US4943974A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Detection of burst signal transmissions
Assignee: Comsat Corp
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Filing: 1988-10-21
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Granted: 1990-07-24
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Expires: 2008-10-21
Abstract
Abstract A method is disclosed for detecting the presence of and synchronizing to burst transmissions which contain repeated acquisition codes. The received signal is applied as an input to a surface acoustic wave (SAW) filter which is matched to detect one repetition of the code. The SAW filter correlation output is sampled at times corresponding to the times of arrival of each repetition of the code. The mean value and variance of the correlation values for each repetition are computed, and the system declares an acquisition when the mean value and variance meet certain criteria.
Inventors
- 👤 Masoud Motamedi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:23
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/69; H04B1/707; H04B1/7073; H04B1/7075; H04B1/70751; H04B1/70753; G; G01; G01S; G01S13/00; G01S13/87; G01S13/878; H04B2201/00; H04B2201/69; H04B2201/707; H04B2201/70707; H04B2201/70709
Claims Analysis
Total Claims: 75
Claim 1
Independent Claim
165 words
A method for detecting a burst signal transmission containing a sequence of N acquisition codes occurring at known time intervals, comprising: receiving said burst signal transmission and comparing successively received portions thereof to a stored acquisition code pattern; generating a time-varying correlation output having a magnitude proportional to the similarity between the successively received portions of the burst signal transmission and the stored acquisition code pattern; detecting and measuring peaks in the magnitude of said correlation output; forming a group of N peak magnitudes occurring at time intervals corresponding to said known time intervals; computing values proportional to the mean value and variance, respectively, of the group of N peak magnitudes; comparing the computed values proportional to the mean value and variance to predetermined minimum and maximum values, respectively; and indicating the presence of a burst signal transmission when the computed value proportional to the mean value exceeds said minimum value and the computed value proportional to the variance is less than said maximum value.
Claim 2
Independent Claim
165 words
A method for detecting a burst signal transmission containing a sequence of N acquisition codes occurring at known time intervals, comprising: receiving said burst signal transmission and comparing successively received portions thereof to a stored acquisition code pattern; generating a time-varying correlation output having a magnitude proportional to the similarity between the successively received portions of the burst signal transmission and the stored acquisition code pattern; detecting and measuring peaks in the magnitude of said correlation output; forming a group of N peak magnitudes occurring at time intervals corresponding to said known time intervals; computing values proportional to the mean value and variance, respectively, of the group of N peak magnitudes; comparing the computed values proportional to the mean value and variance to predetermined minimum and maximum values, respectively; and indicating the presence of a burst signal transmission when the computed value proportional to the mean value exceeds said minimum value and the computed value proportional to the variance is less than said maximum value.
Claim 3
Dependent Claim
14 words
The method of claim 1, wherein said acquisition codes are identical to each other.
Claim 4
Dependent Claim
15 words
The method of claim 1, wherein said known time intervals are equal to each other.
Claim 5
Dependent Claim
61 words
The method of claim 1, wherein said burst signal transmission comprises a digital bit stream modulated on a carrier frequency, and wherein the step of comparing successively received portions of the burst signal transmission to a stored acquisition code pattern is carried out by repeatedly comparing the most recently received bits of the burst signal transmission with stored aacquisition code bits.
Claim 6
Dependent Claim
16 words
The method of claim 1, wherein the burst signal transmission comprises a spread spectrum modulated signal.
Claim 7
Dependent Claim
18 words
The method of claim 5, wherein the burst signal transmission is modulated by a direct sequence pseudo-noise code.
Claim 8
Dependent Claim
38 words
The method of claim 1, wherein said burst signal transmission contains data following said sequence of N acquisition codes, and further comprising the step of demodulating said data following an indication that a burst signal transmission is present.
Claim 9
Independent Claim
207 words
A method for detecting first and second burst signal transmissions arriving in an overlapping manner, each transmission containing a sequence of N acquisition codes occurring at known time intervals, comprising: receiving each of said first and second burst signal transmissions and comparing successively received portions of each burst signal transmission to a stored acquisition code pattern; generating a time-varying correlation output having a magnitude proportional to the similarity between the successively received portions of each burst signal transmission and the stored acquisition code pattern; detecting and measuring peaks in the magnitude of said correlation output; forming first and second groups of N peak magnitudes, the peak magnitudes of each group occurring at time intervals corresponding to said known time intervals; computing values proportional to the mean value and variance, respectively, of each such group of N peak magnitudes; comparing the computed values proportional to the mean value and variance of each group to predetermined minimum and maximum values, respectively; and indicating the presence of each of said first and second burst signal transmissions when the computed value proportional to the mean value of the corresponding group exceeds said minimum value and the computed value proportional to the variance of said group is less than said maximum value.
Claim 10
Independent Claim
207 words
A method for detecting first and second burst signal transmissions arriving in an overlapping manner, each transmission containing a sequence of N acquisition codes occurring at known time intervals, comprising: receiving each of said first and second burst signal transmissions and comparing successively received portions of each burst signal transmission to a stored acquisition code pattern; generating a time-varying correlation output having a magnitude proportional to the similarity between the successively received portions of each burst signal transmission and the stored acquisition code pattern; detecting and measuring peaks in the magnitude of said correlation output; forming first and second groups of N peak magnitudes, the peak magnitudes of each group occurring at time intervals corresponding to said known time intervals; computing values proportional to the mean value and variance, respectively, of each such group of N peak magnitudes; comparing the computed values proportional to the mean value and variance of each group to predetermined minimum and maximum values, respectively; and indicating the presence of each of said first and second burst signal transmissions when the computed value proportional to the mean value of the corresponding group exceeds said minimum value and the computed value proportional to the variance of said group is less than said maximum value.
Claim 11
Dependent Claim
31 words
The method of claim 8, wherein the acquisition codes of each of said first and second transmissions are identical to each other and to the acquisition codes of the other transmission.
Claim 12
Dependent Claim
33 words
The method of claim 8, wherein the known time intervals of each of said first and second transmissions are equal to each other and to the known time intervals of the other transmission.
Claim 13
Dependent Claim
22 words
The method of claim 8, wherein the predetermined minimum and maximum values are the same for each group of N peak magnitudes.
Claim 14
Dependent Claim
58 words
The method of claim 8, wherein said burst transmissions comprise digital bit streams modulated on a carrier frequency, and wherein the step of comparing successively received portions of each burst signal transmission to a stored acquisition code pattern is carried out by repeatedly comparing the most recently received bits of the received signal with stored acquisition code bits.
Claim 15
Dependent Claim
18 words
The method of claim 8, wherein the first and second burst signal transmissions comprise spread spectrum modulated signals.
Claim 16
Dependent Claim
21 words
The method of claim 13, wherein the first and second burst signal transmissions are modulated by a direct sequence pseudo-noise code.
Claim 17
Dependent Claim
48 words
The method of claim 8, wherein each of said first and second burst signal transmissions contains data following said sequence of N acquisition codes, and further comprising the step of demodulating said data following an indication that each of said first and second burst signal transmissions is present.
Claim 18
Independent Claim
169 words
A method for transmitting and receiving burst mode signals, comprising: transmitting a burst signal containing a sequence of N acquisition codes occurring at predetermined time intervals; receiving said burst signal transmission and comparing successively received portions thereof to a stored acquisition code pattern; generating a time-varying correlation output having a magnitude proportional to the similarity between successively received portions of the burst signal transmission and the stored acquisition code pattern; detecting and measuring peaks in the magnitude of said correlation output; forming a group of N peak magnitudes occurring at time intervals corresponding to said predetermined time intervals; computing values proportional to the mean value and variance, respectively, of the group of N peak magnitudes; comparing the computed values proportional to the mean value and variance to predetermined minimum and maximum values, respectively; and indicating the presence of a burst signal transmission when the computed value proportional to the mean value exceeds said minimum value and the computed value proportional to the variance is less than said maximum value.
Claim 19
Independent Claim
169 words
A method for transmitting and receiving burst mode signals, comprising: transmitting a burst signal containing a sequence of N acquisition codes occurring at predetermined time intervals; receiving said burst signal transmission and comparing successively received portions thereof to a stored acquisition code pattern; generating a time-varying correlation output having a magnitude proportional to the similarity between successively received portions of the burst signal transmission and the stored acquisition code pattern; detecting and measuring peaks in the magnitude of said correlation output; forming a group of N peak magnitudes occurring at time intervals corresponding to said predetermined time intervals; computing values proportional to the mean value and variance, respectively, of the group of N peak magnitudes; comparing the computed values proportional to the mean value and variance to predetermined minimum and maximum values, respectively; and indicating the presence of a burst signal transmission when the computed value proportional to the mean value exceeds said minimum value and the computed value proportional to the variance is less than said maximum value.
Claim 20
Dependent Claim
14 words
The method of claim 16, wherein said acquisition codes are identical to each other.
Claim 21
Dependent Claim
15 words
The method of claim 16, wherein said known time intervals are equal to each other.
Claim 22
Dependent Claim
61 words
The method of claim 16, wherein said burst signal transmission comprises a digital bit stream modulated on a carrier frequency, and wherein the step of comparing successively received portions of the burst signal transmission to a stored acquisition code pattern is carried out by repeatedly comparing the most recently received bits of the burst signal transmission with stored acquisition code bits.
Claim 23
Dependent Claim
16 words
The method of claim 16, wherein the burst signal transmission comprises a spread spectrum modulated signal.
Claim 24
Dependent Claim
18 words
The method of claim 20, wherein the burst signal transmission is modulated by a direct sequence pseudo-noise code.
Claim 25
Dependent Claim
38 words
The method of claim 16, wherein said burst signal transmission contains data following said sequence of N acquisition codes, and further comprising the step of demodulating said data following an indication that a burst signal transmission is present.
Claim 26
Independent Claim
214 words
A method for transmitting first and second burst signals and for receiving said signals in an overlapping manner, comprising: transmitting first and second burst signals, each containing a sequence of N acquisition codes occurring at predetermined time intervals; receiving each of said first and second burst signal transmissions and comparing successively received portions of each burst signal transmission to a stored acquisition code pattern; generating a time-varying correlation output having a magnitude proportional to the similarity between successively received portions of each burst signal transmission and the stored acquisition code pattern; detecting and measuring peaks in the magnitude of said correlation output; forming first and second groups of N peak magnitudes, the peak magnitudes of each group occurring at time intervals corresponding to said predetermined time intervals; computing values proportional to the mean value and variance, respectively, of each such group of N peak magnitudes; comparing the computed values proportional to the mean value and variance of each group to predetermined minimum and maximum values, respectively; and indicating the presence of each of said first and second burst signal transmissions when the computed value proportional to the mean value of the corresponding group exceeds said minimum value and the computed value proportional to the variance of said group is less than said maximum value.
Claim 27
Independent Claim
214 words
A method for transmitting first and second burst signals and for receiving said signals in an overlapping manner, comprising: transmitting first and second burst signals, each containing a sequence of N acquisition codes occurring at predetermined time intervals; receiving each of said first and second burst signal transmissions and comparing successively received portions of each burst signal transmission to a stored acquisition code pattern; generating a time-varying correlation output having a magnitude proportional to the similarity between successively received portions of each burst signal transmission and the stored acquisition code pattern; detecting and measuring peaks in the magnitude of said correlation output; forming first and second groups of N peak magnitudes, the peak magnitudes of each group occurring at time intervals corresponding to said predetermined time intervals; computing values proportional to the mean value and variance, respectively, of each such group of N peak magnitudes; comparing the computed values proportional to the mean value and variance of each group to predetermined minimum and maximum values, respectively; and indicating the presence of each of said first and second burst signal transmissions when the computed value proportional to the mean value of the corresponding group exceeds said minimum value and the computed value proportional to the variance of said group is less than said maximum value.
Claim 28
Dependent Claim
31 words
The method of claim 23, wherein the acquisition codes of each of said first and second transmissions are identical to each other and to the acquisition codes of the other transmission.
Claim 29
Dependent Claim
33 words
The method of claim 23, wherein the predetermined time intervals of each of said first and second transmissions are equal to each other and to the predetermined time intervals of the other transmission.
Claim 30
Dependent Claim
22 words
The method of claim 23, wherein the predetermined minimum and maximum values are the same for each group of N peak magnitudes.
Claim 31
Dependent Claim
58 words
The method of claim 23, wherein said burst transmissions comprise digital bit streams modulated on a carrier frequency, and wherein the step of comparing successively received portions of each burst signal transmission to a stored acquisition code pattern is carried out by repeatedly comparing the most recently received bits of the received signal with stored acquisition code bits.
Claim 32
Dependent Claim
18 words
The method of claim 23, wherein the first and second burst signal transmissions comprise spread spectrum modulated signals.
Claim 33
Dependent Claim
21 words
The method of claim 28, wherein the first and second burst signal transmissions are modulated by a direct sequence pseudo-noise code.
Claim 34
Dependent Claim
48 words
The method of claim 23, wherein each of said first and second burst signal transmissions contains data following said sequence of N acquisition codes, and further comprising the step of demodulating said data following an indication that each of said first and second burst signal transmissions is present.
Claim 35
Dependent Claim
177 words
An acquisition circuit for detecting a burst signal transmission containing a sequence of N acquisition codes occurring at known time intervals, comprising: first means for generating a correlation output having a magnitude proportional to the similarity between successively received portions of the burst signal transmission and a stored acquisition code pattern; second means coupled to said first means for detecting and measuring peaks in the magnitude of said correlation output; third means coupled to said second means for forming a group of N peak magnitudes occurring at time intervals corresponding to said known time intervals, and for computing values proportional to the mean value and variance, respectively, of said group of N peak magnitudes; fourth means coupled to said third means for comparing the computed values proportional to the mean value and variance to predetermined minimum and maximum values, respectively, and for indicating the presence of a burst signal transmission when the computed value proportional to the mean value exceeds said minimum value and the computed value proportional to the variance is less than said maximum value.
Claim 36
Dependent Claim
177 words
An acquisition circuit for detecting a burst signal transmission containing a sequence of N acquisition codes occurring at known time intervals, comprising: first means for generating a correlation output having a magnitude proportional to the similarity between successively received portions of the burst signal transmission and a stored acquisition code pattern; second means coupled to said first means for detecting and measuring peaks in the magnitude of said correlation output; third means coupled to said second means for forming a group of N peak magnitudes occurring at time intervals corresponding to said known time intervals, and for computing values proportional to the mean value and variance, respectively, of said group of N peak magnitudes; fourth means coupled to said third means for comparing the computed values proportional to the mean value and variance to predetermined minimum and maximum values, respectively, and for indicating the presence of a burst signal transmission when the computed value proportional to the mean value exceeds said minimum value and the computed value proportional to the variance is less than said maximum value.
Claim 37
Dependent Claim
15 words
The acquisition circuit of claim 31 wherein said acquisition codes are identical to each other.
Claim 38
Dependent Claim
16 words
The acquisition circuit of claim 31, wherein said known time intervals are equal to each other.
Claim 39
Dependent Claim
45 words
The acquisition circuit of claim 31, wherein said burst signal transmission comprises a digital bit stream modulated on a carrier frequency, and wherein said first means comprises means for repeatedly comparing the most recently received bits of the received signal with stored acquisition cod bits.
Claim 40
Dependent Claim
55 words
The acquisition circuit of claim 31, wherein said first means comprises: a matched surface acoustic wave filter having an input to which the received signal is applied and an output; and an envelope detector having an input connected to the output of the surface acoustic wave filter and an output connected to said second means.
Claim 41
Dependent Claim
68 words
The acquisition circuit of claim 35, wherein said second means comprises: a peak detector having an input coupled to the output of said envelope detector and an output; and an analog-to-digital converter having an analog signal input coupled to the output of said envelope detector, an enable input coupled to the output of the peak detector, and a digital output coupled to the input of said third means.
Claim 42
Dependent Claim
63 words
The acquisition circuit of claim 36, wherein said third means comprises a storage and calculation circuit having a digital input coupled to the digital output of the analog-to-digital converter, an enable input coupled to the output of the peak detector, and first and second digital outputs for providing the computed values proportional to the mean value and variance, respectively, to said fourth means.
Claim 43
Dependent Claim
194 words
The acquisition circuit of claim 37, wherein said storage and calculation circuit comprises first and second circuit paths, each of said circuit paths having an input coupled to the digital input of the storage and calculation circuit, an output, and a series of N-1 delay stages between said input and said output, each delay stage comprising: a clocked first-in-first-out (FIFO) register having an input and an output, said FIFO register having a length sufficient to provide a delay equal to the known interval between successive acquisition codes; and an adder having a first input coupled to the output of the FIFO register, a second input coupled to the digital input of the storage and calculation circuit, and an output; said delay stages being connected in a manner such that the FIFO register of the first delay stage has its input coupled to the digital input of the storage and calculation circuit, and the FIFO register of each succeeding delay stage has its input coupled to the output of the adder in the immediately preceding delay stage, the output of the adder in the last delay stage providing the output of the corresponding circuit path.
Claim 44
Dependent Claim
135 words
The acquisition circuit of claim 38, further comprising: a first squaring circuit and a multiply-by-N scalar circuit connected in series and interposed between the input of the second circuit path and the inputs of the FIFO register and adder of the first delay stage in the second circuit path; a second squaring circuit having an input coupled to the output of the first circuit path and an output; and a subtracter having a first input coupled to the output of the second circuit path, a second input coupled to the output of the second squaring circuit, and an output; wherein the output of the first circuit path provides the first digital output of the storage and calculation circuit and the output of the subtracter provides the second digital otuput of the storage and calculation circuit.
Claim 45
Dependent Claim
64 words
The acquisition circuit of claim 39, further comprising a latch circuit having a digital input coupled to the digital input of the storage and calculation circuit, a digital output coupled to the inputs of the first and second circuit paths, a set input coupled to the enable input of the storage and calculation circuit, and a reset input coupled to a clock signal source.
Claim 46
Dependent Claim
132 words
The acquisition circuit of claim 37, wherein said fourth means comprises: a first comparator having a first input coupled to the first digital output of the storage and calculation circuit, a second input, and an output; means for applying said predetermined minimum mean value to the second input of said first comparator; a second comparator having a first input coupled to the second digital output of the storage and calculation circuit, a second input, and an output; means for applying said predetermined maximum variance value to the second input of said second comparator; and an AND circuit having first and second inputs coupled to the outputs of the first and second comparators, respectively, and an output, the output of said AND circuit indicating the absence or presence of a burst signal transmission.
Claim 47
Dependent Claim
195 words
A receiver for receiving a burst signal transmission containing a sequence of N acquisition codes occurring at known time intervals and followed by data, said receiver comprising an acquisition circuit and a signal processing circuit, said acquisition circuit comprising: first means for generating a correlation output having a magnitude proportional to the similarity between successively received portions of the burst signal transmission and a stored acquisition code pattern; second means coupled to said first means for detecting and measuring peaks in the magnitude of said correlation output; third means coupled to said second means for forming a group of N peak magnitudes occurring at time intervals corresponding to said known time intervals, and for computing values proportional to the mean value and variance, respectively, of said group of N peak magnitudes; and fourth means coupled to said third means for comparing the computed values proportional to the mean value and variance to predetermined minimum and maximum values, respectively, and for indicating the presence of a burst signal transmission when the computed value proportional to the mean value exceeds said minimum value and the computed value proportional to the variance is less than said maximum value.
Claim 48
Dependent Claim
195 words
A receiver for receiving a burst signal transmission containing a sequence of N acquisition codes occurring at known time intervals and followed by data, said receiver comprising an acquisition circuit and a signal processing circuit, said acquisition circuit comprising: first means for generating a correlation output having a magnitude proportional to the similarity between successively received portions of the burst signal transmission and a stored acquisition code pattern; second means coupled to said first means for detecting and measuring peaks in the magnitude of said correlation output; third means coupled to said second means for forming a group of N peak magnitudes occurring at time intervals corresponding to said known time intervals, and for computing values proportional to the mean value and variance, respectively, of said group of N peak magnitudes; and fourth means coupled to said third means for comparing the computed values proportional to the mean value and variance to predetermined minimum and maximum values, respectively, and for indicating the presence of a burst signal transmission when the computed value proportional to the mean value exceeds said minimum value and the computed value proportional to the variance is less than said maximum value.
Claim 49
Dependent Claim
14 words
The receiver of claim 42 wherein said acquisition codes are identical to each other.
Claim 50
Dependent Claim
15 words
The receiver of claim 42, wherein said known time intervals are equal to each other.
Claim 51
Dependent Claim
44 words
The receiver of claim 42, wherein said burst signal transmission comprises a digital bit stream modulated on a carrier frequency, and wherein said first means comprises means for repeatedly comparing the most recently received bits of the received signal with stored acquisition code bits.
Claim 52
Dependent Claim
54 words
The receiver of claim 42, wherein said first means comprises: a matched surface acoustic wave filter having an input to which the received signal is applied and an output; and an envelope detector having an input connected to the output of the surface acoustic wave filter and an output connected to said second means.
Claim 53
Dependent Claim
67 words
The receiver of claim 46, wherein said second means comprises: a peak detector having an input coupled to the output of said envelope detector and an output; and an analog-to-digital converter having an analog signal input coupled to the output of said envelope detector, an enable input coupled to the output of the peak detector, and a digital output coupled to the input of said third means.
Claim 54
Dependent Claim
62 words
The receiver of claim 47, wherein said third means comprises a storage and calculation circuit having a digital input coupled to the digital output of the analog-to-digital converter, an enable input coupled to the output of the peak detector, and first and second digital outputs for providing the computed values proportional to the mean value and variance, respectively, to said fourth means.
Claim 55
Dependent Claim
193 words
The receiver of claim 48, wherein said storage and calculation circuit comprises first and second circuit paths, each of said circuit paths having an input coupled to the digital input of the storage and calculation circuit, an output, and a series of N-1 delay stages between said input and said output, each delay stage comprising: a clocked first-in-first-out (FIFO) register having an input and an output, said FIFO register having a length sufficient to provide a delay equal to the known interval between successive acquisition codes; and an adder having a first input coupled to the output of the FIFO register, a second input coupled to the digital input of the storage and calculation circuit, and an output; said delay stages being connected in a manner such that the FIFO register of the first delay stage has its input coupled to the digital input of the storage and calculation circuit, and the FIFO register of each succeeding delay stage has its input coupled to the output of the adder in the immediately preceding delay stage, the output of the adder in the last delay stage providing the output of the corresponding circuit path.
Claim 56
Dependent Claim
134 words
The receiver of claim 49, further comprising: a first squaring circuit and a multiply-by-N scalar circuit connected in series and interposed between the input of the second circuit path and the inputs of the FIFO register and adder of the first delay stage in the second circuit path; a second squaring circuit having an input coupled to the output of the first circuit path and an output; and a subtracter having a first input coupled to the output of the second circuit path, a second input coupled to the output of the second squaring circuit, and an output; wherein the output of the first circuit path provides the first digital output of the storage and calculation circuit and the output of the subtracter provides the second digital otuput of the storage and calculation circuit.
Claim 57
Dependent Claim
63 words
The receiver of claim 50, further comprising a latch circuit having a digital input coupled to the digital input of the storage and calculation circuit, a digital output coupled to the inputs of the first and second circuit paths, a set input coupled to the enable input of the storage and calculation circuit, and a reset input coupled to a clock signal source.
Claim 58
Dependent Claim
131 words
The receiver of claim 48, wherein said fourth means comprises: a first comparator having a first input coupled to the first digital output of the storage and calculation circuit, a second input, and an output; means for applying said predetermined minimum mean value to the second input of said first comparator; a second comparator having a first input coupled to the second digital output of the storage and calculation circuit, a second input, and an output; means for applying said predetermined maximum variance value to the second input of said second comparator; and an AND circuit having first and second inputs coupled to the outputs of the first and second comparators, respectively, and an output, the output of said AND circuit indicating the absence or presence of a burst signal transmission.
Claim 59
Dependent Claim
72 words
The receiver of claim 42, wherein said signal processing circuit comprises: a control and switching circuit having a signal input to which the received signal is applied, an enable input coupled to said fourth means, and a plurality of signal outputs; and a plurality of demodulation circuits, each coupled to a corresponding signal output of said control and switching circuit, for simultaneously demodulating the data contained in a plurality of received signals.
Claim 60
Dependent Claim
209 words
A communication system comprising: a transmitter for transmitting a burst signal transmission containing a sequence of N acquisition codes occurring at predetermined time intervals and followed by data; a receiver for receiving and detecting said burst signal transmission, said receiver comprising an acquisition circuit and a signal processing circuit, said acquisition circuit comprising: first means for generating a correlation output having a magnitude proportional to the similarity between successively received portions of the burst signal transmission and a stored acquisition code pattern; second means coupled to said first means for detecting and measuring peaks in the magnitude of said correlation output; third means coupled to said second means for forming a group of N peak magnitudes occurring at time intervals corresponding to said predetermined time intervals, and for computing values proportional to the mean value and variance, respectively, of said group of N peak magnitudes; and fourth means coupled to said third means for comparing the computed values proportional to the mean value and variance to predetermined minimum and maximum values, respectively, and for indicating the presence of a burst signal transmission when the computed value proportional to the mean value exceeds said minimum value and the computed value proportional to the variance is less than said maximum value.
Claim 61
Dependent Claim
209 words
A communication system comprising: a transmitter for transmitting a burst signal transmission containing a sequence of N acquisition codes occurring at predetermined time intervals and followed by data; a receiver for receiving and detecting said burst signal transmission, said receiver comprising an acquisition circuit and a signal processing circuit, said acquisition circuit comprising: first means for generating a correlation output having a magnitude proportional to the similarity between successively received portions of the burst signal transmission and a stored acquisition code pattern; second means coupled to said first means for detecting and measuring peaks in the magnitude of said correlation output; third means coupled to said second means for forming a group of N peak magnitudes occurring at time intervals corresponding to said predetermined time intervals, and for computing values proportional to the mean value and variance, respectively, of said group of N peak magnitudes; and fourth means coupled to said third means for comparing the computed values proportional to the mean value and variance to predetermined minimum and maximum values, respectively, and for indicating the presence of a burst signal transmission when the computed value proportional to the mean value exceeds said minimum value and the computed value proportional to the variance is less than said maximum value.
Claim 62
Dependent Claim
15 words
The communication system of claim 54, wherein said acquisition codes are identical to each other.
Claim 63
Dependent Claim
16 words
The communication system of claim 54, wherein said predetermined time intervals are equal to each other.
Claim 64
Dependent Claim
45 words
The communication system of claim 54, wherein said burst signal transmission comprises a digital bit stream modulated on a carrier frequency, and wherein said first means comprises means for repeatedly comparing the most recently received bits of the received signal with stored acquisition code bits.
Claim 65
Dependent Claim
55 words
The communication system of claim 54, wherein said first means comprises: a matched surface acoustic wave filter having an input to which the received signal is applied and an output; and an envelope detector having an input connected to the output of the surface acoustic wave filter and an output connected to said second means.
Claim 66
Dependent Claim
68 words
The communication system of claim 58, wherein said second means comprises: a peak detector having an input coupled to the output of said envelope detector and an output; and an analog-to-digital converter having an analog signal input coupled to the output of said envelope detector, an enable input coupled to the output of the peak detector, and a digital output coupled to the input of said third means.
Claim 67
Dependent Claim
63 words
The communication system of claim 59, wherein said third means comprises a storage and calculation circuit having a digital input coupled to the digital output of the analog-to-digital converter, an enable input coupled to the output of the peak detector, and first and second digital outputs for providing the computed values proportional to the mean value and variance, respectively, to said fourth means.
Claim 68
Dependent Claim
194 words
The communication system of claim 60, wherein said storage and calculation circuit comprises first and second circuit paths, each of said circuit paths having an input coupled to the digital input of the storage and calculation circuit, an output, and a series of N-1 delay stages between said input and said output, each delay stage comprising: a clocked first-in-first-out (FIFO) register having an input and an output, said FIFO register having a length sufficient to provide a delay equal to the predetermined interval between successive acquisition codes; and an adder having a first input coupled to the output of the FIFO register, a second input coupled to the digital input of the storage and calculation circuit, and an output; said delay stages being connected in a manner such that the FIFO register of the first delay stage has its input coupled to the digital input of the storage and calculation circuit, and the FIFO register of each succeeding delay stage has its input coupled to the output of the adder in the immediately preceding delay stage, the output of the adder in the last delay stage providing the output of the corresponding circuit path.
Claim 69
Dependent Claim
135 words
The communication system of claim 61, further comprising: a first squaring circuit and a multiply-by-N scalar circuit connected in series and interposed between the input of the second circuit path and the inputs of the FIFO register and adder of the first delay stage in the second circuit path; a second squaring circuit having an input coupled to the output of the first circuit path and an output; and a subtracter having a first input coupled to the output of the second circuit path, a second input coupled to the output of the second squaring circuit, and an output; wherein the output of the first circuit path provides the first digital output of the storage and calculation circuit and the output of the subtracter provides the second digital otuput of the storage and calculation circuit.
Claim 70
Dependent Claim
64 words
The communication system of claim 62, further comprising a latch circuit having a digital input coupled to the digital input of the storage and calculation circuit, a digital output coupled to the inputs of the first and second circuit paths, a set input coupled to the enable input of the storage and calculation circuit, and a reset input coupled to a clock signal source.
Claim 71
Dependent Claim
132 words
The communication system of claim 60, wherein said fourth means comprises: a first comparator having a first input coupled to the first digital output of the storage and calculation circuit, a second input, and an output; means for applying said predetermined minimum mean value to the second input of said first comparator; a second comparator having a first input coupled to the second digital output of the storage and calculation circuit, a second input, and an output; means for applying said predetermined maximum variance value to the second input of said second comparator; and an AND circuit having first and second inputs coupled to the outputs of the first and second comparators, respectively, and an output, the output of said AND circuit indicating the absence or presence of a burst signal transmission.
Claim 72
Dependent Claim
73 words
The communication system of claim 54, wherein said signal processing circuit comprises: a control and switching circuit having a signal input to which the received signal is applied, an enable input coupled to said fourth means, and a plurality of signal outputs; and a plurality of demodulation circuits, each coupled to a corresponding signal output of said control and switching circuit, for simultaneously demodulating the data contained in a plurality of received signals.
Claim 73
Dependent Claim
14 words
The communication system of claim 54, wherein said transmitter comprises a remote mobile transmitter.
Claim 74
Dependent Claim
14 words
The communication system of claim 54, wherein a plurality of said transmitters are provided.
Claim 75
Dependent Claim
25 words
The communication system of claim 54, wherein said burst signal transmission is relayed from the transmitter to the receiver through at least one relay satellite.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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