IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
UP-0429392
(2006-05-04)
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등록번호 |
US-7660341
(2010-04-02)
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우선권정보 |
FR-05 04588(2005-05-04); FR-05 04589(2005-05-04); FR-05 04591(2005-05-04) |
발명자
/ 주소 |
- Durand, Benoit
- Fraschini, Christophe
- Courmontagne, Philippe
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출원인 / 주소 |
- STMicroelectronics (Rousset) SAS
- Universite de Provence (AIX Marsielle)
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
2 인용 특허 :
12 |
초록
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A receiver device for a modulated signal, suited in particular to a transmission system using a binary carrier phase modulation by means of a binary message on which a direct sequence spread spectrum operation has been carried out, this device comprising a first analog radio frequency part, transfor
A receiver device for a modulated signal, suited in particular to a transmission system using a binary carrier phase modulation by means of a binary message on which a direct sequence spread spectrum operation has been carried out, this device comprising a first analog radio frequency part, transforming the signal received into a low-frequency, demodulated signal, said demodulated signal being applied to a second digital part of said device comprising an analog-to-digital converter and a filter matched to the spreading code used in order to delete the spreading applied to the original message, said device being characterized in that it includes an additional filtering unit, arranged between the analog-to-digital converter and the matched filter, said filtering unit implementing a stochastic matched filtering operation in order to improve the signal-to-noise ratio at the input of said matched filter.
대표청구항
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The invention claimed is: 1. Receiver device for a modulated signal, suited in particular to a transmission system using a binary carrier phase modulation by means of a binary message on which a direct sequence spread spectrum operation has been carried out, this device comprising a first analog ra
The invention claimed is: 1. Receiver device for a modulated signal, suited in particular to a transmission system using a binary carrier phase modulation by means of a binary message on which a direct sequence spread spectrum operation has been carried out, this device comprising a first analog radio frequency part, transforming the signal received into a low-frequency, demodulated signal, said demodulated signal being applied to a second digital part of said device comprising an analog-to-digital converter and a filter matched to the spreading code used in order to delete the spreading applied to the original message, said device being characterized in that it includes an additional filtering unit, arranged between the analog-to-digital converter and the matched filter, said filtering unit implementing a stochastic matched filtering operation in order to improve the signal-to-noise ratio at the input of said matched filter. 2. Receiver device as claimed in claim 1, wherein the additional filtering unit includes a plurality Q of digital, finite impulse response base filters mounted in parallel, each of which receives an undersampled sampled signal supplied at the output of the analog-to-digital converter, each filter being characterized by a set of K coefficients, this number K being determined such that it corresponds to the minimum number of samples for describing one bit of the spread message, the coefficients of each of the Q filters corresponding respectively to components of Q eigen vectors associated with at least Q eigenvalues greater than 1 of the matrix B−1A, where B is a variance-covariance matrix of the resultant noise after demodulation and A is a variance-covariance matrix of the wanted signal. 3. Receiver device as claimed in claim 2, wherein for each filter of the plurality Q of finite impulse response filters, the additional filtering unit includes means for multiplying the signal obtained at the output of said filter, with, respectively, the vector resulting from the product between the variance-covariance matrix of the noise B and the eigen vector defining the coefficients of said filter, said unit further comprising means of summing up the vectors resulting from all of these operations, supplying a signal corresponding to the output signal of the reformatted analog-to-digital converter having an improved signal-to-noise ratio. 4. Receiver device as claimed in claim 1, further comprising first and second hysteresis comparators installed at the output of the filter matched to the spreading code, capable of comparing the amplitude of the output signal of the matched filter to a lower threshold value and upper threshold value, and of delivering, respectively, the original binary message and its associated synchronization clock for capturing the data of said message. 5. Receiver device as claimed in claim 4, wherein the first and second comparators have adjustable upper and lower threshold values. 6. Receiver device as claimed in claim 1, wherein the filter matched to the spreading code used is a finite impulse response filter. 7. Receiver device as claimed in claim 1, wherein the noise corresponds to the transmission channel noise. 8. A receiver, comprising: a demodulator operable to recover from a modulated analog signal a demodulated analog signal including a first component having a frequency spectrum spread according to a spreading code and including a second component; an analog-to-digital converter coupled to the demodulator and operable to convert the demodulated analog signal into a demodulated digital signal including the digitized first and second components having respective strengths; an emphasizer coupled to the converter and operable to generate a modified demodulated digital signal from the demodulated digital signal by increasing the strength of the digitized first component of the demodulated digital signal relative to the strength of the digitized second component; and a de-spreader coupled to the emphasizer and operable to generate a digital baseband signal from the modified demodulated digital signal and the spreading code. 9. The receiver of claim 8 wherein the second component of the modulated analog signal comprises a noise component. 10. The receiver of claim 8, further comprising: an amplifier coupled to the demodulator and operable to receive and amplify the modulated analog signal; and wherein the demodulator is operable to recover the demodulated analog signal from the amplified modulated analog signal. 11. The receiver of claim 8 where the demodulator comprises: an oscillator operable to generate a demodulation signal having a frequency substantially equal to a carrier frequency associated with the modulated analog signal; and a mixer coupled to the oscillator, operable to receive the modulated analog signal, and operable to generate the demodulated analog signal as a product of the modulated analog signal and the demodulation signal. 12. The receiver of claim 8, further comprising: wherein the first component of the demodulated analog signal has a bandwidth; and a low-pass filter coupled between the demodulator and the analog-to-digital converter and operable to limit the bandwidth of the demodulated analog signal to substantially the bandwidth of the first component. 13. The receiver of claim 8, further comprising: wherein the baseband digital signal comprises an amplitude; and a comparator coupled to the de-spreader and operable to generate a binary signal having a first level if the amplitude of the baseband digital signal is greater than a first threshold and having a second level if the amplitude of the baseband digital signal is less than a second threshold. 14. The receiver of claim 8 wherein the emphasizer comprises: a finite-impulse-response filter operable to generate an intermediate signal from the demodulated digital signal; and a multiplier coupled to the filter and operable to generate the modified demodulated digital signal from a product of the intermediate signal and a predetermined value. 15. The receiver of claim 8 wherein the emphasizer comprises: finite-impulse-response filters each operable to generate a respective first intermediate signal from the demodulated digital signal; multipliers each coupled to a respective filter and each operable to generate a respective second intermediate signal equal to a product of a respective first intermediate signal and a respective predetermined value; and an adder circuit operable to generate the modified demodulated digital signal from a sum of the second intermediate signals. 16. The receiver of claim 8 wherein: the first component of the demodulated digital signal has a symbol rate; the analog-to-digital converter operates at a sampling rate; and the emphasizer comprises, a finite-impulse-response filter having an order related to a quotient of the sampling rate divided by the symbol rate and operable to generate an intermediate signal from the demodulated digital signal, and a multiplier coupled to the filter and operable to generate the modified demodulated digital signal from a product of the intermediate signal and a predetermined value. 17. The receiver of claim 8 wherein the emphasizer comprises: a finite-impulse-response filter having one or more coefficients related to an autocorrelation of the spreading code and operable to generate an intermediate signal from the demodulated digital signal; and a multiplier coupled to the filter and operable to generate the modified demodulated digital signal from a product of the intermediate signal and a predetermined value. 18. The receiver of claim 8 wherein the emphasizer comprises: a finite-impulse-response filter having one or more coefficients related to an autocorrelation of the second component of the demodulated analog signal and operable to generate an intermediate signal from the demodulated digital signal; and a multiplier coupled to the filter and operable to generate the modified demodulated digital signal from a product of the intermediate signal and a predetermined value. 19. The receiver of claim 8 wherein the emphasizer comprises: a finite-impulse-response filter having coefficients related to elements of an eigen vector of a product of a variance-covariance matrix of the spreading code and a transpose of a variance-covariance matrix of the second component of the demodulated analog signal, the eigen vector being associated with an eigen value of the product greater than one, the filter operable to generate an intermediate signal from the demodulated digital signal; and a multiplier coupled to the filter and operable to generate the modified demodulated digital signal from a product of the intermediate signal and a vector value related to a product of the variance-covariance matrix of the second component of the demodulated analog signal and the eigen vector. 20. The receiver of claim 8 wherein the emphasizer comprises: a finite-impulse-response filter having coefficients respectively equal to elements of an eigen vector of a product of a variance-covariance matrix of the spreading code and a transpose of a variance-covariance matrix of the second component of the demodulated analog signal, the eigen vector being associated with an eigen value of the product greater than one, the filter operable to generate an intermediate signal from the demodulated digital signal; and a multiplier coupled to the filter and operable to generate the modified demodulated digital signal as a vector equal to a product of the intermediate signal and a vector value equal to a product of the variance-covariance matrix of the second component of the demodulated analog signal and the eigen vector. 21. A system, comprising: a receiver, comprising, a demodulator operable to recover from a modulated analog signal a demodulated analog signal including a first component having a frequency spectrum spread according to a spreading code and including a second component, an analog-to-digital converter coupled to the demodulator and operable to convert the demodulated analog signal into a demodulated digital signal including the digitized first and second components having respective strengths, an emphasizer coupled to the converter and operable to generate a modified demodulated digital signal from the demodulated digital signal by increasing the strength of the digitized first component of the demodulated digital signal relative to the strength of the digitized second component, and a de-spreader coupled to the emphasizer and operable to generate a digital baseband signal from the modified demodulated digital signal and the spreading code. 22. A method, comprising: receiving a modulated analog signal at a receiver; demodulating the modulated analog signal, the demodulated analog signal including a first component having a frequency spectrum spread according to a spreading code and including a second component; converting the demodulated analog signal into a demodulated digital signal including the digitized first and second components having respective power levels; modifying the demodulated digital signal by lowering the power level of the digitized second component relative to the power level of the digitized first component; de-spreading the modified demodulated digital signal using the spreading code; and outputting the digital baseband signal at an output of the receiver. 23. The method of claim 22, further comprising: receiving the analog signal from a propagation channel; and wherein the second component of the demodulated analog signal comprises noise from the channel. 24. The method of claim 22, further comprising limiting the bandwidth of the demodulated analog signal to substantially the bandwidth of the first component before converting the demodulated analog signal. 25. The method of claim 22, further comprising generating a binary signal having a first level if the amplitude of the de-spread signal is greater than a first threshold and having a second level if the amplitude of the de-spread signal is less than a second threshold. 26. The method of claim 22 wherein the first threshold equals the second threshold. 27. The method of claim 22 wherein modifying the demodulated signal comprises: generating an intermediate signal from the demodulated digital signal using a finite-impulse-response filter; and generating the modified demodulated digital signal by multiplying the intermediate signal by a predetermined value. 28. The method of claim 22 wherein modifying the demodulated signal comprises: generating first intermediate signals from the demodulated signal using respective finite-impulse-response filters; generating second intermediate signals by multiplying each of the first intermediate signals by a respective predetermined value; and generating the modified demodulated digital signal by summing together the second intermediate signals. 29. The method of claim 22 wherein: converting the demodulated analog signal comprises converting the demodulated analog signal at a sampling rate; the first component of the demodulated digital signal has a symbol rate; and modulating the demodulated digital signal comprises, generating an intermediate signal from the demodulated digital signal with a finite-impulse-response filter having an order related to a quotient of the sampling rate divided by the symbol rate, and generating the modified demodulated digital signal by multiplying the intermediate signal by a predetermined value. 30. The method of claim 22 wherein modifying the demodulated signal comprises: generating an intermediate signal from the demodulated digital signal using a finite-impulse-response filter having one or more coefficients related to an autocorrelation of the spreading code; and generating the modified demodulated digital signal by multiplying the intermediate signal by a predetermined value. 31. The method of claim 22 wherein modifying the demodulated signal comprises: generating an intermediate signal from the demodulated digital signal using a finite-impulse-response filter having one or more coefficients related to an autocorrelation of the second component of the demodulated analog signal; and generating the modified demodulated digital signal by multiplying the intermediate signal by a predetermined value. 32. The method of claim 22 wherein modifying the demodulated signal comprises: generating an intermediate signal from the demodulated digital signal using a finite-impulse-response filter having one or more coefficients related to an autocorrelation of the second component of the demodulated digital signal; and generating the modified demodulated digital signal by multiplying the intermediate signal by a predetermined value. 33. The method of claim 22 wherein modifying the demodulated signal comprises: generating an intermediate signal from the demodulated digital signal using a finite-impulse-response filter having coefficients related to elements of an eigen vector of a product of a variance-covariance matrix of the spreading code and a transpose of a variance-covariance matrix of the second component of the demodulated analog signal, the eigen vector being associated with an eigen value of the product greater than one; and generating the modified demodulated digital signal by multiplying the intermediate signal by a vector value related to a product of the variance-covariance matrix of the second component of the demodulated analog signal and the eigen vector. 34. The method of claim 22 wherein modifying the demodulated signal comprises: generating an intermediate signal from the demodulated digital signal using a finite-impulse-response filter having coefficients related to elements of an eigen vector of a product of a variance-covariance matrix of the spreading code and a transpose of a variance-covariance matrix of the second component of the modulated analog signal, the eigen vector being associated with an eigen value of the product greater than one; and generating the modified demodulated digital signal by multiplying the intermediate signal by a vector value related to a product of the variance-covariance matrix of the second component of the modulated analog signal and the eigen vector. 35. The method of claim 22 wherein modifying the demodulated signal comprises: generating an intermediate signal from the demodulated digital signal using a finite-impulse-response filter having coefficients related to elements of an eigen vector of a product of a variance-covariance matrix of the spreading code and a transpose of a variance-covariance matrix of the second component of the demodulated digital signal, the eigen vector being associated with an eigen value of the product greater than one; and generating the modified demodulated digital signal by multiplying the intermediate signal by a vector value related to a product of the variance-covariance matrix of the second component of the demodulated digital signal and the eigen vector. 36. The method of claim 22 wherein modifying the demodulated signal comprises: generating an intermediate signal from the demodulated digital signal using a finite-impulse-response filter having coefficients respectively equal to elements of an eigen vector of a product of a variance-covariance matrix of the spreading code and a transpose of a variance-covariance matrix of the second component of the demodulated analog signal, the eigen vector being associated with an eigen value of the product greater than one; and generating the modified demodulated digital signal as a vector by multiplying the intermediate signal by a vector value equal to a product of the variance-covariance matrix of the second component of the demodulated analog signal and the eigen vector.
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