IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
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출원번호 |
US-0686270
(2007-03-14)
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등록번호 |
US-8300721
(2012-10-30)
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발명자
/ 주소 |
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출원인 / 주소 |
- Agilent Technologies, Inc.
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인용정보 |
피인용 횟수 :
0 인용 특허 :
2 |
초록
▼
A method for receiving spread spectrum signals and for initial code acquisition from the received signals comprises de-spreading the received signals, based on code phase synchronization, to produce a de-spread signal; and performing a modulation detection based on a change of time-domain characteri
A method for receiving spread spectrum signals and for initial code acquisition from the received signals comprises de-spreading the received signals, based on code phase synchronization, to produce a de-spread signal; and performing a modulation detection based on a change of time-domain characteristic of the de-spread signal.
대표청구항
▼
1. An initial code acquisition method, comprising: receiving a spread spectrum signal including symbols;de-spreading the received spread spectrum signal based on code phase synchronization to produce a de-spread signal; anddetecting a modulation format of the received spread spectrum signal based on
1. An initial code acquisition method, comprising: receiving a spread spectrum signal including symbols;de-spreading the received spread spectrum signal based on code phase synchronization to produce a de-spread signal; anddetecting a modulation format of the received spread spectrum signal based on a change of a time-domain characteristic of the de-spread signal,wherein the change of a time-domain characteristic comprises a magnitude variation in a despread symbol in the de-spread signal. 2. A method as recited in claim 1, wherein the de-spreading is based on frequency offset and code phase synchronization. 3. A method as recited in claim 2, wherein: a range of code phase to be searched is determined by a propagation delay of the spread spectrum signal; anda range of frequency offset to be searched is determined by a Doppler frequency shift of the spread spectrum signal. 4. A method as recited in claim 1, where the de-spreading includes de-scrambling. 5. A method as recited in claim 4, wherein the de-scrambling employs a scrambling sequence that is a function of a code phase. 6. A method as recited in claim 1, wherein the de-spreading includes de-spreading at one of a set of code channels, each of the code channels being based on a respective one of a set of orthogonal functions. 7. A method as recited in claim 6, wherein: the set of orthogonal functions includes a set of Walsh functions, each of the orthogonal functions comprising a respective one of the Walsh functions; andthe de-spreading includes de-scrambling and de-spreading at a predetermined Walsh code channel that corresponds with the respective one of the Walsh functions. 8. A method as recited in claim 7, wherein the de-spreading includes: generating a scrambling sequence based on a code phase and a frequency offset;multiplying the received signal by the scrambling sequence to produce a product thereof; andmultiplying the product by the respective one of the Walsh functions. 9. A method as set forth in claim 1, wherein detecting the modulation format of the received spread spectrum signal includes recognizing a modulation format from among a plurality of possible modulation formats for the spread spectrum signal; anddetecting a threshold activity at the recognized modulation format. 10. A method as recited in claim 9, wherein recognizing the modulation format includes recognizing based on Walsh code channels. 11. A method as recited in claim 1, wherein: the received spread spectrum signal is modulated with one of a plurality of possible modulation formats; anddetecting the modulation format of the received spread spectrum signal includes:(i) calculating a metric for each of the possible modulation formats,(ii) comparing the calculated metric for the modulation format to a threshold, and(iii) detecting the presence of a given one of the modulation formats based on the comparison with the threshold. 12. A method as recited in claim 11, wherein the calculating a metric includes calculating the magnitude variation in the de-spread signal. 13. An initial code acquisition system, comprising: de-spreading circuitry for de-spreading a received spread spectrum signal based on code phase synchronization to produce a de-spread signal comprising symbols; anda modulation detector for detecting a modulation format of the received spread spectrum signal based on a change of a time-domain characteristic of the de-spread signal,wherein the change of a. time-domain characteristic comprises a magnitude variation in a despread symbol in the de-spread signal. 14. A system as recited in claim 13, wherein the de-spreading circuitry includes circuitry that is operable based on frequency offset and code phase synchronization. 15. A system as recited in claim 14, wherein: a range of code phase to be searched is determined by a propagation delay of the spread spectrum signal; anda range of frequency offset to be searched is determined by a Doppler frequency shift of the spread spectrum signal. 16. A system as recited in claim 13, where the de-spreading circuitry includes de-scrambling circuitry, 17. A system as recited in claim 16, wherein the de-scrambling circuitry employs a scrambling sequence that is a function of a code phase. 18. A system as recited in claim 13, wherein the de-spreading circuitry includes de-spreading circuitry for de-spreading at one of a set of code channels, each of the code channels being based on a respective one of a set of orthogonal functions. 19. A system as recited in claim 18, wherein: the set of orthogonal functions includes a set of Walsh functions, each of the orthogonal functions comprising a respective one of the Walsh functions; andthe de-spreading circuitry includes circuitry for de-scrambling and de-spreading at a predetermined Walsh code channel that corresponds with the respective one of the Walsh functions. 20. A system as recited in claim 19, wherein the de-spreading circuitry includes: scrambling sequence generating circuitry that is operable based on a code phase and a frequency offset;first multiplying circuitry for multiplying the received signal by the scrambling sequence to produce a product thereof; andsecond multiplying circuitry for multiplying the product by the respective one of the Walsh functions. 21. A system as set forth in claim 13, wherein the modulation detector includes: circuitry for recognizing a modulation format from among a plurality of possible modulation formats for the spread spectrum signal; andcircuitry for detecting a threshold activity at the recognized modulation format. 22. A system as recited in claim 21, wherein the circuitry for recognizing includes circuitry for recognizing based on Walsh code channels. 23. A system as recited in claim 21, wherein: the received spread spectrum signal is modulated with one of a plurality of possible modulation formats; andthe modulation detection circuitry includes:(i) circuitry for calculating a metric for each of the possible modulation formats,(ii) circuitry for comparing the calculated metrics to a threshold, and(iii) circuitry for detecting the presence of a given one of the modulation formats based on the comparison with the threshold. 24. A system as recited in claim 23, wherein the circuitry for calculating a metric includes circuitry for calculating the magnitude variation in the de-spread signal. 25. A system as recited in any of claims 13-24, wherein circuitry recited therein is implemented as a processor and software for performing the operation of the recited circuitry. 26. A non-transitory computer-readable medium encoded with a computer program, for directing a processing system to perform initial code acquisition for received spread spectrum signals, the computer-readable medium comprising: software program code, provided on the computer-readable medium, for directing the processing system to perform a method as recited in any of claims 1-12.
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