Variable length ranging and direction-finding signals constructed from bandlimited kernels and sparse spreading sequences

• US 8,391,336 B2
• Filed: 03/07/2011
• Issued: 03/05/2013
• Est. Priority Date: 03/07/2011
• Status: Active Grant

• Current Assignee: Rosemount Tank Radar AB (Emerson Electric Company)
• Original Assignee: APM Automation Solutions Ltd. (Emerson Electric Company)
• Inventors: Chiskis, Alex
• Primary Examiner(s): Flores, Leon
• Application Number:
  US13/041,461
• Publication Number:
  US 20120230371A1
• Time in Patent Office: 729 Days
• Field of Search: 375/130, 375/140, 375/141, 375/142, 375/143, 375/146, 375/147, 375/150, 375/152, 375/219, 375/220, 375/295, 375/316, 342/21, 342/25, 342/70, 342/71, 342/72, 342/128, 342/130, 342/132, 342/175, 342/194, 342/195, 342/196, 342/200, 342/201, 342/202, 370/320, 370/334, 370/335, 370/342, 370/343
• US Class Current: 375/146
• CPC Class Codes: G01F 23/284 Electromagnetic waves
• CPC Class Codes: G01F 23/2962 Measuring transit time of reflected waves
• CPC Class Codes: G01S 13/106 using transmission of pulses having some particular characteristics G01S13/12, G01S13/22, G01S13/24, G01S13/26, G01S13/28 and G01S13/30 take precedence
• CPC Class Codes: G01S 13/284 using coded pulses
• CPC Class Codes: G01S 13/88 Radar or analogous systems specially adapted for specific applications electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00
• CPC Class Codes: G01S 15/102 using transmission of pulses having some particular characteristics
• CPC Class Codes: G01S 15/88 Sonar systems specially adapted for specific applications seismic or acoustic prospecting or detecting G01V1/00

Abstract

To generate a pulse for ranging, a kernel is convolved with a spreading sequence. The spreading sequence is parametrized by one or more ordered (length, sparsity) pairs, such that the first sparsity differs from the bit length of the kernel and/or a subsequent sparsity differs from the product of the immediately preceding length and the immediately preceding sparsity. Alternatively, a kernel is convolved with an ordered plurality of spreading sequences, all but the first of which may be non-binary. The pulse is launched towards a target. The reflection from the target is transformed to a received reflection, compressed by deconvolution of the spreading sequence, and post-processed to provide a range to the target and/or a direction of arrival from the target.

Claims

1. A transmitter comprising:

(a) a pulse shaper for generating an input pulse that is a convolution of a kernel parametrized by a bit length and a spreading sequence parametrized by at least one parameter pair that consists of a spreading length and a sparsity, wherein said bit length and said at least one parameter pair form an ordered set that satisfies at least one condition selected from the set consisting of;

(i) a first said sparsity is different from said bit length and

(ii) when said ordered set includes a plurality of said spreading lengths and said sparsities, then at least one said sparsity subsequent to said first sparsity is different from a product of an immediately preceding spreading length and an immediately preceding sparsity;

(b) a mechanism for transforming said input pulse to a transmitted pulse; and

(c) a transducer for launching said transmitted pulse as a signal propagating in a medium.

2. The transmitter of claim 1, wherein said input pulse is a baseband pulse and wherein said mechanism includes a modulator for modulating a carrier wave with said baseband pulse.

3. The transmitter of claim 1, wherein said input pulse is a passband pulse and wherein said mechanism includes a digital-to-analog converter.

4. The transmitter of claim 1, wherein said spreading sequence is parametrized by a plurality of said parameter pairs.

5. The transmitter of claim 1, wherein said signal is electromagnetic.

6. The transmitter of claim 1, wherein said signal is acoustic.

7. A non-contact sensing device, comprising:

(a) a transmitter that includes a pulse shaper for generating an input pulse to be transformed to a transmitted pulse that is launched as a signal that propagates in a medium towards a target, the input pulse being a convolution of a kernel parametrized by a bit length and a spreading sequence parametrized by at least one parameter pair that consists of a spreading length and a sparsity, wherein said kernel length and said at least one parameter pair form an ordered set that satisfies at least one condition selected from the set consisting of;

(i) a first said sparsity is different from said bit length and

(ii) when said ordered set includes a plurality of said spreading lengths and said sparsities, then at least one said sparsity subsequent to said first sparsity is different from a product of an immediately preceding spreading length and an immediately preceding sparsity; and

(b) a receiver that includes;

(i) at least one transducer for coupling to said medium to receive a respective reflection of said signal from said target,

(ii) for each said transducer;

(A) a mechanism for transforming said respective received reflection to a respective received representation of said input pulse, and

(B) a pulse compressor for deconvolving said spreading sequence from said respective received representation of said input pulse, thereby providing a respective compressed pulse, and

(iii) a post-processor for post-processing said at least one respective compressed pulse.

8. The device of claim 7, wherein said input pulse is a baseband pulse and wherein each said mechanism includes a demodulator for demodulating said respective received reflection.

9. The device of claim 7, wherein said input pulse is a passband pulse and wherein each said mechanism includes an analog-to-digital converter.

10. The device of claim 7, wherein said post-processing is for obtaining a respective travel time from said transmitter to each said at least one transducer via said target and for inferring a range to said target from said at least one respective travel time.

11. The device of claim 7, wherein said post-processing is for obtaining a direction of arrival of said at least one received reflection.

12. The device of claim 7, wherein said signal is electromagnetic.

13. The device of claim 7, wherein said signal is acoustic.

14. The device of claim 7, wherein said deconvolving is effected using a matched filter.

15. The device of claim 7, wherein said deconvolving is effected using a mismatched filter.

16. A method of transmitting a signal into a medium, comprising the steps of:

(a) generating an input pulse that is a convolution of a kernel parametrized by a bit length and a spreading sequence parametrized by at least one parameter pair that consists of a spreading length and a sparsity, wherein said bit length and said at least one parameter pair form an ordered set that satisfies at least one condition selected from the set consisting of;

(i) a first said sparsity is different from said bit length and

(ii) when said ordered set includes a plurality of said spreading lengths and said sparsities, then at least one said sparsity subsequent to said first sparsity is different from a product of an immediately preceding spreading length and an immediately preceding sparsity;

(b) transforming said input pulse to a transmitted pulse; and

(c) launching said transmitted pulse into the medium as the signal.

17. A method of non-contact sensing of a target, comprising the steps of:

(a) generating an input pulse that is a convolution of a kernel parametrized by a bit length and a spreading sequence parametrized by at least one parameter pair that consists of a spreading length and a sparsity, wherein said bit length and said at least one parameter pair form an ordered set that satisfies at least one condition selected from the set consisting of;

(i) a first said sparsity is different from said bit length and

(ii) when said ordered set includes a plurality of said spreading lengths and said sparsities, then at least one said sparsity subsequent to said first sparsity is different from a product of an immediately preceding spreading length and an immediately preceding sparsity;

(b) transforming said input pulse to a transmitted pulse;

(c) launching said transmitted pulse as a signal propagating in a medium towards the target;

(d) receiving at least one reflection of said signal from said target;

(e) for each said received reflection;

(i) transforming said each received reflection to a respective received representation of said input pulse, and

(ii) compressing said respective received representation of said input pulse by deconvolving said spreading sequence from said respective received representation of said input pulse, thereby providing a respective compressed pulse; and

(f) post-processing said at least one compressed pulse.

18. A transmitter comprising:

(a) a pulse shaper for generating an input pulse that is a convolution of a kernel and an ordered plurality of spreading sequences, wherein at least one spreading sequence subsequent to a first said spreading sequence is not a binary sequence;

(b) a mechanism for transforming said input pulse to a transmitted pulse; and

(c) a transducer for launching said transmitted pulse as a signal propagating in a medium.

19. The transmitter of claim 18, wherein said input pulse is a baseband pulse and wherein said mechanism includes a modulator for modulating a carrier wave with said baseband pulse.

20. The transmitter of claim 18, wherein said input pulse is a passband pulse and wherein said mechanism includes a digital-to-analog converter.

21. A non-contact sensing device, comprising:

(a) a transmitter that includes a pulse shaper for generating an input pulse to be transformed to a transmitted pulse that is launched as a signal that propagates in a medium towards a target, the input pulse being a convolution of a kernel and an ordered plurality of spreading sequences, wherein at least one spreading sequence subsequent to a first said spreading sequence is not a binary sequence; and

(b) a receiver that includes;

(i) at least one transducer for coupling to said medium to receive a respective reflection of said signal from said target,

(ii) for each said transducer;

(A) a mechanism for transforming said respective received reflection to provide a respective received representation of said input pulse, and

(B) a pulse compressor for deconvolving said spreading sequence from said respective received representation of said input pulse, thereby providing a respective compressed pulse, and

(iv) a post-processor for post-processing said at least one compressed pulse.

22. The device of claim 21, wherein said input pulse is a baseband pulse and wherein each said mechanism includes a demodulator for demodulating said respective received reflection.

23. The device of claim 21 wherein said input pulse is a passband pulse and wherein each said mechanism includes an analog-to-digital converter.

24. The device of claim 21 wherein said post-processing is for obtaining a respective travel time from said transmitter to each said at least one transducer via said target and for inferring a range to said target from said at least one respective travel time.

25. The device of claim 21, wherein said post-processing is for obtaining a direction of arrival of said at least one received reflection.

26. A method of transmitting a signal into a medium, comprising the steps of:

(a) generating an input pulse that is a convolution of a kernel and an ordered plurality of spreading sequences, wherein at least one spreading sequence subsequent to a first said spreading sequence is not a binary sequence;

(b) transforming said input pulse to a transmitted pulse; and

(c) launching said transmitted pulse into the medium as the signal.

27. A method of non-contact sensing of a target, comprising the steps of:

(a) generating an input pulse that is a convolution of a kernel and an ordered plurality of spreading sequences, wherein at least one spreading sequence subsequent to a first said spreading sequence is not a binary sequence;

(b) transforming said input pulse to a transmitted pulse;

(c) launching said transmitted pulse as a signal propagating in a medium towards the target;

(d) receiving at least one reflection of said signal from said target;

(e) for each said received reflection;

(i) transforming said each received reflection to a respective received representation of said input pulse, and

(ii) compressing said respective received representation of said input pulse by deconvolving said spreading sequence from said respective received representation of said input pulse, thereby providing a respective compressed pulse; and

(f) post-processing said at least one compressed pulse.

28. A method of transmitting a signal into a medium, comprising the steps of:

(a) selecting a desired length of an input pulse;

(b) selecting a kernel and a spreading sequence, such that when said kernel is convolved with said spreading sequence without nesting said kernel in said spreading sequence, an output of said convolution is said input pulse having said desired length;

(c) generating said input pulse;

(d) transforming said input pulse into a transmitted pulse; and

(e) launching said transmitted pulse into the medium as the signal.

29. The method of claim 28, wherein said spreading sequence is parametrized by at least one sparsity.

30. A method of transmitting a signal into a medium, comprising the steps of:

(a) generating an input pulse by convolving a kernel with a spreading sequence that is selected so that a length by which said input pulse exceeds a length of said kernel is not determined by said length of said kernel;

(b) transforming said input pulse into a transmitted pulse; and

(c) launching said transmitted pulse into the medium as the signal.

31. A transmitter comprising:

(a) a pulse shaper for generating an input pulse that is a convolution of

(i) a kernel parametrized by a bit length and

(ii) a spreading sequence that is a convolution of a plurality of spreading functions, with each said spreading function parametrized by a respective parameter pair that consists of a spreading length and a sparsity,

wherein said bit length and said parameter pairs form an ordered set that satisfies at least one condition selected from the set consisting of;

(i) a first said sparsity is different from said bit length and

(ii) at least one said sparsity subsequent to said first sparsity is different from a product of an immediately preceding spreading length and an immediately preceding sparsity;

(b) a mechanism for transforming said input pulse to a transmitted pulse; and

(c) a transducer for launching said transmitted pulse as a signal propagating in a medium.

32. The transmitter of claim 31, wherein said pulse shaper is operative to generate said input pulse by a plurality of convolutions equal in number to said plurality of spreading functions, with a first said convolution being a convolution of said kernel with a first said spreading function and each subsequent convolution being a convolution of an output of an immediately preceding convolution with a next said spreading function.

33. A non-contact sensing device, comprising:

(a) a transmitter that includes a pulse shaper for generating an input pulse to be transformed to a transmitted pulse that is launched as a signal that propagates in a medium towards a target, the input pulse being a convolution of

(i) a kernel parametrized by a bit length and

(ii) a spreading sequence that is a convolution of a plurality of spreading functions, with each said spreading function parametrized by a respective parameter pair that consists of a spreading length and a sparsity,

wherein said kernel length and said parameter pairs form an ordered set that satisfies at least one condition selected from the set consisting of;

(i) a first said sparsity is different from said bit length and

(ii) at least one said sparsity subsequent to said first sparsity is different from a product of an immediately preceding spreading length and an immediately preceding sparsity; and

(b) a receiver that includes;

(i) at least one transducer for coupling to said medium to receive a respective reflection of said signal from said target,

(ii) for each said transducer;

(A) a mechanism for transforming said respective received reflection to a respective received representation of said input pulse, and

(B) a pulse compressor for deconvolving said spreading sequence from said respective received representation of said input pulse by a plurality of deconvolutions that is equal in number to said plurality of spreading functions, with a first said deconvolution being a deconvolution of a last said spreading function from said respective received representation of said input pulse and each subsequent said deconvolution being a deconvolution of a preceding said spreading function from an output of an immediately preceding deconvolution, thereby providing a respective compressed pulse, and

(iii) a post-processor for post-processing said at least one respective compressed pulse.

34. The device of claim 33, wherein each said deconvolution is effected using a respective key whose sparsity is equal to said sparsity of said spreading sequence that said respective key deconvolves.