WO2005040848A1 - Enlevement par cross-correlation de signaux de brouillage intentionnel d'ondes porteuses - Google Patents

Enlevement par cross-correlation de signaux de brouillage intentionnel d'ondes porteuses Download PDF

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Publication number
WO2005040848A1
WO2005040848A1 PCT/US2004/035350 US2004035350W WO2005040848A1 WO 2005040848 A1 WO2005040848 A1 WO 2005040848A1 US 2004035350 W US2004035350 W US 2004035350W WO 2005040848 A1 WO2005040848 A1 WO 2005040848A1
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WO
WIPO (PCT)
Prior art keywords
signal
carrier wave
wave jamming
spread spectrum
phase
Prior art date
Application number
PCT/US2004/035350
Other languages
English (en)
Inventor
Paul A. Underbrink
Henry D. Falk
Charles P. Norman
Original Assignee
Sirf Technology, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US10/689,565 external-priority patent/US7822105B2/en
Priority claimed from PCT/US2004/028542 external-priority patent/WO2005022187A2/fr
Application filed by Sirf Technology, Inc. filed Critical Sirf Technology, Inc.
Publication of WO2005040848A1 publication Critical patent/WO2005040848A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/21—Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
    • G01S19/215—Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service issues related to spoofing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/246—Acquisition or tracking or demodulation of signals transmitted by the system involving long acquisition integration times, extended snapshots of signals or methods specifically directed towards weak signal acquisition
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/35—Constructional details or hardware or software details of the signal processing chain
    • G01S19/37—Hardware or software details of the signal processing chain
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0205—Details
    • G01S5/0221—Receivers
    • G01S5/02213—Receivers arranged in a network for determining the position of a transmitter
    • G01S5/02216—Timing or synchronisation of the receivers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/707—Spread spectrum techniques using direct sequence modulation
    • H04B1/7097—Interference-related aspects
    • H04B1/71—Interference-related aspects the interference being narrowband interference
    • H04B1/7101—Interference-related aspects the interference being narrowband interference with estimation filters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K3/00—Jamming of communication; Counter-measures
    • H04K3/20—Countermeasures against jamming
    • H04K3/22—Countermeasures against jamming including jamming detection and monitoring
    • H04K3/224—Countermeasures against jamming including jamming detection and monitoring with countermeasures at transmission and/or reception of the jammed signal, e.g. stopping operation of transmitter or receiver, nulling or enhancing transmitted power in direction of or at frequency of jammer
    • H04K3/228—Elimination in the received signal of jamming or of data corrupted by jamming
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/30—Acquisition or tracking or demodulation of signals transmitted by the system code related

Definitions

  • This invention relates generally to signal processing in a radio receiver and more particularly to removal of undesired signals received at the radio receiver.
  • RF carrier wave
  • CW jamming is a source of interference in spread spectrum systems, such as CDMA cellular telephone systems and satellite positioning systems.
  • Spread spectrum communication systems use lower power signals spread across the frequency spectrum and are subject to interference from carrier waves used in other communication systems.
  • the problem of CW jamming is further complicated because of the geographical area covered by spread spectrum system may include the whole Earth, for example the United States' Global Position System
  • Systems consistent with the present invention provide a receiver that is capable of receiving a spread spectrum signal that contains a CW jamming signal along with a weak signal.
  • the signal is processed with a crosscorrelator that enables the CW jamming signal to be identified, tracked, and reproduced.
  • the replicated CW jamming signal is subtracted from the received signal after demodulation, thus enabling the weak signal to be processed.
  • FIG. 1 is a flow diagram depicting strong signal cancellation in a weak spread spectrum signal using crosscorrelation.
  • FIG. 2 illustrates a signal-processing diagram for identifying and removing CW jamming signals where the cancelled signal of FIG. 1 maybe the CW jamming signal.
  • FIG. 3 is a block diagram of electrical components of FIG. 2.
  • FIG. 4 is a flow diagram of the identifying and removing CW jamming signals.
  • FIG. 1 a flow diagram 100 depicting strong signal cancellation in a weak spread spectrum signal using crosscorrelation is shown.
  • a strong/weak or near/far signal isolation provided by a spread spectrum, pseudo random number (PRN) code family such as used in CDMA spread spectrum systems is dependent upon the crosscorrelation between the various code members of the family.
  • PRN pseudo random number
  • the isolation of two signals at the same frequency (or multiples of the code repetition rate, in this case 1 KHz) is about 21 to 23 dB. If the relative strengths of two signals differ by more than this limit, the weaker signal cannot be discriminated using only the spreading code.
  • a method of removing the effects of the stronger signal may be applied if the weaker signal is to be tracked.
  • the crosscorrelation effect is at its maximum when the relative Doppler frequency offset between the relatively strong and weak signals is an integer multiple of 1 KHz in the case of coarse acquisition code (C/A) in the GPS signals.
  • C/A coarse acquisition code
  • a general solution to the problem of tracking a weak signal spread spectrum signal in the presence of a stronger spread spectrum signal is based on the premise that all aspects of the strong signal's interference can either be measured or calculated in order to remove it from the weaker signal.
  • the solution can be implemented in any multi-channel receiver having the ability to control a channel's frequency and phase as well as selecting the desired spreading code and setting that code's phase position.
  • the receiver typically employs two channels, one to track the weak signal and one to track the interfering strong signal.
  • the channel that is used to track the strong signal is not required if the characteristics such as power, code phase and frequency of the strong signal can be obtained or accurately estimated by alternate means.
  • the procedure starts 102 with the strong signal being acquired 104, such as by tracking the strong signal in a first channel of the receiver.
  • the channel provides a measurement of the signal strength of the strong signal along with the phase of the ( carrier signal and the spreading code. Additional channels may be used to track additional strong signals (not shown in FIG. 1).
  • the code phase of the spreading code of the weaker signal are predicted 106 based on the 50Hz navigation data code data (D) by methods known in the art.
  • a second channel in the receiver is dedicated to receiving the compound carrier signal and tracking 108 the predicted weak signal component.
  • the second receiver channel correlates the incoming signal with the second code at the predicted frequency and signal phase.
  • the resulting in-phase and quadrature (I,Q) measurements contain both the weak signal and the strong signal, each spread by their unique code.
  • the product Code2R*Code2 is the autocorrelation of the received code 2 and the replica code 2.
  • the autocorrelation function has a value of 1 if the replica code is aligned with the received code. This crosscorrelation of replica code 2 with
  • Strong X (Code2R*CodeX) is next computed 110 to be removed from the compound signal.
  • Codel and Code2 are both members of a PRN code family, and their autocorrelation and crosscorrelation properties are known. It is therefore possible to calculate the crosscorrelation of the two codes at their respective phases by simply multiplying each bit of Codel by the corresponding (in time) bit of Code2 to produce their crosscorrelation value. Since there may be a relative Doppler frequency offset between the two codes, the phase of the codes will process past one another over time and create a new crosscorrelation function. For the GPS system the greatest delta code Doppler typically encountered is about plus or minus 9KHz which is equivalent to six code chips per second (1540 carrier cycles per code chip), and thus the maximum recalculation rate of the crosscorrelation value is roughly 6 times per second.
  • the maximum crosscorrelation occurs at a frequency offset of zero with peaks occurring at intervals of 1000Hz. There is an attenuation of the crosscorrelation as the frequency offset moves away from zero. This attenuation follows the well known sin(x)/x curve. If 10ms measurements are used for tracking or acquisition, the attenuation factor would be equal to sin( ⁇ freq* ⁇ /100 Hz)/( ⁇ freq* ⁇ /100 Hz). This produces an attenuation of -lOdB at about a 75Hz delta frequency. Other local peaks in the sin(x)/x curve (i.e. locally minimum attenuation) occur at 150Hz and 250Hz with attenuations of -13.5dB and -18dB, respectively. This implies that for a desired strong signal suppression of lOdB, only the first lobe of the sin(x)/x function need be considered; however, should additional suppression be desired, the entire curve may be considered.
  • the next step entails computing 112, for each strong signal, the product of the strong signal amplitude and the calculated frequency and time domain (code phase) crosscorrelation.
  • the weak signal is finally extracted by subtracting 114 this product from the compound signal and processing is complete 116.
  • the weak signal thus extracted is subsequently processed in the receiver circuitry as known in the art.
  • the in-phase (I) and quadrature amplitude (Q) of each strong signal is obtained by measurement in each strong signal's own individual receiver channel or by estimation through independent means. Because the strong signal is being actively tracked by the receiver's phase lock loops, the phase of the strong signal is presumed to be near zero radians and thus nearly all the signal power is in the in-phase portion.
  • a signal comprising a strong signal SI modulated with a first code Codel summed with a weak signal w2 modulated with a second code Code2 produces (Sl*codel+w2*Code2).
  • the sum of the two signals is correlated with a replica of the second code Code2R to produce ⁇ Code2R*(Sl*Codel+w2*Code2) ⁇ , where the sum ⁇ includes all chips of the PRN code used to modulate the weak signal w2.
  • the autocorrelation of a code with itself is 1 so the preceding equation can be rewritten as ⁇ Sl*Codel*Code2+w2 ⁇ . It can see that in order to obtain w2 Sl*Codel*Code2 is removed.
  • the code dependent portion of the crosscorrelation factor is computed from the known relative states of the PRN code generators to predict the crosscorrelation between a strong signal of unit power and zero frequency offset, and a weak signal. This factor is multiplied by the amplitude of the corresponding strong signal and adjusted for frequency attenuation before it is subtracted from the composite signal.
  • the various Gold codes used to modulate the PRN signals are all derived from a two code sequence Gl and G2 where the bits of the two code sequences are combined through an
  • Gold code selected. It is known that an XOR operation using binary numbers is mathematically equivalent to multiplication of ⁇ 1. This allows expressing the equations below in term of products of ⁇ 1 while in reality the implementation could be with binary numbers with XORs.
  • I Summation index ranges from 0 to 1022.
  • SatlGl(I) Value of satellite l's Gl coder chip at state I. Possible values are ⁇ 1.
  • SatlG2(I) Value of satellite l's G2 coder chip at state I. Possible values are ⁇ 1.
  • Sat2Gl(I) Value of satellite 2's Gl coder chip at state I. Possible values are ⁇ 1.
  • Sat2G2(I) Value of satellite 2's G2 coder chip at state I. Possible values are ⁇ 1.
  • offset time difference between the satellite 1 and 2 in units of chips ⁇ *Phase change per chip between satellite 1 and 2 in radians.
  • the 1023 states of Gl and G2 may be stored linearly in permanent memory. Thus, it is possible to quickly gather 8, 16, 32 or some other convenient number of bits with a single controller load instruction by computing the address of the desired chip and the shift required to align it. Thirty-two bits is a particularly convenient number because 31 divides 1023 evenly. If a single 1024 bit correlator match filter is employed, the 32 bits of the PN code are derived at a time from the G1/G2 states and loaded into a 1024 wide reference shift register. The current implementation thus reads 32 bits at a time and uses 31 of them at a time for each of 33 intervals that span the 1023 chips of the C/A code. The 31 bit sums are broken into four parts of 8, 8, 8, and 7 bits, and each 7 or 8 bit sum is multiplied by e "j ⁇ I where I changes by 7.75 chips for each part. The form of the sum is:
  • I Outer index ranges from 0 to 32
  • J Inner index ranges from 0 to 7 for the first three sums and from 0 to 6 for the last sum.
  • the inner sums are computed in parallel by using a 32 bit word that contains all 31 bits and using bitwise XOR to perform the multiplications and shifting and adding to sum the 1 bit products.
  • Note that all of the multiplications of the Gl and G2 codes in the above equation are implemented by bit- wise XOR instructions. The above algorithm is in error by at most -17 dB from an exact computation, and requires about 6000 controller operations to complete.
  • the code dependent crosscorrelation factors are computed for all strong and weak signal pairs with small frequency differences, i.e. frequency differences that could cause strong-weak crosscorrelation interference.
  • strong signals are those with C/N 0 >40 dB and weak signals are those with C/N 0 >30 dB.
  • the maximum "significant" frequency difference is 90Hz.
  • the code dependent cross correlation factor for each possibly interfering pair of signals is computed for each of the measurements that might potentially be used by the tracking and signal processing algorithms. For example, if early, punctual and late measurements are used by the tracking loops, the correlation factors for each of these code alignments is computed and stored in the tables.
  • ⁇ F Frequency difference between a strong and weak signal in Hz
  • Mod modulo offset to give a range of -500 Hz to +500 Hz
  • the attenuation only needs to be recomputed if the frequency difference changes by more than 5Hz.
  • phase and amplitude of the strong signal is required to remove the crosscorrelation.
  • the method used in the preferred embodiment is to track the strong signal on its own dedicated channel and collect the I, Q measurements output over the exact same interval that the weak signal I, Q samples are taken.
  • the known phase and frequency of the replica signal that is used to track the strong signal is an excellent approximation of the actual phase and frequency of the strong signal.
  • the magnitude of the I measurement provides a good approximation of the amplitude of the strong signal.
  • the bi-phase modulation of the strong signal data bits D may cause the phase of the strong signal to rotate 180 degrees whenever the data bits transition from a 1 to 0 or from a 0 to 1.
  • the phase of the strong signal is corrected by adding 180 degrees to the phase of the replica signal whenever the sign of the I measurement for the strong signal is negative.
  • SecondPhase SecondCorrelationPhase+DeltaPhase
  • FirstMag FirstCorrelationMag+FirstCodeOffsetFraction* Strongl *FrequencyAttentuation
  • SecondMag SecondCorrelationMag*(l -FirstCodeOffsetFraction) * Strong Frequency Attenuation
  • Co ⁇ rectedWeakIQ WeakIQ-FirstMag*e- jFirstPhase -SecondMag*e- jSecondphase
  • StrongDoppler Doppler of last output to the strong signals channel
  • ⁇ T Difference in time between outputs to the weak and strong channels
  • TableEntryOCodeState Code state difference of the first element of the crosscorrelation table.
  • WeakCarrierPhase Carrier phase angle of last output to the weak signal channel
  • StrongCarrierPhase Carrier phase angle of last output to the strong signal channel
  • DeltaKHz Nearest integer multiple of 1 KHz of the difference between the weak and strong channels Doppler. In units of KHz.
  • FirstCorrelationPhase Phase entry in the crosscorrelation table for the chip indicated by FirstCodeOffset
  • SecondCorrelationPhase Phase entry in the crosscorrelation table for the chip indicated by FirstCodeOffset +1 chip.
  • FirstCorrelationMag Magnitude entry in the crosscorrelation table for the chip indicated by FirstCodeOffset.
  • SecondCorrelationMag Magnitude entry in the crosscorrelation table for the chip indicated by FirstCodeOffset+1 chip.
  • CorrectedWeakIQ IQ correlation corrected for crosscorrelation from the strong signal.
  • CorrectedWeaklQ is computed for the early, on time, and late correlators by shifting the FirstCodeOffset appropriately, such as by half a chip each. These modified correlations are then used normally in the carrier and code tracking software for the weak signal. The algorithm attenuates the crosscorrelation by at least 10 dB without attenuating the weak signal, and is repeated for each strong signal that may be interfering with the weak signal.
  • FIG. 1 has described crosscorrelation to cancel a strong signal having a PRN from a weak signal having different PRN
  • the procedure may be modified to cancel a CW jamming signal and enhance a weak signal having a PRN.
  • FIG. 2 a signal-processing diagram for identifying and removing CW jamming signals where the cancelled signal of FIG. 1 may be a CW jamming signal is shown.
  • the receiver 200 receives a spread spectrum signals at antenna 202.
  • the crosscorrelator 204 is placed in a mode to identify CW jamming signals. In that mode, the crosscorrelator employs all ones for a PRN code.
  • the crosscorrelator 204 may have a signal processor 206 and a match filter 208 that despreads the spread spectrum signal.
  • the resultant signal is the CW jamming signal (the strong signal) and is tracked in the tracker 210.
  • An example of the tracker 210 in the current implementation may be a phase lock loop circuit.
  • the identified CW jamming signal is then used to generate a replica CW jamming signal 212.
  • the replica CW jamming signal may be created using a signal processor 214 and a match filter 216.
  • other approaches to generating a desired signal may be employed. Examples of other approaches include, but are not limited to voltage controlled oscillators, digital signal processing, analog signal processing.
  • the spread spectrum signal received by receiver 200 is then processed by a crosscorrelator 214 with dispreading codes rather than the all ones.
  • the received weak signal in the spread spectrum signal is demodulated by the signal processor in the crosscorrelator 218.
  • the generated CW jamming signal is canceled from the weak signal by a canceller 220.
  • the resultant signal is then tracked by a tracker 222.
  • the CW jamming signal that is being tracked by tracker 210 is further processed to remove the desired weak signal from the tracked CW jamming signal resulting in a clean replica of the unwanted signal on the demodulation process of the desired signal in block 224.
  • FIG. 3 a block diagram of electrical components of FIG. 2 is shown.
  • the spread spectrum signal containing the weak signal and the CW jamming signal are received at the receiver 200 via antenna 202.
  • the spread spectrum signal is demodulated and the CW jammer signal is filtered by the jammer filter 302.
  • the resulting CW jamming signal is tracked by jammer tracker 304.
  • the tracked jamming signal is then replicated by a jammer replica wave generator 306 as a replicated CW jamming signal.
  • the CW signal has the characteristic of a constant phase, therefore the replicated CW jamming signal is scaled and rotated 308 to an appropriate phase to be subtracted from the demodulated weak signal.
  • the weak signal is demodulated by a demodulator 310.
  • the phase and magnitude replicated CW jamming signal is then subtracted from the weak signal from the demodulator 302 by a signal canceller 312.
  • the resulting weak signal is then tracked by a track control circuit 314.
  • the track control circuit 314 outputs the weak signal to the demodulator 310 and two signal combiners 316 and 318.
  • the weak signal is subtracted from the CW jammer signal by the signal combiner 316 and the resulting signal is used to scale and rotate the replicated CW jamming signal.
  • the weak signal is subtracted from the CW jamming signal by signal combiner 318 in order to provide a more accurate CW jamming signal to be replicated by the jammer replica wave generator 306.
  • FIG. 4 a flow diagram 400 of the identifying and removing CW jamming signals is shown.
  • the procedure starts 402 with a receiver 200 receiving a spread spectrum signal 404.
  • the signal may be filtered and the CW jamming signal is identified 406 using a crosscorrelator.
  • the tracked CW jamming signal is then replicated 410 by a jammer replica wave generator 306.
  • the replicated CW jammer signal is then subtracted from the received signal 412.
  • the CW jamming signal has been removed from the received signal and processing is complete 414.

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Position Fixing By Use Of Radio Waves (AREA)

Abstract

L'invention concerne un récepteur pouvant recevoir un signal à étalement du spectre et ayant un cross-corrélateur qui permet d'identifier, de suivre, de reproduire le brouillage d'une onde porteuse (CW) et de l'enlever du signal à étalement du spectre reçu une fois un faible signal démodulé.
PCT/US2004/035350 2003-10-20 2004-10-20 Enlevement par cross-correlation de signaux de brouillage intentionnel d'ondes porteuses WO2005040848A1 (fr)

Applications Claiming Priority (10)

Application Number Priority Date Filing Date Title
US10/689,565 2003-10-20
US10/689,565 US7822105B2 (en) 2003-09-02 2003-10-20 Cross-correlation removal of carrier wave jamming signals
US54738504P 2004-02-23 2004-02-23
US54681604P 2004-02-23 2004-02-23
US60/546,816 2004-02-23
US60/547,385 2004-02-23
USPCT/US04/28542 2004-09-02
PCT/US2004/028542 WO2005022187A2 (fr) 2003-09-02 2004-09-02 Commande et caracteristiques pour recepteurs de systemes de positionnement pour satellite
USPCT/US04/28926 2004-09-02
PCT/US2004/028926 WO2005047923A2 (fr) 2003-09-02 2004-09-02 Systeme de traitement de signaux de positionnement de satellites

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Publication Number Publication Date
WO2005040848A1 true WO2005040848A1 (fr) 2005-05-06

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Cited By (4)

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Publication number Priority date Publication date Assignee Title
WO2009158049A1 (fr) * 2008-06-27 2009-12-30 Sirf Technology, Inc. Procédé et appareil pouvant atténuer les effets d'une interférence par ondes entretenues au moyen d'un traitement de post-corrélation dans un récepteur gps
CN103954977A (zh) * 2014-05-12 2014-07-30 武汉大学 一种gnss欺骗干扰感知方法和系统
EP2930536A3 (fr) * 2014-04-09 2015-10-28 The Mitre Corporation Positionnement, navigation et dispositif de synchronisation d'interférence et détecteur de mystification avec atténuation de synchronisation
CN112180407A (zh) * 2020-09-14 2021-01-05 北京宏德信智源信息技术有限公司 一种强弱信号相互干扰的消除方法

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Publication number Priority date Publication date Assignee Title
EP0884855A1 (fr) * 1996-11-29 1998-12-16 Mitsubishi Denki Kabushiki Kaisha Dispositif eliminant une onde partagee
WO2000055992A1 (fr) * 1999-03-17 2000-09-21 Ericsson, Inc. Procede de recherche cellulaire et de synchronisation ainsi qu'appareil pour communication sans fil
US6282231B1 (en) * 1999-12-14 2001-08-28 Sirf Technology, Inc. Strong signal cancellation to enhance processing of weak spread spectrum signal

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0884855A1 (fr) * 1996-11-29 1998-12-16 Mitsubishi Denki Kabushiki Kaisha Dispositif eliminant une onde partagee
WO2000055992A1 (fr) * 1999-03-17 2000-09-21 Ericsson, Inc. Procede de recherche cellulaire et de synchronisation ainsi qu'appareil pour communication sans fil
US6282231B1 (en) * 1999-12-14 2001-08-28 Sirf Technology, Inc. Strong signal cancellation to enhance processing of weak spread spectrum signal

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009158049A1 (fr) * 2008-06-27 2009-12-30 Sirf Technology, Inc. Procédé et appareil pouvant atténuer les effets d'une interférence par ondes entretenues au moyen d'un traitement de post-corrélation dans un récepteur gps
GB2473792A (en) * 2008-06-27 2011-03-23 Sirf Tech Inc Method and apparatus for mitigating the effects of cw interference via post correlation processing in a GPS receiver
GB2473792B (en) * 2008-06-27 2012-11-07 Sirf Tech Inc Method and apparatus for mitigating the effects of cw interference via post correlation processing in a GPS receiver
EP2930536A3 (fr) * 2014-04-09 2015-10-28 The Mitre Corporation Positionnement, navigation et dispositif de synchronisation d'interférence et détecteur de mystification avec atténuation de synchronisation
US10509130B2 (en) 2014-04-09 2019-12-17 The Mitre Corporation Positioning, navigation, and timing device interference and spoofing detector with timing mitigation
CN103954977A (zh) * 2014-05-12 2014-07-30 武汉大学 一种gnss欺骗干扰感知方法和系统
CN112180407A (zh) * 2020-09-14 2021-01-05 北京宏德信智源信息技术有限公司 一种强弱信号相互干扰的消除方法

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