WO2004029646A2 - Detection et compensation de puissance faible pour systemes satellites - Google Patents

Detection et compensation de puissance faible pour systemes satellites Download PDF

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Publication number
WO2004029646A2
WO2004029646A2 PCT/US2003/030050 US0330050W WO2004029646A2 WO 2004029646 A2 WO2004029646 A2 WO 2004029646A2 US 0330050 W US0330050 W US 0330050W WO 2004029646 A2 WO2004029646 A2 WO 2004029646A2
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WIPO (PCT)
Prior art keywords
signal
noise ratio
band power
error
low
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PCT/US2003/030050
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English (en)
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WO2004029646A3 (fr
Inventor
Mats A. Brenner
Original Assignee
Honeywell International 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 US10/667,854 external-priority patent/US6809684B2/en
Priority claimed from US10/667,628 external-priority patent/US7242347B2/en
Priority claimed from US10/667,830 external-priority patent/US7555262B2/en
Priority claimed from US10/668,011 external-priority patent/US6888498B2/en
Application filed by Honeywell International Inc. filed Critical Honeywell International Inc.
Priority to AU2003278884A priority Critical patent/AU2003278884A1/en
Priority to EP03770399.8A priority patent/EP1573354B1/fr
Publication of WO2004029646A2 publication Critical patent/WO2004029646A2/fr
Publication of WO2004029646A3 publication Critical patent/WO2004029646A3/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
    • G01S19/03—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
    • G01S19/07—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers providing data for correcting measured positioning data, e.g. DGPS [differential GPS] or ionosphere corrections
    • G01S19/071—DGPS corrections
    • 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
    • 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
    • G01S19/03—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
    • G01S19/08—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers providing integrity information, e.g. health of satellites or quality of ephemeris data
    • 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
    • G01S19/20—Integrity monitoring, fault detection or fault isolation of space segment
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
    • H04B7/084—Equal gain combining, only phase adjustments
    • 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
    • G01S19/29—Acquisition or tracking or demodulation of signals transmitted by the system carrier including Doppler, related
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • the present invention relates generally to satellite navigational systems, and more particularly, relates to measuring the accuracy of navigational variables.
  • a global positioning system measures the three-dimensional, global position of a radio receiver, using the distances between the radio receiver and a number of earth- orbiting satellite transmitters.
  • the receiver usually mounted to a vehicle such as a commercial passenger aircraft, receives signals from the satellite transmitters. Each signal indicates both the position of its transmitter and its transmission time, enabling the receiver, equipped with its own clock, to approximate signal transit times and to estimate the distances to the transmitters.
  • a processor coupled to the receiver uses at least four of these distances, known as pseudoranges, to approximate or estimate the position of the receiver and the associated vehicle. The accuracy of these estimates, or position solutions, depends on a number of factors, for example, changing atmospheric conditions and performance of individual satellite transmitters.
  • GPSs global positioning systems
  • DCP ground-based differential correction processor
  • the FAA initiated a program to develop requirements for developing and deploying such a navigational system known as the GPS-based Local- Area- Augmentation Systems, or GPS-based LAASs.
  • the FAA released Specification, FAA-E-2937A (April 17, 2002), which establishes the performance requirements for a Category I Local Ground Facility (LGF) in the LAAS system.
  • LGF Local Ground Facility
  • the contents of FAA-E-2937A are incorporated herein by reference.
  • the LGF will monitor the satellite constellation, provide the LAAS corrections and integrity data, and provide approach data to and interface with air traffic control.
  • the LAAS uses a differential global positioning system (DGPS).
  • the DGPS includes a global positioning system (GPS) and at least one ground station.
  • the GPS uses a number of orbiting position transmitting satellite stations and a receiver on an aircraft to determine the position of the aircraft with respect to ground.
  • the receiver can determine the position, speed, and altitude of the aircraft.
  • the DGPS can correct errors that may occur in the transmission of data from the satellites to the receiver. As a result the DGPS can determine the position of the aircraft with a high degree of accuracy.
  • the ground-based GPS receivers each with a known position, work as normal GPS receivers in determining respective sets of pseudoranges based on signals from at least four earth-orbiting satellite transmitters. These pseudoranges are fed to the ground-based DCP, which uses them and the known positions of the ground receivers to determine correction data.
  • the correction-data transmitter then transmits to aircraft approaching the landing area. These approaching aircraft use the correction data to correct position estimates of on-board GPS receivers, providing better position solutions than possible using their on-board GPS receivers alone.
  • the position estimates are required to stay within minimum accuracy limits known as vertical and lateral alert limits. Failure to stay within accuracy limits causes issuance of an alert, signaling a pilot to abort the automatic landing and to restart the landing process.
  • accuracy is of paramount importance. However, as in all navigational systems, a certain amount of error will inevitably exist. This error must be prepared for, monitored, and dealt with.
  • One potential source of error identified in the LGF specification is low signal power, whether in the satellite signals received by the LGS or in the satellite and ground signals received by the aircraft.
  • error bound also referred to as the "protection limit” or "integrity limit.”
  • the error bound reflects a range of values within which - to a predetermined confidence level set by regulations or by industry standards - the aircraft is likely to be located.
  • a low-power error system for detecting a low-power condition in a navigational system and adjusting the error bound to compensate for the low-power condition.
  • the system includes a first detector for detecting wide band power and a second detector for detecting narrow band power, and a processor.
  • the processor includes logic for computing the signal-to-noise ratio and logic for adjusting the error bound based on the signal-to-noise ratio.
  • the logic for computing the signal-to-noise ratio may include logic for computing a lower confidence limit for the signal- to-noise ratio.
  • Fig. 1 is a flow diagram illustrating the detection of a low-power error condition.
  • Fig. 2 is a block diagram of a LAASsystem.
  • Fig. 3 is a block diagram of a low-power error system according to an exemplary embodiment.
  • a low-power error system for detecting a low power condition may be employed in a variety of satellite navigation systems but is preferably implemented in a LAAS system using DGPS. As illustrated in Fig. 3, the low-power error system may be implemented in a LGF, but it may equally well be used in an aircraft using the LAAS system.
  • the navigational signal received by the system from at least one of the GPS satellites (or, where the system is located in an aircraft, from the LGF) is weak relative to the noise level.
  • a low power condition may be caused either because the signal itself is weak (e.g., where the satellite signal has been blocked or deflected by atmospheric or terrestrial conditions) or because the level of ambient noise is high (e.g., interference from terrestrial radio transmissions), or a combination of the two.
  • a low power condition is characterized by the signal-to-noise ratio ("S/No") of the navigational signal. Where the signal has a low power, or the level of noise is high, the S/No is relatively low. ⁇
  • a method for detecting and compensating for low- power conditions.
  • the system receives a satellite radio signal and uses the signal to determine a navigational measurement, such as position, velocity, acceleration, time, or other measurement.
  • the system measures narrow band power and wide band power around the frequency of the satellite radio signal, and it calculates in real time an estimate of the signal-to-noise ratio based on the narrow band and wide band power.
  • system may use a lower confidence limit as its estimate of the signal-to-noise ratio.
  • the lower confidence limit is calculated by determining the signal-to-noise ratio from the narrow band and wide band power and then subtracting a confidence offset from the result.
  • the system determines the component of error in the navigational measurement that is attributable to thermal and broadband white noise. That error component is combined with other error components to determine the total error, and the system determines whether the error bound for the navigational measurement has been exceeded.
  • a LAAS system receives a satellite navigation signal at step 10 and calculates a navigational measurement (step 12) in response to the signal.
  • the signal is received from a GPS satellite.
  • the system also detects one or more observable variables and calculates the signal-to-noise ratio based on the values of the observable variables.
  • the observable variables are measured on a periodic basis to provide real-time monitoring of the signal-to-noise ratio.
  • the logic estimates the signal-to-noise ratio based on an algorithm or mathematical function denoted f snr , as follows:
  • the observable variables are the narrow band power and the wide band power of the satellite navigation signal received by a GPS receiver at the LAAS system.
  • the system detects P n , the narrow band power (step 14) and P w , the average wide band power (step 16).
  • the wide band power P w is measured as an average over the time interval T, which preferably remains constant at 1ms.
  • the narrow band power P n is preferably measured as an average over a period that is M times as long as period T.
  • M is equal to 20.
  • the system calculates the signal-to-noise ratio in real time based on the measurements of P n and P w , together with the values of the constants T and M, according to the following formula:
  • the signal-to-noise ratios given by the above formulae express the result in decibels, according to normal engineering practice. It should be noted that the result need not be expressed in decibels (for example, the operator 10 log ⁇ 0 [ . . .] may be omitted) so long as future calculations are adjusted accordingly.
  • the system calculates the signal-to-noise ratio as an average over several samples, where K is the number of samples, each one having a duration T s equal to MT.
  • the average is taken by averaging the observables themselves (such as P n and P w ) over the K samples before calculating the signal-to-noise ratio.
  • the system may average the narrow band power at step 18 and average the wide band power at step 20 before calculating the signal-to-noise ratio at step 22.
  • the averaging may take place at any other point in the process, for example by calculating S/No for each sample and averaging the result over the K samples to obtain an average S/No.
  • the estimate of the signal-to-noise ratio becomes more accurate with more samples K.
  • the estimate of the signal-to- noise ratio may be adjusted to a lower confidence limit (step 24) to reduce the likelihood that a the estimate of the signal-to-noise ratio will be unduly low and will result in unwarranted confidence in the navigational measurement.
  • the system may be used to determine any of a number of navigational measurements such as position, velocity, acceleration, or time, or other measurements.
  • the value of one of these navigational measurements is designated herein by the variable A.
  • the error in the value of A is represented by a sigma value O , where a 1- sigma OA represents one standard deviation in the measured value of A.
  • the 1-sigma ⁇ A has several components reflecting all error sources in the satellite signal and signal tracking system. One of these components is the component ⁇ w , which reflects the impact of thermal and broadband white noise.
  • the components of the error are additive in their squares, so that the total ⁇ A from wideband noise and other sources may be calculated as follows:
  • the system uses the estimate of the signal-to-noise ratio obtained as described in section II.A, above, to calculate the error contribution ⁇ w from wide band sources (step 26).
  • the system calculates the error contribution with a function of the following format:
  • the error contribution is calculated to the first order according to the following formula:
  • step 28 the system sums the value of ⁇ w with other error contributions (step 28) to calculates the error bound for the measurement of A. If the error bound for A falls outside of an alert limit (step 30), such as a limit set by FAA regulations or industry practice, the system may issue an alert (step 32). Such an alert could, for example, direct a pilot to abort a landing attempt or to rely on different navigational aids during the landing. Otherwise, the navigational measurement calculated in step 12 may be reported to the pilot (step 34).
  • an alert limit such as a limit set by FAA regulations or industry practice
  • the estimate of the signal-to-noise ratio S/No may include errors caused at least in part by the finite sample size.
  • the actual signal-to-noise ratio differs from the estimated signal-to-noise ratio by a deviation dS/No.
  • the system may overbound the error by adjusting the signal-to-noise ratio estimate to a lower confidence limit S/No_low_lim (step 24).
  • a lower confidence limit S/No_low_lim the system determines the lower confidence limit S/No_low_lim by subtracting a confidence offset dS/No_low from the signal-to-noise ratio estimate S/No.
  • the lower confidence limit S/No_low_lim is no greater than the actual signal-to-noise ratio.
  • the probability of this occurring is expressed as P(dS/No >-dS/No_low), or P ⁇ , m .
  • the value of the confidence offset dS/No_low is set by determining an acceptable probability P ⁇ , m that the error ⁇ w will be correct (i.e., that it will not be underestimated), and then determining what value of the confidence offset dS/No_low is required to achieve that probability.
  • the probability p ⁇ , m represents the limit on the probability per time interval KT S that the error ⁇ w (as calculated from the estimated signal-to-noise ratio) is incorrect.
  • the value of p ⁇ ,m is determined in advance by regulations or industry standards governing the integrity allocated to the particular type of fault expressed as a probability per unit of time. Such regulations may indicate, for example, that p ⁇ ⁇ m may be no greater than 10 "7 /150 seconds.
  • a confidence offset is calculated so that the acceptable value of P ⁇ ⁇ m will be obtained.
  • One technique for calculating the confidence offset makes use of the probability distribution of dS/No.
  • the deviation dS/No of the actual signal-to-noise ratio from the value S/No has a probability distribution represented by the probability density function pdf(x), where x represents all possible deviations dS/No.
  • the function pdf(x) can be derived from the equation for ⁇ w , such as Equations 3 or 4, above.
  • the confidence offset dS/No_low is determined by solving Equation 9 for dS/No_low:
  • the system calculates the lower confidence limit (step 24) by subtracting the confidence offset dS/No_low from the estimated value of S/No.
  • the system uses the lower confidence limit as the signal-to-noise ratio in calculating the error (step 26).
  • the system uses the value of S/No_low_lim to calculate the value of ⁇ w according to the equation:
  • the system for detecting a low-power condition is implemented in a LAAS system, which augments a differential global positioning satellite (DGPS) system.
  • a LAAS system such as the system 100 illustrated in Fig. 2, includes a plurality of satellites 102 and a LAAS Ground Facility (LGF) 200.
  • LGF LAAS Ground Facility
  • the LAAS system provides precision approach data and landing capability to an aircraft 104.
  • the plurality of satellites 102 provides the aircraft 104 and the LGF 200 with GPS ranging signals and orbital parameters.
  • the LGF 200 receives the satellite signals through at least one reference receiver 202, a DGPS cabinet 204, and at least one VDB cabinet 206.
  • the LGF 200 provides differential corrections, integrity parameters, and precision approach pathpoint data to the aircraft 104 by way of the VDB cabinet 206.
  • Communication between the LGF and the aircraft 104 is conducted using Very High Frequency (VHF) Data Broadcast (VDB).
  • VHF Very High Frequency
  • VDB Very High Frequency Data Broadcast
  • the aircraft 104 may apply the LGF corrections to the GPS ranging signals to accurately determine its position.
  • a system 300 for detecting a low-power condition includes a signal-to-noise ratio module ("SNR module") 302 for calculating the signal-to- noise ratio of a navigational signal.
  • a narrow band detector 304 determines the narrow band power P n
  • a wide band detector 306 determines the average wide band power P w .
  • the SNR module includes S/No logic 314 for estimating the signal-to-noise ratio S/No based at least in part on the narrow band and wide band power, as described in section II.
  • the detectors 304 and 306 provide measurements on a periodic basis to enable real-time monitoring of the signal-to-noise ratio.
  • Confidence limit logic 312 in the SNR module calculates the lower confidence limit from the estimated value of S/No as described in section II.C, above.
  • a low-power error module 308 receives the lower confidence limit and calculates the 1-sigma error ⁇ w attributable to wide band and thermal noise, as described in section II.B, above.
  • a total error module 309 receives the error ⁇ w and error contributions calculated from other sources (not illustrated) and sums the errors as described in section II.B to determine a total error. The total error and/or the low power error ⁇ w is reported to an LGF processor 310.
  • Alert logic 313 in the LGF processor detects whether the total error has exceeded an error bound and issues an alert.
  • the alert may be transmitted to the aircraft 104 by the VDB cabinet 206 (Fig. 2).
  • the functions of each of the modules of the error compensation system may be implemented in a combination of software, firmware, and/or hardware.
  • the system 300 may be implemented by executable instructions stored in a computer memory and executed by a processor.
  • the system is software based and may be stored and executed in the DGPS Cabinet 204 (Fig. 2).
  • the components of the system 300 may be implemented by software.

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Security & Cryptography (AREA)
  • Signal Processing (AREA)
  • Position Fixing By Use Of Radio Waves (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)

Abstract

L'invention concerne un système destiné à détecter des conditions d'erreur de faible puissance dans un système d'augmentation local (LAAS). Ledit système reçoit un signal radio d'un système mondial de localisation (GPS) satellite et mesure la puissance de bande large et de bande étroite du signal radio en temps réel. Ledit système estime le rapport signal sur bruit en temps réel sur la base de mesures moyennes de bande large et de bande étroite. Un rapport signal sur bruit faible indique des états de puissance faibles. Le système calcule alors une contribution d'erreurs provoquées par des états de puissance faible, et additionne la contribution d'erreurs avec d'autres contributions d'erreurs, de façon à déterminer l'erreur totale dans une mesure de navigation. Afin d'assurer la surdélimitation d'erreurs, le système peut soustraire une sortie de confiance du rapport signal sur bruit, ce qui permet d'obtenir une limite de confiance inférieure.
PCT/US2003/030050 2002-09-24 2003-09-24 Detection et compensation de puissance faible pour systemes satellites WO2004029646A2 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU2003278884A AU2003278884A1 (en) 2002-09-24 2003-09-24 Low power detection and compensation for satellite systems
EP03770399.8A EP1573354B1 (fr) 2002-09-24 2003-09-24 Detection et compensation de puissance faible pour systemes satellites

Applications Claiming Priority (12)

Application Number Priority Date Filing Date Title
US41325102P 2002-09-24 2002-09-24
US41308002P 2002-09-24 2002-09-24
US41325202P 2002-09-24 2002-09-24
US41321102P 2002-09-24 2002-09-24
US60/413,211 2002-09-24
US60/413,080 2002-09-24
US60/413,251 2002-09-24
US60/413,252 2002-09-24
US10/667,854 US6809684B2 (en) 2002-09-24 2003-09-22 Signal deformation monitor
US10/667,628 US7242347B2 (en) 2002-09-24 2003-09-22 Low power detection and compensation for satellite systems
US10/667,830 US7555262B2 (en) 2002-09-24 2003-09-22 Radio frequency interference monitor
US10/668,011 US6888498B2 (en) 2002-09-24 2003-09-22 Method and system for compensating satellite signals

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WO2004029646A2 true WO2004029646A2 (fr) 2004-04-08
WO2004029646A3 WO2004029646A3 (fr) 2004-07-15

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PCT/US2003/030050 WO2004029646A2 (fr) 2002-09-24 2003-09-24 Detection et compensation de puissance faible pour systemes satellites
PCT/US2003/029956 WO2004031797A1 (fr) 2002-09-24 2003-09-24 Appareil de suivi d'interference de frequences radio
PCT/US2003/029955 WO2004031799A1 (fr) 2002-09-24 2003-09-24 Appareil de suivi de deformation de signal
PCT/US2003/029608 WO2004030237A2 (fr) 2002-09-24 2003-09-24 Procede et systeme de correction de signaux transmis par satellite

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PCT/US2003/029956 WO2004031797A1 (fr) 2002-09-24 2003-09-24 Appareil de suivi d'interference de frequences radio
PCT/US2003/029955 WO2004031799A1 (fr) 2002-09-24 2003-09-24 Appareil de suivi de deformation de signal
PCT/US2003/029608 WO2004030237A2 (fr) 2002-09-24 2003-09-24 Procede et systeme de correction de signaux transmis par satellite

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EP (1) EP1782550A2 (fr)
AU (4) AU2003273352A1 (fr)
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EP1782550A2 (fr) 2007-05-09
AU2003273352A1 (en) 2004-04-23
WO2004029646A3 (fr) 2004-07-15
WO2004030237A3 (fr) 2004-06-10
AU2003272597A1 (en) 2004-04-19
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AU2003278884A1 (en) 2004-04-19
WO2004031797A1 (fr) 2004-04-15

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