each corresponding to a differrent one of said signature signal generators included in said plurality of signature signal generators and each generating reference signal samples having a signature that is different from the signature of the reference signal samples generated with each of the other reference signal generators and having a signature that is the same as the signature of one of the signature signals generated with the corresponding one of said plurality of signature signal generators, and

(c) a plurality of filter processors each corresponding to a different one of said reference signal generators and each generating output signal samples by filter processing the input signature signal samples generated with said receiver in response to the reference signal samples generated with the corresponding one of the reference signal generators.

19. The system as set forth in claim 18 above, wherein each of said plurality of filter processors includes multiplying means for multiplying a plurality of the reference samples generated with the corresponding one of the reference signal generators by a single input signature signal sample generated with said receiver to generate a plurality of product signal samples before multiplying a reference signal sample generated with the corresponding one of the reference signal generators by a next input signature signal sample generated with said receiver.

20. The system as set forth in claim 18 above, wherein each of said filter processors includes a memory for storing the output signal samples;

means for updating the output signal samples stored in said memory; and

means for outputting the output signal samples updated with said updating means.

21. A filtering system comprising:

a first signature signal generator located at a first position for generating a first signature signal having a first signature to propagate from said first position;

a second signature signal generator located at a second position that is different from said first position for generating a second signature signal having a second signature that is different from said first signature to propagate from said second position; and

a signature signal processor for processing signature signals, said signature signal processor including

(a) receiving means for receiving the first signature signal propagating from said first position and the second signature signal propagating from said second position combined together as a signature input signal,

(b) input means for generating input signature signal samples in response to the signature input signal from said receiving means,

(c) a first reference signal generator for generating first reference signal samples having said first signature,

(d) a second reference signal generator for generating second reference signal samples having said second signature,

(e) a first correlation filter for generating first correlation output signal samples related to said first signature signal generated with said first signature signal generator by correlation processing the input signature signal samples generated with said input means in response to the first reference signal samples generated with said first reference signal generator,

(f) a second correlation filter for generating second correlation output signal samples related to said scond signature signal generated with said second signature signal generator by correlation processing the input signature signal samples generated with said input means in response to the second reference signal samples generated with said second reference signal generator,

(g) first output means for determining position of said signature signal processor relative to said first signature signal generator in response to the first correlation output signal samples generated with said first correlation filter, and

(h) second output means for determining position of said signature signal processor relative to said second signature signal generator in response to the second correlation output signal samples generated with said second correlation filter.

22. The system as set forth in claim 21 above, wherein said first correlation filter includes first product means for generating first product signal samples as a product of the input signature signal samples generated with said input means and the first reference signal samples generated with said first reference signal generator and first summing means for adding the first product signal samples to the first correlation output signal samples and wherein said second correlation filter includes second product means for generating second product signal samples as a product of the input signature signal samples generated with said input means and the second reference signal samples generated with said second reference signal generator and second summing means for adding the second product signal samples to the second correlation output signal samples.

23. A filter processing system comprising:

a plurality of signature signal generators being located at different positions, each signal signature generator generating an overlapping signature signal for propagating through a propagation medium and overlapping the signature signal generated by at least one of the other signature signal generators, each signature signal having a signature that is different from the signature of the signature signal of each of the other signature signal generators and having a signature that is separable from the signature of the signature signal of each of the other signature signal generators and

a signature signal processor being located at a position different from the position of each of said plurality of signature signal generators for generating output signal samples in response to the overlapping signature signals propagating through said propagation medium from said plurality of signature signal generators, said signature signal processor including

(a) a receiver for generating input signature signal samples in response to the overlapping signature signals propagating through said medium from said plurality of signature signal generators,

(b) a plurality of reference signal generators each corresponding with a different one of said signature signal generators in said plurality of signature signal generators and each generating reference signal samples having a signature that is different from the signature of the reference signal samples generated with each of the other reference signal generators and having a signature that is the same as the signature of the overlapping signature signal generated with the corresponding one of said plurality of signature signal generators,

(c) a plurality of correlation filter processors each corresponding with a different one of said reference signal generators in said plurality of reference signal generators and each generating correlation output signal samples by correlation filter processing of the input signature signal samples generated with said receiver in response to the reference signal samples generated with the corresponding one of the reference signal generators, and

(d) output means for determining position of said signature signal processor relative to each of said plurality of signature signal generators in response to the correlation output signal samples generated with each of said correlation filter processors.

24. The system as set forth in claim 23 above, wherein said receiver includes means for generating the input signature signal samples as incremental input signature signal samples in response to the overlapping signature signals propagating through said medium from said plurality of signature signal generators.

25. A acoustic signal processing system comprising:

a first acoustic signal generating means located at a first shotpoint for generating a first acoustic signal to propagate from said first shotpoint, said first acoustic signal generating means including means for generating said first acoustic signal having a first signature;

a second acoustic signal generating means located at a second shotpoint that is different from the first shotpoint for generating a second acoustic signal to propagate from said second shotpoint, said second acoustic signal generating means including means for generating the second acoustic signal having a second signature that is different from said first signature and means for generating said second acoustic signal overlapping with said first acoustic signal; and

an acoustic signal processor for processing acoustic signals, said acoustic signal processor including

(a) receiving means for generating an acoustic input signal by receiving the first acoustic signal propagating from said first acoustic signal generating means and the second acoustic signal propagating from said second acoustic signal generating means overlapping therebetween,

(b) first reference means for generating a first reference signal having said first signature,

(c) second reference means for generating a second reference signal having said second signature,

(d) first filter means for generating a first output signal related to said first acoustic signal generated with said first acoustic signal generating means by processing the acoustic input signal received with said receiving means under control of the first reference signal generated with said first reference means, and

(e) second filter means for generating a second output signal related to said second acoustic signal generated with said second acoustic signal generating means by processing the acoustic input signal received with said receiving means under control of the second reference signal generated with said second reference means.

26. The system as set forth in claim 25 above, where said first acoustic signal generating means includes means for generating the first acoustic signal as an underwater acoustic signal to propagate through water from said first shotpoint, where said first acoustic signal generating means includes means for generating said first underwater acoustic signal having a first signature in the form of an up chirp signature, where said second acoustic signal generating means includes means for generating a second acoustic signal as an underwater acoustic signal to propagate through water from said second shotpoint, where said second acoustic signal generating means includes means for generating the second underwater acoustic signal having a second signature in the form of a down chirp signal that is different from said first up chirp signature and that is separable from said first up chirp signature, where said receiving means includes a transducer for simultaneoulsy receiving the first underwater acoustic signal and the second underwater acoustic signal combined together as an underwater acoustic input signal and sampling means for generating the underwater acoustic input signal as underwater acoustic incremental input signal samples, where said first reference means includes an analog CCD read only memory for generating the first reference signal as first analog reference signal samples having said first up chirp signature, where said second reference means includes an analog CCD read only memory for generating the second reference signal as second analog reference signal samples having said second down chirp signature, where said first filter means includes a first incremental correlator for incrementally generating the first output signal as first correlated whole number output signal samples related to said first underwater acoustic signal generated with said first acoustic signal generating means by processing the underwater acoustic incremental input signal samples generated with said sampling means and the first analog reference signal samples generated with said first reference means, where said second filter means includes a second incremental correlator for incrementally generating the second output signal as second correlated whole number output signal samples related to said second underwater acoustic signal generated with said second acoustic signal generating means by processing the underwater acoustic incremental input signal samples generated with said sampling means and the second analog reference signal samples generated with said second reference means;

said system further comprising compositing means for generating a composited output signal by compositing the first output signal generated by said first filter means with the second output signal generated by said second filter means and display means for displaying the composited output signal.

27. A filter processing system comprising:

a first signature signal generating means located at a first position for generating a first signature signal to propagate from said first position, said first signature signal generating means including means for generating said first signature signal having a first signature;

a second signature signal generating means located at a second position that is different from said first position for generating a second signature signal to propagate from said second position, said second signature signal generating means including means for generating the second signature signal having a second signature that is different from said first signature and means for generating said second signature signal overlapping with said first signature signal; and

a signature signal processor located at a third position that is different from said first position and that is different from said second position for processing signature signals, said signature signal processor including

(a) receiving means for receiving the first signature signal propagating from said first signature signal generating means and the second signature signal propagating from said second signature signal generating means having overlapping therebetween as a signature input signal,

(b) first reference means for generating a first reference signal having said first signature,

(c) second reference means for generating a second reference signal having said second signature,

(d) a first correlation filter processor for generating a first correlated output signal by correlation processing the signature input signal received with said receiving means under control of the first reference signal generated with said first reference means,

(e) a second correlation filter processor for generating a second correlated output signal by correlation processing the signature input signal received with said receiving means under control of the second reference signal generated with said second reference means,

(f) first position output means for generating a first position output signal to identify position of said signature signal processor relative to said first signature signal generating means in response to the first correlation output signal generated with said first correlation filter processor, and

(g) second position output means for generating a second position output signal to identify position of said signature signal processor relative to said second signature signal generating means in response to the second correlation output signal generated with said second correlation filter processor.

28. A filtering system for eliminating listening periods comprising:

a signature signal generator for generating a signature signal without a listening period;

a transmitter for transmitting the signature signal generated with said signature signal generator to propagate through a propagation medium without a listening period; and

a signature signal processor for generating output filtered signal samples without a listening period by processing the signature signal transmitted with said transmitter, said signature signal processor including

(a) a receiver for generating input signature signal samples without a listening period in response to receiving the signature signal transmitted with said transmitter,

(b) a reference signal generator for generating signature reference signal samples without a listening period,

(c) a filter processor for generating output filtered signal samples without a listening period by filter processing the input signature signal samples generated with said receiver in response to the reference signal samples generated with said reference signal generator, and

(d) a memory for storing the output filtered signal samples generated by said filter processor.

29. The system as set forth in claim 28 above, further comprising:

means for updating the output filtered signal samples stored in said memory with the output filtered signal samples generated with said filter processor and

means for outputting the output filtered signal samples stored in said memory simultaneously with the updating of the output filtered signal samples stored in said memory with said update means.

30. A filtering system comprising:

a signature signal generator for generating a sequence of a plurality of signature signals having different signatures therebetween to propagate through a propagation medium;

a transmitter for transmitting the sequence of the plurality of signature signals generated with said signature signal generator; and

a signature signal processor for generating an output filtered signal by processing the sequence of the plurality of signature signals transmitted with said transmitter, said signature signal processor including

(a) a receiver for generating an input signature signal in response to receiving the sequence of the plurality of signature signals transmitted with said transmitter,

(b) a reference signal generator for generating a sequence of a plurality of reference signals having different signatures therebetween, where each of the plurality of reference signals in the sequence of the plurality of reference signals has a signature the same as the signature of a corresponding sequential signature signal generated with said signature signal generator,

(c) a filter processor for generating an output filtered signal by filter processing the input signature signal generating with said receiver in reponse to the sequence of the plurality of reference signals generated with said reference signal generator, and

(d) a memory for storing the output filtered signal generated by said filter processor.

31. A filtering system comprising:

input means for generating an input signal having a plurality of different overlapping signature signal components each having a different signature;

reference means for generating a plurality of reference signals each having a different signature corresponding to the signature of one of the plurality of different signature signal components in the input signal generated with said input means; and

a plurality of correlation processors for separating the different overlapping signature signal components in the input signal generated with said input means, wherein each of said correlation processors includes product means for generating a product signal as a product of the input signal and a corresponding one of the reference signals generated with said reference means and summing means for adding the product signal to generate an output signal related to a corresponding one of the plurality of different overlapping signature signal components in the input signal generated with said input means.

32. The system as set forth in claim 31 above, wherein said reference means includes means for generating the reference signals as single bit resolution digital reference signal samples.

33. The system as set forth in claim 31 above, wherein each of said correlation processors includes means for updating the output signal to have better digital resolution then said input signal.

34. The system as set forth in claim 31 above, wherein the output signals represents a geophysical image, wherein the output signals include a plurality of digital output signals, and wherein said system is arranged for generating the output signals as correlation filtered output signals.

35. The system as set forth in claim 31 above, where said input means includes means for generating the input signal as a plurality of input signal samples and wherein said reference means includes means for generating the plurality of reference signals each having a plurality of reference signal samples;

wherein said product means included in each of said correlation processors in said plurality of correlation processors includes means for generating the product signal having a plurality of product signal samples by multiplying each of the input signal samples by a plurality of reference signal samples before multiplying a next input signal sample by the reference signal samples.

36. The system as set forth in claim 31 above;

wherein said input means includes means for generating the input signal as a plurality of input signal samples and wherein each correlation processor included in said plurality of correlation processors includes means for fully processing an input signal sample prior to processing the next input signal sample with said product means and with said summing means.

37. The system as set forth in claim 31 above, wherein said summing means in each of said plurality of correlation processors includes means for generating the output signal as a plurality of output signal samples;

said system further comprising means for successively outputting the output signal samples generated by said summing means in each of said plurality of correlation pfocessors and means for building up the magnitude of the output signal samples as the output signal samples are successively output.

38. The system as set forth in claim 31 above, further comprising means for outputting the output signal simultaneously with the adding of the product signal with said summing means.

39. The system as set forth in claim 31 above, further comprising a memory for storing the output signal generated with said summing means in each of said correlation processors, means for accessing the output signal stored in said memory, means for updating the accessed output signal with said summing means by adding the product signal, and means for storing the updated output signal into said memory.

40. A filtering system comprising:

a first signature signal generator located at a first position for generating a first signature signal to propagate from said first position, said first signature signal generator including means for generating said first signature signal having a first signature;

a second signature signal generator located at a second position that is different from said first position for generating a second signature signal to propagate from said second position, said second signature signal generator including means for generating the second signature signal having a second signature that is different from said first signature and means for generating said second signature signal overlapping with said first signature signal; and

a signature signal processor for processing signature signals, said signature signal processor including

(a) a receiver for receiving the first signature signal propagating from said first signature signal generator and the second signature signal propagating from said second signature signal generator, said first signature signal and said second signature signal being combined together and overlapping therebetween as a signature input signal,

(b) input means for generating single bit resolution digital input signature signal samples in response to the signature input signal from said receiving means,

(c) first reference means for generating a first reference signal having said first signature,

(d) second reference means for generating a second reference signal having said second signature,

(e) first filter means for generating a first output signal related to said first signature signal generated with said first signature signal generating means by processing the single bit resolution digital input signature signal samples generated with said input means in response to the first reference signal generated with said first reference means, and

(f) second filter means for generating a second output signal related to said second signature signal generated with said second signature signal generating means by processing the single bit resolution digital input signature signal samples generated with said input means in response to the second reference signal generated with said second reference means.

41. A filtering system comprising:

a first signature signal generating means located at a first position for generating a first signature signal and a second signature signal to propagate from said first position, said first signature signal generating means including

(a) first signature means for generating said first signature signal having a first signature,

(b) second signature means for generating said second signature signal having a second signature that is different from said first signature,

(c) combining means for generating a first combination signal by combining the first signature signal generated by said first signature means and the second signature signal generated by said second signature means, and

(d) a first transmitter for transmitting the first combination signal;

a second signature signal generating means located at a second position that is different from said first position for generating a third signature signal and a forth signature signal to propagate from said second position, said second signature signal generating means including

(a) third signature means for generating said third signature signal having a third signature that is different from said first and second signatures,

(b) forth signature means for generating said forth signature signal having a forth signature that is different from said first through third signatures,

(c) combining means for generating a second combination signal by combining the third signature signal generated by said third signature means and the forth signature signal generated by said forth signature means, and

(d) a second transmitter for transmitting the second combination signal; and

a signature signal processor for processing signature signals, said signature signal processor including

(a) receiving means for generating an input signature signal by receiving the first combination signal transmitted with said first transmitter combined together with the second combination signal transmitted with said second transmitter,

(b) input means for generating input signature signal samples in response to the input signature signal from said receiving means,

(c) first reference means for generating a first reference signal having said first signature,

(d) second reference means for generating a second reference signal having said second signature,

(e) third reference means for generating a third reference signal having said third signature,

(f) forth reference means for generating a forth reference signal having said forth signature,

(g) a first filter processor for generating a first output signal related to said first signature signal generated with said first signature signal generating means by processing the input signature signal samples generated with said input means in response to the first reference signal generated with said first reference means,

(h) a second filter processor for generating a second output signal related to said second signature signal generated with said second signature signal generating means by processing the input signature signal samples generated with said input means in response to the second reference signal generated with said second reference means,

(i) a third filter processor for generating a third output signal related to said third signature signal generated with said third signature signal generating means by processing the input signature signal samples generated with said input means in response to the third reference signal generated with said third reference means, and

(j) a forth filter processor for generating a forth output signal related to said forth signature signal generated with said forth signature signal generating means by processing the input signature signal samples generated with said input means in response to the forth reference signal generated with said forth reference means.

42. A filter system comprising:

a plurality of signature signal generators being spaced apart, each signature signal generator generating an overlapping signature signal that is overlapping the signature signals generated by all of the other spaced apart signature signal generators for propagating through a propagation medium, each signature signal having a signature that is different from the signature of the signature signal of each of the other spaced apart signature signal generators and

a signature signal processor being spaced apart from each of said plurality of signature signal generators for generating output signal samples in response to the overlapping signature signals propagating through said propagation medium from said plurality of signature signal generators, said signature signal processor including

(a) a receiver for generating input signature signal samples in response to the overlapping signature signals propagating through said medium from said plurality of signature signal generators,

(b) a plurality of reference signal generators each corresponding to one of the signature signal generators in said plurality of signature generators and each generating reference signal samples having a signature that is different from the signature of the reference signal samples generated with each of the other reference signal generators and each having a signature that is the same as the signature of the overlapping signature signal generated with the corresponding one of said plurality of signature signal generators,

(c) a plurality of correlation filter processors each corresponding with one of the reference signal generators in said plurality of reference signal generators and each generating output signal samples by filter processing the input signature signal samples generated with said receiver in response to the reference signal samples generated with the corresponding one of the reference signal generators that is different from the reference signal generators corresponding to the other filter processors in said plurality of filter processors,

(d) a memory for storing the output signal samples generated with said plurality of filter processors; and

(e) each of means for determining position of said plurality of signature signal generators in response to the output signal samples stored in said memory.

43. The system as set forth in claim 42 above, wherein each of said correlation filter processors includes:

product means for generating product signal samples by multiplying the input signature signal samples generated with said receiver and the reference signal samples generated with the corresponding one of the reference signal generators;

summing means for updating the output signal samples stored in said memory by summing the product signal samples generated with said product means with the output signal samples stored in said memory; and

output means for outputting the output signal samples while updating of the output signal samples is being performed with said summing means.

44. The system as set forth in claim 42 above, wherein each of said plurality of correlation filter processors includes updating means for updating the output signal samples stored in said memory in response to the filter processing of the input signature samples generated with said receiver and wherein said memory includes output means for outputting the output signal samples stored in said memory at the same time that the output signal samples stored in said memory are being updated with said updating means.

45. A system for determining location of a plurality of objects, said system comprising:

a plurality of signature signal generators being spaced apart, each signature signal generator generating an overlapping signature signal for propagating through a propagation medium that is overlapping the signature signal generated by at least one of the other spaced apart signature signal generators, each signature signal having a signature that is different from the signature of the signature signal of each of the other spaced apart signature signal generators and

a correlation signal processor being spaced apart from each of said plurality of signal generators for determining location of an object in response to the overlapping signature signals propagating through said propagation medium from said plurality of signature signal generators, said signal processor including

(a) a receiver for generating input signature signal samples in response to the overlapping signature signals propagating through said medium from said plurality of signature signal generators,

(b) a plurality of reference signal generators each generating reference signal samples having a signature that is different from the signature of the reference signal samples generated with each of the other reference signal generators and each having a signature that is the same as the signature of the overlapping signature signal generated with a corresponding one of said plurality of signature signal generators,

(c) a plurality of correlation filter processors each generating correlated output signal samples by correlation filter processing the input signature signal samples generated with said receiver in response to the reference signal samples generated with a corresponding one of the reference signal generators that is different from the reference signal generators corresponding to the other filter processors in said plurality of filter processors, and

(d) output means for determinating location of an object in response to the correlated output signal samples from each of the plurality of correlation filter processors.

46. A filtering system for determining location of a plurality of objects, said system comprising:

a plurality of signature signal generators being spaced apart, each generating a signature signal for propagating through a propagation medium having a signature that is different from the signature of the signature signal of each of the other spaced apart signature signal generators and

a correlation signal processor being spaced apart from each of said plurality of signal generators for generating correlated output signal samples in response to the overlapping signature signals propagating through said propagation medium from said plurality of signature signal generators, said signal processor including

(a) a receiver for generating input signature signal samples in response to the overlapping signature signals generated with said plurality of signature signal generators and propagating through said medium,

(b) a plurality of reference signal generators each generating reference signal samples having a signature that is different from the signature of the reference signal samples generated with each of the other reference signal generators,

(c) a plurality of correlation filter processors each generating correlated output signal samples by correlation filter processing the input signature signal samples generated with said receiver in response to the reference signal samples generated with one of the reference signal generators, and

(d) output means for determinating location of an object in response to the correlated output signal samples from each of the plurality of correlation filter processors.

47. A filter system comprising:

a first signature signal generator located at a first position for generating a first signature signal to propagate from said first position, said first signature signal generator including means for generating said first signature signal having a first signature;

a second signature signal generator located at a second position that is different from said first position for generating a second signature signal to propagate from said second position, said second signature signal generator including means for generating the second signature signal having a second signature that is different from said first signature and means for generating said second signature signal overlapping with said first signature signal; and

a signature signal processor located at a third position that is different from said first position and said second position for processing signature signals, said signature signal processor including

(a) a receiver for receiving the first signature signal propagating form said first signature signal generator and the second signature signal propagating from said second signature signal generator, said first signature signal and said second signature signal being combined together and overlapping therebetween as a signature input signal,

(b) an input means for generating input signature signal in response to the signature input signal from said receiver,

(c) first reference means for generating a first reference signal having said first signature,

(d) second reference means for generating a second reference signal having said second signature,

(e) first filter means for generating a first output signal related to said first signature signal generated with said first signature signal generating means by processing the input signature signal generated with said input means under control of the first reference signal generated with said first reference means, and

(f) second filter means for generating a second output signal related to said second signature signal generated with said second signature signal generating means by processing the input signature signal generated with said input means under control of the second reference signal generated with said second reference means.