Spread spectrum communication device
First Claim
1. A spread spectrum communication method for communicating data by spreading the spectrum thereof, comprising:
- A) on the transmitter side;
a) a step of generating a spread-spectrum-modulated output including a first modulated output portion which is spread-spectrum-modulated and contains no data to be transmitted and a second modulated output portion which is spread-spectrum-modulated, follows said first modulated output portion, and contains data to be transmitted; and
b) a step of transmitting said spread-spectrum-modulated output so as to transmit said second modulated output portion with a low electric power and said first modulated output portion with a high electric power; and
B) on the receiver side;
a) a step of correlation-demodulating a received input to generate a correlation-demodulated output which includes a first correlation-demodulated output portion corresponding to said first modulated output portion and a second correlation-demodulated output portion corresponding to said second modulated output portion;
b) a step of detecting from said correlation-demodulated output said first correlation-demodulated output portion, wherein only a portion of said correlation-demodulated output exceeding a predetermined threshold is detected as said first correlation-demodulated output portion; and
c) a step of generating a timing signal serving as a reference for an operation on the receiver side, starting from said first correlation-demodulated output portion.
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Accused Products
Abstract
In a spread spectrum communication system for communicating data by spreading spectrum thereof, using PN codes, on the transmitter side, a first modulated output portion, which is spread-spectrum-modulated, containing no data to be transmitted and a second modulated output portion, which is spread-spectrum-modulated, following the first modulated output portion and containing data to be transmitted are generated; and the second modulated output portion is transmitted with a low electric power and the first modulated output portion with a high electric power. On the receiver side, a correlation-demodulated output is generated by correlation-demodulating a received input; and from the correlation-demodulated output consisting of a first correlation-demodulated output portion corresponding to the first modulated output portion and a second correlation-demodulated output portion corresponding to the second modulated output portion the first correlation-demodulated output portion is detected. Further timing signal serving as a reference for an operation on the receiver side is generated, starting from the first correlation-demodulated output portion.
44 Citations
12 Claims
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1. A spread spectrum communication method for communicating data by spreading the spectrum thereof, comprising:
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A) on the transmitter side; a) a step of generating a spread-spectrum-modulated output including a first modulated output portion which is spread-spectrum-modulated and contains no data to be transmitted and a second modulated output portion which is spread-spectrum-modulated, follows said first modulated output portion, and contains data to be transmitted; and b) a step of transmitting said spread-spectrum-modulated output so as to transmit said second modulated output portion with a low electric power and said first modulated output portion with a high electric power; and B) on the receiver side; a) a step of correlation-demodulating a received input to generate a correlation-demodulated output which includes a first correlation-demodulated output portion corresponding to said first modulated output portion and a second correlation-demodulated output portion corresponding to said second modulated output portion; b) a step of detecting from said correlation-demodulated output said first correlation-demodulated output portion, wherein only a portion of said correlation-demodulated output exceeding a predetermined threshold is detected as said first correlation-demodulated output portion; and c) a step of generating a timing signal serving as a reference for an operation on the receiver side, starting from said first correlation-demodulated output portion. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A spread spectrum communication device for communicating data by spreading the spectrum thereof, comprising:
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A) a transmitter which includes; a) period specifying means for determining a packet period which includes a burst period containing no data to be transmitted and a data period following said burst period and containing data to be transmitted; b) PN code train generating means for generating a PN code train which includes a repetition of first PN codes with a predetermined period; c) modulating signal generating means for generating a modulating signal which includes said data to be transmitted during said data period and includes no data during said burst period; d) spread-spectrum-modulating means for generating a spread-spectrum-modulated output by spread-spectrum-modulating said PN code train with said modulating signal; e) transmission power specifying means for generating a transmission power specifying signal which specifies a high transmission power during said burst period and a low transmission power during said data period; and f) transmission power control means for transmitting said spread-spectrum-modulated output with an electric power corresponding to said transmission power specifying signal; and B) a receiver which includes; a) means for obtaining a frequency-converted output by frequency-converting a received input; b) correlator means for generating a correlation output from said frequency-converted output by using a PN code train which includes a repetition of second PN codes inverted in time with respect to said first PN code; c) burst detecting means for comparing said correlation output with a predetermined threshold and for generating a timing signal when said correlation output is greater than said predetermined threshold, said predetermined threshold being lower than a level of said correlation output during said burst period but higher than the level of said correlation output during said data period; and d) data demodulating means for demodulating said correlation output by using said timing signal as a time reference. - View Dependent Claims (8, 10, 11, 12)
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9. A spread spectrum communication device for communicating data by spreading the spectrum thereof, comprising:
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A) a transmitter which includes; a) period specifying means for determining a packet period which includes a burst period containing no data to be transmitted and a data period following said burst period and containing data to be transmitted; b) PN code train generating means for generating a PN code train which includes a repetition of first PN codes with a predetermined period; c) modulating signal generating means for generating a modulating signal which includes said data to be transmitted during said data period and includes no data during said burst period; d) spread-spectrum-modulating means for generating a spread-spectrum-modulated output by spread-spectrum-modulating said PN code train with said modulating signal; e) transmission power specifying means for generating a transmission power specifying signal which specifies a high transmission power during said burst period and a low transmission power during said data period; and f) transmission power control means for transmitting said spread-spectrum-modulated output with an electric power corresponding to said transmission power specifying signal; and B) a receiver which includes; a) means for obtaining a frequency-converted output by frequency-converting a received input; b) correlator means for generating a correlation output from said frequency-converted output by using a PN code train which includes a repetition of second PN codes inverted in time with respect to said first PN code; c) burst detecting means for comparing said correlation output with a predetermined threshold and for generating a timing signal when said correlation output is greater than said predetermined threshold, said predetermined threshold being lower than a level of said correlation output during said burst period but higher than the level of said correlation output during said data period; and d) data demodulating means for demodulating said correlation output by using said timing signal as a time reference wherein said transmission power control means includes; a) a first transformer receiving said spread-spectrum-modulated output by a primary winding thereof and said transmission power specifying signal by a center tap of a secondary winding thereof; and b) a second transformer including a primary winding with two extremities which are connected with two extremities of said second winding of said first transformer through two diodes, respectively, and whose center tap is grounded, and a secondary winding for generating an output.
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Specification