Method and system for waveform independent covert communications

• US 20030228017A1
• Filed: 03/28/2003
• Published: 12/11/2003
• Est. Priority Date: 04/22/2002
• Status: Abandoned Application

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Anderson, Richard Hugh, Beadle, Edward Ray, Dishman, John Fitzgerald
• Application Number:
  US10/400,486
• Publication Number:
  US 20030228017A1
• Time in Patent Office: Days
• US Class Current: 380/270
• CPC Class Codes: G01S 3/74 Multi-channel systems specially adapted for direction-finding, i.e. having a single antenna system capable of giving simultaneous indications of the directions of different signals systems in which the directions of different signals are determined sequentially and displayed simultaneously G01S3/04, G01S3/14
• CPC Class Codes: G06F 18/2134 based on separation criteria, e.g. independent component analysis
• CPC Class Codes: G06F 2218/22 Source localisation; Inverse modelling
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/71052 using decorrelation matrix
• CPC Class Codes: H04K 1/02 by adding a second signal to make the desired signal unintelligible

Abstract

A transmitted signal exploits unique higher order statistics of temporally dependent waveforms to encode message symbols with unique durations enabling low power transmission of the covert message. The message is independent of the characteristics or encoded data of the transmitted waveform. The method uses spatial fourth order cumulants or spatial second order moments in a Blind Source Separation and generalized eigenvalue decomposition to determine unique matrix pencil eigenvalues. Sequential detection in successive blocks determine the duration of the eigenvalue. The durations of the detected eigenvalues are sorted sequentially and can be sorted spatially by Steering vectors, AoA or geolocation into signal tracks that are mapped to recover the transmitted cover message. Generation of the transmitted signals with unique high order statistics may be accomplished using combination of noise generators, temporal filters, signal sources, combiners and switches. The receiver includes a multi-element array and does not need a priori knowledge of the transmitted signal source to recover the message. The methods and apparatus for covert communication does not require typical demodulation. The covert communication system is multiple access.

Claims

1. A communication device for providing a communication signal from a data signal comprised of a sequence of bits, comprising:

a noise generator for generating a first signal comprised of a bit stream;

a filter for receiving said first signal and generating a temporal dependence between immediately adjacent bits in said first signal to thereby provide a third signal;

a plurality of signal sources each providing a source signal with a characteristic unique from the others;

a switch for selectively operatively connecting as a function of said data signal one of said plurality of signal sources in sequence to a combining means to thereby provide a second signal; and

said combining means for combining said third signal with said second signal to thereby provide the communication signal from said data signal.

2. The communication device of claim 1 wherein said noise generator is a Laplacian noise generator.

3. The communication device of claim 1 wherein said noise generator generates a signal with a distribution function for which the kurtosis is greater than the kurtosis of a Gaussian distribution function.

4. The communication device of claim 1 wherein said noise generator generates a signal with a distribution function for which the kurtosis is different than the kurtosis of a Gaussian distribution function.

5. The communication device of claim 1 wherein said filter is a spectral limiting filter.

6. The communication device of claim 1 wherein said filter is selected from the group consisting of an autoregressive filter, an infinite impulse response filter combined with a low pass filter, and a finite impulse response filter with a moving average.

7. The communication device of claim 1 wherein said characteristic is from the group consisting of frequency, waveform, matrix pencil eigenvalue, phase noise, I/Q imbalance, timing jitter, phase jitter, symbol rate, pulse shape, a fourth-order statistic, relative rotational alignment of a signal constellation, power amplifier rise/fall time, and Doppler shift.

8. The communication device of claim 1 wherein said characteristic is a waveform from the group consisting of BPSK, QPSK, GMSK, QAM, DBPSK MFSK, FSK, and DQPSK waveforms.

9. The communication device of claim 1 wherein said characteristic is a waveform with a matrix pencil eigenvalue that is a function of the spatial second order moment of said waveform.

10. The communication device of claim 1 wherein said characteristic is a waveform with a matrix pencil eigenvalue that is a function of the spatial fourth order cumulant of said waveform.

11. The communication device of claim 1 wherein at least one of said plurality of signal sources is from the group consisting of an oscillator, a random signal generator, and a Laplacian noise generator.

12. The communication device of claim 1 wherein said combining means is a logic circuit.

13. The communication device of claim 1 wherein said combining means is from the group consisting of a mixer, a multiplier, a divider, and an adder.

14. The communication device of claim 1 wherein said communication signal has a received SNR less than 0 dB.

15. The communication device of claim 1 wherein said communication signal has a SNIR less than 0 dB at the intended receiver.

16. The communication device of claim 1 further comprising circuitry for forming symbols of an M-ary alphabet by assigning sequentially to each of said symbols a predetermined number of bits of said data signal.

17. The communication device of claim 16 wherein said predetermined number of bits is from the group consisting of positive integers.

18. The communication device of claim 16 wherein said communication signal is comprised of symbols of said M-ary alphabet.

19. The communication device of claim 18 wherein each of said symbols in said M-ary alphabet has a time duration unique among said alphabet.

20. The communication device of claim 19 wherein for each of said symbols said switch operatively connects one of said plural signal sources other than the signal source operatively connected for the immediately preceding symbol.

21. The communication device of claim 20 wherein said switch operatively connects one of said plural signal sources for the duration of the respective symbol.

22. The communication device of claim 1 wherein said first signal includes an I signal and a Q signal.

23. The communication device of claim 1 further comprising radio frequency processing circuitry for processing said communication signal for transmission.

24. The communication device of claim 23 further comprising a radio frequency transmitter and antenna for transmitting said communication signal.

25. A communication device for providing a communication signal from a sequence of bits comprising:

first means for providing a first signal;

second means for providing a second signal comprising, in sequence, as a function of said sequence of bits, one of a plurality of third signals each with a matrix pencil eigenvalue unique among said third signals; and

third means for combining said first and second signals to thereby provide the communication signal.

26. The communication device of claim 25 further comprising circuitry for forming symbols of an M-ary alphabet by assigning sequentially to each of said symbols a predetermined number of bits in said sequence of bits.

27. The communication device of claim 26 wherein said predetermined number of bits is from the group consisting of positive integers.

28. The communication device of claim 26 wherein said communication signal is comprised of symbols of said M-ary alphabet.

29. The communication device of claim 28 wherein each of said symbols in said M-ary alphabet has a time duration unique among said alphabet.

30. The communication device of claim 29 wherein said first means comprises a noise generator for providing a noise signal of which said first signal is a function thereof.

31. The communication device of claim 30 wherein said first means further comprises a filter for receiving said noise signal and producing therefrom a signal with temporal dependence between adjacent bits of said noise signal to thereby provide said first signal.

32. The communication device of claim 31 wherein said second means comprises a plurality of signal sources each providing one of said plurality of third signals.

33. The communication device of claim 32 wherein said second means further comprises a first switch for operatively connecting for each of said symbols one of said plural signal sources other than the signal source operatively connected for the immediately preceding symbol to thereby provide said second signal.

34. The communication device of claim 33 wherein said noise generator is a plurality of noise generators the outputs of which are operatively connected to a second switch which operates synchronously with said first switch to thereby provide said noise signal.

35. The communication device of claim 33 wherein said noise generator is a plurality of noise generators the outputs of which are operatively connected to a second switch which operates asynchronously with said first switch to thereby provide said noise signal.

36. The communication device of claim 33 wherein said filter is a plurality of filters the inputs of which are operatively connected to a second switch which receives said noise signal and which operates synchronously with said first switch to thereby provide said first signal.

37. The communication device of claim 33 wherein said filter is a plurality of filters the inputs of which are operatively connected to a second switch which receives said noise signal and which operates asynchronously with said first switch to thereby provide said first signal.

38. The communication device of claim 33 wherein said noise generator is a plurality of noise generators and said filter is a plurality of filters whereby each noise generator is operatively connected to one of said plurality of filters, wherein the outputs of said filters are operatively connected to a second switch which operates synchronously with said first switch to thereby provide said first signal.

39. The communication device of claim 33 wherein said noise generator is a plurality of noise generators and said filter is a plurality of filters whereby each noise generator is operatively connected to one of said plurality of filters, wherein the outputs of said filters are operatively connected to a second switch which operates asynchronously with said first switch to thereby provide said first signal.

40. The communication device of claim 29 wherein said first means comprises a signal source for providing said first signal.

41. The communication device of claim 40 wherein said second means comprises a plurality of noise generators each providing one of said plurality of third signals.

42. The communication device of claim 41 wherein said second means further comprises a first switch for operatively connecting for each of said symbols one of said plural noise generators other than the noise generator operatively connected for the immediately preceding symbol to thereby provide said second signal.

43. The communication device of claim 41 wherein each of said noise generators includes a filter for providing temporal dependence between immediately adjacent bits in the associated said third signal.

44. The communication device of claim 29 further comprising a filter for receiving said communication signal and producing therefrom a second communication signal with temporal dependence between adjacent symbols of said second communication signal.

45. The communication device of claim 29 wherein said first signal comprises a noise signal with a Laplacian distribution with temporal dependence between adjacent bits of said noise signal.

46. The communication device of claim 29 wherein said first signal comprises a noise signal with temporal dependence between adjacent bits of said noise signal and with a distribution function for which the kurtosis is greater than the kurtosis of a Gaussian distribution function.

47. The communication device of claim 29 wherein said first signal comprises a noise signal with temporal dependence between adjacent bits of said noise signal and with a distribution function for which the kurtosis is different than the kurtosis of a Gaussian distribution function.

48. In a receiver including an antenna with a plurality of antenna elements for receiving a communication signal comprised of a plurality of symbols and a digitizer for providing a bit stream from the received symbols, the improvement comprising a filter for generating a temporal dependence between immediately adjacent bits of said bit stream.

49. The receiver of claim 48 wherein the improvement further comprises means for determining a matrix pencil eigenvalue for at least one of said symbols.

50. The receiver of claim 49 wherein the improvement further comprises means for determining the generalized eigenvalue decomposition of said matrix pencil eigenvalue.

51. The receiver of claim 50 wherein the improvement further comprises means for determining the duration of said matrix pencil eigenvalue.

52. The receiver of claim 51 wherein the improvement further comprises means for filtering said symbols as a function of the determined duration of the associated matrix pencil eigenvalue.

53. The receiver of claim 52 wherein the improvement further comprises means for spatially correlating the filtered matrix pencil eigenvalues.

54. The receiver of claim 53 wherein the improvement further comprises means for sequentially mapping the correlated matrix pencil eigenvalues.

55. A communication system comprising a transmitter and a receiver geographically separated from the transmitter for communicating a communication signal formed from a sequence of bits wherein said communication signal is comprised of a plurality of symbols, comprising:

a transmitter comprising;

first means for providing a first signal;

second means for providing a second signal comprising in sequence as a function of said sequence of bits one of a plurality of third signals each with a matrix pencil eigenvalue unique among said third signals;

third means for combining said first and second signals to thereby provide said communication signal; and

transmitting means for transmitting said communication signal; and

a receiver comprising;

receiving means for receiving and digitizing the symbols of said communication signal to thereby produce a first received signal;

means for determining a matrix pencil eigenvalue for at least one of said first received signal symbols;

means for determining the generalized eigenvalue decomposition of said matrix pencil eigenvalue;

means for determining the duration of said matrix pencil eigenvalue;

[ditto]

means for filtering said symbols as a function of the determined duration of the associated matrix pencil eigenvalue;

[ditto]

means for spatially correlating the filtered matrix pencil eigenvalues; and

means for sequentially mapping the correlated matrix pencil eigenvalues to thereby determine at the receiver the sequence of bits in the communication signal.

56. The communication system of claim 55 further comprising at the receiver means for determining a spatial variable of said matrix pencil eigenvalue.

57. The communication system of claim 56 wherein said spatial variable is a steering vector.

58. The communication system of claim 57 further comprising at the receiver means for determining the angle of arrival of the communication signal as a function of said steering vector.

59. The communication system of claim 58 further comprising at the receiver means for determining the geolocation of said transmitter as a function of said steering vector.

60. A communication system comprising a transmitter and a receiver geographically separated from the transmitter for communicating a communication signal formed from a sequence of bits wherein said communication signal is comprised of a plurality of symbols, comprising:

a transmitter comprising;

first means for providing a first signal;

second means for providing a second signal comprising in sequence as a function of said sequence of bits one of a plurality of third signals each with a matrix pencil eigenvalue unique among said third signals;

third means for combining said first and second signals to thereby provide said communication signal; and

transmitting means for transmitting said communication signal; and

a receiver comprising;

receiving means for receiving and digitizing the symbols of said communication signal to thereby produce a first received signal;

means for determining a matrix pencil eigenvalue for at least one of said first received signal symbols;

means for determining the generalized eigenvalue decomposition of said matrix pencil eigenvalue;

means for determining the duration of said matrix pencil eigenvalue;

means for filtering said symbols as a function of the determined duration of the associated matrix pencil eigenvalue;

means for sorting the filtered matrix pencil eigenvalues into at least one group of like eigenvalues; and

means for sequentially mapping the correlated matrix pencil eigenvalues to thereby determine at the receiver the sequence of bits in the communication signal.

61. A method for providing a communication signal from a data signal comprised of a sequence of bits, comprising the steps of:

providing a first signal comprised of a bit stream;

receiving said first signal and generating a temporal dependence between immediately adjacent bits in said first signal to thereby provide a third signal;

providing a plurality of signal sources each providing a source signal with a characteristic unique from the others;

providing a combining means;

selectively operatively connecting as a function of said data signal one of said plurality of signal sources in sequence to said combining means to thereby provide a second signal; and

combining at said combining means said third signal with said second signal to thereby provide the communication signal from said data signal.

62. The method of claim 61 wherein said first signal has a Laplacian distribution function.

63. The method of claim 61 wherein said first signal has a distribution function for which the kurtosis is greater than the kurtosis of a Gaussian distribution function.

64. The method of claim 61 wherein said first signal has a distribution function for which the kurtosis is different than the kurtosis of a Gaussian distribution function.

65. The method of claim 61 wherein said characteristic is from the group consisting of frequency, waveform, matrix pencil eigenvalue, phase noise, I/Q imbalance, timing jitter, phase jitter, symbol rate, pulse shape, a fourth-order statistic, relative rotational alignment of a signal constellation, power amplifier rise/fall time, and Doppler shift.

66. The method of claim 61 wherein said characteristic is a waveform from the group consisting of BPSK, QPSK, GMSK, QAM, DBPSK MFSK, FSK, and DQPSK waveforms.

67. The method of claim 61 wherein said characteristic is a waveform with a matrix pencil eigenvalue that is a function of the spatial second order moment of said waveform.

68. The method of claim 61 wherein said characteristic is a waveform with a matrix pencil eigenvalue that is a function of the spatial fourth order cumulant of said waveform.

69. The method of claim 61 wherein said communication signal has a received SNR less than 0 dB.

70. The method of claim 61 wherein said communication signal has a SNIR less than 0 dB at the intended receiver.

71. The method of claim 61 further comprising the step of forming symbols of an M-ary alphabet by assigning sequentially to each of said symbols a predetermined number of bits of said data signal.

72. The method of claim 71 wherein said predetermined number of bits is from the group consisting of positive integers.

73. The method of claim 71 wherein said communication signal is comprised of symbols of said M-ary alphabet.

74. The method of claim 73 wherein each of said symbols in said M-ary alphabet has a time duration unique among said alphabet.

75. The method of claim 74 wherein for each of said symbols the step of selectively operatively connecting is accomplished so that one of said plural signal sources other than the signal source for the immediately preceding symbol is operatively connected.

76. The method of claim 75 wherein the step of selectively operatively connecting is accomplished such that one of said plural signal sources is operatively connected for the duration of the respective symbol.

77. The method of claim 71 wherein said first signal includes an in-phase signal and a quadrature signal.

78. The method of claim 71 further comprising the step of processing said communication signal for radio frequency transmission.

79. The method of claim 78 further comprising the step of transmitting said communication signal.

80. A method for providing a communication signal from a sequence of bits comprising:

providing a first signal;

providing a second signal comprising, in sequence, as a function of said sequence of bits, one of a plurality of third signals each with a matrix pencil eigenvalue unique among said third signals; and

combining said first and second signals to thereby provide the communication signal.

81. The method of claim 80 further comprising the step of forming symbols of an M-ary alphabet by assigning sequentially to each of said symbols a predetermined number of bits in said sequence of bits.

82. The method of claim 81 wherein said predetermined number of bits is from the group consisting of positive integers.

83. The method of claim 81 wherein said communication signal is comprised of symbols of said M-ary alphabet.

84. The method of claim 83 wherein each of said symbols in said M-ary alphabet has a time duration unique among said alphabet.

85. The method of claim 84 wherein said first signal is comprised of a noise signal of which said first signal is a function thereof.

86. The method of claim 85 wherein said noise signal is produced with temporal dependence between adjacent bits to thereby provide said first signal.

87. The method of claim 86 wherein said second signal is comprised of a sequential combination of a plurality of third signals provided by a corresponding plurality of signal sources.

88. The method of claim 87 wherein the step of providing said second signal is accomplished by operatively connecting said third signals to a first switch whereby for each of said symbols said switch operatively connects one of said third signals other than the third signal that was operatively connected for the preceding symbol.

89. The method of claim 88 wherein said noise signal is a plurality of noise signals which are operatively connected to a second switch which operates synchronously with said first switch to thereby provide said noise signal.

90. The method of claim 88 wherein said noise signal is a plurality of noise signals which are operatively connected to a second switch which operates asynchronously with said first switch to thereby provide said noise signal.

91. The method of claim 88 wherein said temporal dependence between adjacent bits of said noise signal is provided by a plurality of filters arranged in parallel the inputs of which are operatively connected to a second switch which receives said noise signal and which operates synchronously with said first switch to sequentially operatively connect one of said plurality of filters to thereby provide said first signal.

92. The method of claim 88 wherein said temporal dependence between adjacent bits of said noise signal is provided by a plurality of filters arranged in parallel the inputs of which are operatively connected to a second switch which receives said noise signal and which operates asynchronously with said first switch to sequentially operatively connect one of said plurality of filters to thereby provide said first signal.

93. The method of claim 88 wherein said noise signal is a plurality of noise signals and said temporal dependence between adjacent bits of said noise signal is provided by a corresponding plurality of filters arranged in parallel whereby each said noise signal is operatively connected to one of said plurality of filters wherein the outputs of said filters are operatively connected to a second switch which operates synchronously with said first switch to thereby provide said first signal.

94. The method of claim 88 wherein said noise signal is a plurality of noise signals and said temporal dependence between adjacent bits of said noise signal is provided by a corresponding plurality of filters arranged in parallel whereby each said noise signal is operatively connected to one of said plurality of filters wherein the outputs of said filters are operatively connected to a second switch which operates asynchronously with said first switch to thereby provide said first signal.

95. The method of claim 84 wherein said first signal is provided by a signal source.

96. The method of claim 95 wherein said second signal is provided by a first switch for operatively connecting for each of said symbols one of said third signals other than the noise signal operatively connected for the immediately preceding symbol.

97. The method of claim 96 wherein for each of said third signals the unique matrix pencil eigenvalue is a function of the temporal dependence between immediately adjacent bits provided by a filter.

98. The method of claim 84 further comprising the step of providing temporal dependence between adjacent bits of said communication signal and producing therefrom a second communication signal.

99. The method of claim 98 wherein the temporal dependence is provided by a filter.

100. The method of claim 84 wherein said first signal comprises a noise signal with a Laplacian distribution with temporal dependence between adjacent bits of said noise signal.

101. The method of claim 84 wherein said first signal comprises a noise signal with temporal dependence between adjacent bits of said noise signal and with a distribution function for which the kurtosis is greater than the kurtosis of a Gaussian distribution function.

102. The method of claim 84 wherein said first signal comprises a noise signal with temporal dependence between adjacent bits of said noise signal and with a distribution function for which the kurtosis is different than the kurtosis of a Gaussian distribution function.

103. In a method of receiving a communication signal comprised of a plurality of symbols in a receiver including an antenna with a plurality of antenna elements and a digitizer for providing a bit stream from the received symbols, the improvement comprising the step of providing a temporal dependence between immediately adjacent bits of said bit stream.

104. The method of claim 103 wherein the improvement further comprises the step of determining a matrix pencil eigenvalue for at least one of said symbols.

105. The method of claim 104 wherein the improvement further comprises the step of determining the generalized eigenvalue decomposition of said matrix pencil eigenvalue.

106. The method of claim 105 wherein the improvement further comprises the step of determining the duration of said matrix pencil eigenvalue.

107. The method of claim 106 wherein the improvement further comprises the step of filtering said symbols as a function of the determined duration of the associated matrix pencil eigenvalue.

108. The method of claim 107 wherein the improvement further comprises the step of spatially correlating the filtered matrix pencil eigenvalues.

109. The method of claim 108 wherein the improvement further comprises the step of sequentially mapping the correlated matrix pencil eigenvalues.

110. A method of communicating between a transmitter and a receiver including a multi-element array antenna which is geographically spaced apart from said transmitter a communication signal formed from a sequence of bits wherein said communication signal is comprised of a plurality of symbols, comprising the steps of:

in the transmitter;

providing a first signal;

providing a second signal comprising in sequence as a function of said sequence of bits one of a plurality of third signals each with a matrix pencil eigenvalue unique among said third signals;

combining said first and second signals to thereby provide said communication signal; and

transmitting said communication signal; and

in the receiver;

receiving and digitizing the symbols of said communication signal to thereby produce a first received signal;

determining a matrix pencil eigenvalue for at least one of said first received signal symbols;

determining the generalized eigenvalue decomposition of said matrix pencil eigenvalue;

determining the duration of said matrix pencil eigenvalue;

filtering said symbols as a function of the determined duration of the associated matrix pencil eigenvalue;

spatially correlating the filtered matrix pencil eigenvalues; and

sequentially mapping the correlated matrix pencil eigenvalues to thereby determine at the receiver the sequence of bits in the communication signal.

111. The method of claim 110 wherein the step of determining the matrix pencil eigenvalue for a received symbol includes the step of determining a spatial second-order moment.

112. The method of claim 110 wherein the step of determining the matrix pencil eigenvalue for a received symbol includes the step of determining a spatial fourth-order cumulant.

113. The method of claim 110 further comprising the step of determining a spatial variable of said matrix pencil eigenvalue.

114. The method of claim 113 wherein said spatial variable is a steering vector of the communication signal.

115. The method of claim 114 further comprising at the receiver the step of determining the angle of arrival of the communication signal as a function of said steering vector.

116. The method of claim 114 further comprising at the receiver the step of determining the geolocation of said transmitter as a function of said steering vector.

117. The method of claim 110 wherein said first signal is a noise signal comprised of a bit stream with a Laplacian distribution with temporal dependence between immediately adjacent bits.

118. The method of claim 110 wherein each of said third signals has a unique frequency among said third signals.

119. The method of claim 110 wherein each of said third signals has a unique waveform among said third signals.

120. The method of claim 119 wherein said waveforms are from the group consisting of BPSK, QPSK, GMSK, QAM, DBPSK MFSK, FSK, and DQPSK waveforms.

121. The method of claim 119 further comprising the step of modulating the waveform of at least one of said third signals with random data at a rate substantially exceeding the rate of said sequence of bits.

122. The method of claim 119 further comprising the step of modulating the waveform of at least one of said third signals with data from a third communication signal.

123. The method of claim 110 wherein the step of receiving and digitizing includes the step of organizing the digitized bits into blocks of data comprised of sequential snapshots wherein said snapshots are each comprised of a bit from each element of said multi-element array antenna

124. The method of claim 123 wherein the matrix pencil eigenvalue is determined from said blocks of data.

125. The method of claim 124 wherein said block of data includes approximately 5000 snapshots.

126. The method of claim 125 wherein said duration of matrix pencil eigenvalues is the number of sequential blocks of data with approximately the same matrix pencil eigenvalue.

127. The method of claim 110 wherein the communication signal has a received SNR less than 0 dB.

128. The method of claim 110 wherein the communication signal has a SNIR less than 0 dB at the receiver.

129. The method of claim 110 wherein the communication signal has a SNIR less than −

6 dB at the receiver.

130. The method of claim 110 wherein said sequence of third signals is determined at random.

131. The method of claim 110 wherein said sequence of third signals is predetermined.

132. A method of communicating between a transmitter and a receiver including a multi-element array antenna which is geographically spaced apart from said transmitter a communication signal formed from a sequence of bits wherein said communication signal is comprised of a plurality of symbols, comprising the steps of:

in the transmitter;

providing a first signal;

providing a second signal comprising in sequence as a function of said sequence of bits one of a plurality of third signals each with a matrix pencil eigenvalue unique among said third signals;

combining said first and second signals to thereby provide said communication signal; and

transmitting said communication signal; and

in the receiver;

receiving and digitizing the symbols of said communication signal to thereby produce a first received signal;

determining a matrix pencil eigenvalue for at least one of said first received signal symbols;

determining the generalized eigenvalue decomposition of said matrix pencil eigenvalue;

determining the duration of said matrix pencil eigenvalue;

filtering said symbols as a function of the determined duration of the associated matrix pencil eigenvalue;

sorting the filtered matrix pencil eigenvalues into at least one group of like eigenvalues; and

sequentially mapping the correlated matrix pencil eigenvalues to thereby determine at the receiver the sequence of bits in the communication signal.

133. A method of communicating information comprised of a sequence of bits from a transmitter to a receiver comprising the steps of:

modulating a carrier wave with a data signal to thereby produce a first signal wherein the data signal does not represent the information to be communicated;

transmitting the first signal from the transmitter;

receiving the first signal at the receiver;

determining at the receiver the communicated information independently of the data signal.

134. The method of claim 133 wherein the step of determining the communicated information is performed without demodulating the first signal.

135. The method of claim 133 further comprising the step of providing a second signal with temporal dependence between immediately adjacent bits and combining said second signal with said modulated carrier wave to thereby produce said first signal.

136. The method of claim 135 further comprising the steps of:

sequentially grouping a predetermined number of bits in said sequence of bits into symbols to thereby provide symbols of an M-ary alphabet;

providing a plurality of third signals each with a matrix pencil eigenvalue unique among said third signals;

providing a switch whereby for each of said symbols said switch operatively connects one of said third signals other than the third signal that was operatively connected for the preceding symbol to thereby form said second signal.

137. The method of claim 136 wherein each of said symbols in said M-ary alphabet has a time duration unique among said alphabet.

138. The method of claim 137 wherein said information is communicated to the receiver as a function of the durations of said symbols in said M-ary alphabet.

139. In a method of communicating information from a transmitter to a receiver using a communication signal comprised of a carrier wave modulated by a data signal, the improvement comprising determining the information at the receiver independent of the data signal.

140. In a method of communicating information from a transmitter to a receiver using a communication signal containing a plurality of symbols comprised of a carrier wave modulated by a data signal, the improvement comprising determining the information at the receiver as a function of a higher-order statistic of the received symbols.

141. The method of claim 140 wherein said symbols comprise an M-ary alphabet and said higher-order statistic for each symbol in the M-ary alphabet is unique among said alphabet.

142. The method of claim 140 wherein said information includes a spatial variable.

143. In a method of communicating a first information stream from a transmitter to a receiver using a communication signal containing a plurality of symbols comprised of a carrier wave modulated by a data signal, the improvement comprising communicating a second information stream from the transmitter to the receiver by selectively altering a characteristic of said communication signal wherein said second information stream is different than said first information stream.

144. The method of claim 143 wherein said characteristic is from the group consisting of frequency, waveform, matrix pencil eigenvalue, phase noise, I/Q imbalance, timing jitter, phase jitter, symbol rate, pulse shape, a fourth-order statistic, relative rotational alignment of a signal constellation, power amplifier rise/fall time, and Doppler shift.

145. In a method of communication using plural waveforms where the duration of the transmission of each waveform represents a symbol, the improvement wherein the duration of transmission is determined by the state of a high-order statistic of a characteristic of the waveforms.

146. The method of claim 145 wherein said high-order statistic is a spatial second-order moment.

147. The method of claim 145 wherein said high-order statistic is a spatial fourth-order cumulant.

148. A method for communication of a message comprising a plurality of sequenced M-ary alphabet symbols, said method comprising the steps of:

assigning each M-ary alphabet symbol a unique symbol duration;

generating a waveform for which both the spatial 2nd order moment or the spatial 4^th order cumulant are constant and not zero; and

for each symbol, transmitting the waveform for the assigned symbol duration immediately followed by a pause in waveform transmission.

149. A method for communication of a message comprising a plurality of sequenced M-ary alphabet symbols, said method comprising the steps of:

assigning each M-ary alphabet symbol a unique symbol duration;

generating plural waveforms for which the spatial 2nd order moment and the spatial 4^th order cumulant are constant, nonzero, and unique; and

for each symbol, transmitting one of the plural waveforms for the assigned symbol duration so that immediately adjacent symbols are transmitted by different waveforms.

150. A method for communicating a message comprising a plurality of sequenced M-ary alphabet symbols represented by M-ary durations, said method comprising the steps of:

receiving a signal in a multiple element array;

determining a high order statistic of a signal characteristic of each symbol, and determining the duration of each symbol by the state of the determined high order statistic.