RU2574333C2 - Method and system for watch correction - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: satellite clock error is defined for every navigation satellite on the basis of measurements of pseudorange code, carrier and broadcast errors of satellite clock supported by the network of receivers (S402). Differences are defined between calculated satellite clock errors and broadcast errors for every satellite (S406). Reference clock satellite is selected for every group navigation satellites. Note here that reference clock satellite features the difference in clock errors for this satellite group (S408). Correction is defined for broadcast clock error by application of the reference satellite clock error function to broadcast error for every satellite of one or more satellite groups (S410).

EFFECT: perfected determination of clocks correction at every network receiver.

25 cl, 6 dwg

Description

This application claims priority based on provisional patent application US No. 61/432646, filed January 14, 2011, under the name METHOD AND SYSTEM FOR DETERMINING CLOCK CORRECTIONS, according to 35 U.S.C. 119 (e).

FIELD OF THE INVENTION

This invention relates to a method and system for determining clock corrections for a satellite navigation system.

State of the art

A location receiver, such as a Global Navigation Satellite System (GNSS) receiver, can estimate the position and speed of an object or vehicle.

The location receiver may output inaccurate positions and speeds due to inaccuracy of the clock data from one or more satellites. GNSS augmentation systems, which distribute corrections for GNSS errors, provide user receivers with information that provides more accurate navigation than is possible otherwise. Such augmentation systems typically include corrections to the clock and orbit in the transmitted information of the clock and orbit of the satellite.

The GNSS Augmentation System typically includes a network of receivers at known locations. These receivers transmit information to a processing center where information is combined and GNSS corrections are calculated. Since each receiver in the network of the augmentation system usually has its own local clock, which is not synchronized with other clocks in the network, it is necessary to have a single source of time with which all information from network receivers can be checked.

According to a prior art approach, on one or more network receivers, an accurate clock (typically an atomic clock external to the network receiver) is used to supply timing signals to the network receiver. Such a network receiver, therefore, has a very stable time standard, and this network receiver can be used as a single source of time with which information from other network receivers can be checked. Due to the possible failure of the exact clock or the failure of the communication lines between this network receiver and the processing center, a few exact clocks are usually set to increase the reliability of the system. The performance of this exact watch is usually evaluated and monitored in real time to facilitate switching between the exact watch.

In practice, this prior art approach requires the installation of expensive atomic clocks in several different places with network receivers. Thus, there is a need for an improved, economical method and system for determining clock corrections for a satellite navigation system. In particular, there is a need for a method and system for determining clock corrections that do not require accurate clocks on any network receiver.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the invention, a method and system for determining satellite clock corrections facilitates the determination of accurate position estimates by one or more mobile positioning receivers. The method and system comprise collecting pseudo-range code measurements, carrier phase measurements and navigation message data (e.g., broadcast clock error data or broadcast clock deviation) from a network of stationary satellite signal receivers transmitted by one or more orbital constellations of navigation satellites. At each time interval (for example, an epoch), the error of the clock is calculated for each navigation satellite based on the collected measurements of the pseudo-range code, measurements of the carrier phase and data of the navigation message. Clock error differences are formed between the calculated satellite clock error and the broadcast clock error for each satellite. For each orbital constellation, a satellite of the reference clock is selected from the navigation satellites in this orbital constellation, which has a median value of the difference of clock errors for this orbital constellation of satellites. Then, the correction of the broadcast error of the clock of each satellite in this orbital group is determined by summing the function of the clock error of the satellite of the reference clock with the broadcast clock error for each satellite in this orbital group (for example, on a satellite basis in each orbital group). The correction value in each epoch or other time interval (for example, several eras) is limited based on the control parameter limit (for example, where the control parameter limit is less than or approximately equal to the satellite clock error of the reference clock or where the control parameter limit contains a fixed parameter, expressed in units of distance , since the solution of the Kalman filter converges on the solution for the broadcast clock error).

Brief Description of the Drawings

FIG. 1 is a block diagram of a first embodiment of a system for determining clock corrections.

FIG. 2 is a block diagram of a second embodiment of a system for determining clock corrections.

FIG. 3 is a block diagram of a mobile location receiver in accordance with the system shown in FIG. 1 or FIG. 2.

FIG. 4 is a first example flowchart of a method for determining clock error corrections in accordance with any embodiment of the system.

FIG. 5 is a second example of a flowchart of a method for determining clock error corrections in accordance with any embodiment of the system.

FIG. 6 is a flowchart of a method for determining a position estimate or a speed estimate at a receiver that receives clock error corrections.

Description of a preferred embodiment of the invention

In accordance with one embodiment of a system 11 for determining clock corrections for a satellite navigation system (eg, GNSS), system 11 facilitates real-time determination of accurate and smooth corrections of satellite clocks recorded in broadcast satellite clock error data to support increased reliability and accuracy of mobile positioning receivers 42 that can use real-time clock correction data 44. The method and system generates clock correction data 44 (for example, clock error correction) that is well suited to provide increased accuracy and resolution when determining the position or speed of the mobile location receiver 42 or corresponding object in real time.

In one embodiment, system 11 comprises a receiver network 15 that is capable of communicating with a central electronic data processing system 16 via one or more communication lines 13. The central electronic data processing system 16 is connected to a satellite-based ground communication device 38 that facilitates transmitting clock correction data 44 or other correction data (e.g., position correction data) to one or more mobile positioning receivers 42 via a remote satellite communication device 40 (e.g. satellite vehicle) in orbit above the surface of the earth. The mobile location receiver 42 is connected to a correction transmission device 41 (e.g., a satellite correction receiver) that is capable of receiving satellite signals (e.g., clock correction data 44) from the remote satellite communications device 40. Although FIG. 1 illustrates a satellite-based ground communication device 38, a remote satellite communication device 40, and a correction transmission device 41 for transmitting or distributing correction data, correction data or correction may be distributed in any other way by electronic means of communication, telecommunications, electromagnetic signals or wireless communications.

In one embodiment, the receiver network 15 comprises from a first reference station 10 through an Nth reference station 14, where N is any positive integer or an integer greater than 2. As shown in FIG. 1, the receiver network 15 comprises a first reference station 10, a second reference station 12, and a third reference station when N is, for example, three. In one embodiment, the receiver network 15 may comprise reference stations (10, 12, and 14) that are globally distributed at different known locations (e.g., geographic coordinates of the station), although regional or local distribution of reference stations is possible (10, 12, and 14).

Each reference station (10, 12, and 14) comprises a reference receiver 51 at a corresponding known or fixed location, a reference electronic data processing system 53, and a transmitter or transceiver 55. Each reference receiver 51 receives or detects one or more of the following: (1) measurements or pseudo-range code data, (2) measurements or carrier phase data, (3) broadcast satellite clock error data, (4) ephemeris data and (5) other navigation reference data. The reference receiver 51 may receive satellite signals carrying signals and encoded signals from one or more satellites of the Global Positioning System (GPS), from one or more satellites of the Global Navigation Satellite System (GLONASS), or satellites of both systems.

The receiver data processing system 53 may store, retrieve, and process navigation reference data associated with received satellite signals, carrier signals, and encoded signals. In one embodiment, the transmitter or transceiver 55 of each reference station (10, 12 or 14) transmits one or more of the following data to the central electronic data processing system 16 or computer hub via one or more communication lines 13: (1) measurements or pseudorange data code, (2) measurements or carrier phase data, (3) broadcast satellite clock error data, (4) ephemeris data, (5) reference navigation data, and (6) derived data obtained by analysis or processing of any of the above s data items. For example, the above-described transmitted data may relate to the first orbital constellation of navigation satellites (for example, Global Positioning System (GPS) satellites), the second orbital constellation of satellites (for example, GLONASS satellites) or both.

The reference navigation data may contain one or more of the following data elements: (a) the corresponding location or geographical coordinates of the reference station of each respective reference station (10, 12 or 14), (b) the corresponding geographical coordinates of the antennas of each reference receiver 51, (c) the corresponding reference station identifier of each reference station (10, 12 or 14) and (d) satellite identifiers for the respective satellites that provide the corresponding broadcast clock error data and the corresponding relevant ephemeris data.

Communication lines 13 support real-time data transmission between the reference station (10, 12 or 14) and the central electronic data processing system 16. Communication lines 13 may contain one or more of the following: packet data networks, data networks, virtual private networks, Internet data channels, telecommunications equipment, optical communications equipment, radio communications equipment, microwave communications equipment, fiber optic communications lines, lines point-to-point microwave communication, dedicated wired connection, multi-core cable, coaxial cable communication line, optical communication line, communication line or other suitable communication lines for real-time data transmission Name.

The measurements or pseudo-range code data may be decoded by the reference receiver 51 from information that modulates or encodes satellite signals received by each reference receiver 51.

The carrier phase measurement data may come from a phase measurement device in a reference receiver 51, which receives one or more carrier signals or data, for example, from a high frequency receiver stage. In one embodiment, the phase measuring device may provide carrier phase measurements for GPS carrier signals, GLONASS carrier signals, or carrier signals of both systems.

Ephemeris data contains information about the orbiting satellite or a set of data on the positions of satellites relative to one or more reference positions on or near the surface of the earth according to a schedule. Ephemeris data may be stored in a database or in one or more files. Satellites can transmit ephemeris data in a navigation message that can be received by the reference receiver 51.

In an alternative embodiment, the reference receiver 51 detects carrier phase data or carrier phase measurements associated with one or more carrier signals; the reference data processing system 53 at the reference station (10, 12 or 14) determines an initial carrier phase uncertainty solution or a carrier phase uncertainty solution set for multiple satellite signals received at the reference receiver 51. The reference data processing system 53 receives the carrier phase data, and the initial uncertainty solution corrects them using a known or fixed location of the reference receiver 51 to determine an extended uncertainty solution. In one example, the adjusted carrier phase data comprises an estimated carrier phase and an extended uncertainty solution or other data derived from them. In turn, the adjusted carrier phase data or other correction data is transmitted via a wireless signal or an electromagnetic signal to the central data processing system 16.

In one embodiment, the central electronic data processing system 16 comprises a central hub of one or more computers. The central electronic data processing system 16 comprises a data processor 18, a data storage device 22, and a communication interface 36 that are connected to the data bus 20. The data processor 18 may comprise a microprocessor, a controller, a matrix of programmable logic devices, a specialized integrated circuit, an arithmetic logic device, or other device suitable for processing data, performing mathematical operations on data, or performing Boolean logic or arithmetic logic on data. The data storage device 22 may include electronic memory, optical storage device, magnetic storage device or other device capable of storing and retrieving data. As shown in FIG. 1, data storage device 22 stores, maintains, or interacts with one or more of the following modules: data acquisition module 24, parameter estimation module 26, main predictive filter 27, clock difference difference module 28, reference satellite selection module 30, clock correction module 32 and communication module 34. Any of the above modules (24, 26, 27, 28, 30, 32 and 34) in the data storage device 22 may comprise a software module, an electronic module, software instructions, or a hardware or electronic module for implementing equivalent software instructions. If any of the above modules contains program instructions or programs, these program instructions or programs implemented by software may be stored in the data storage device 22, on optical media, magnetic media, or other medium that is non-volatile or substantially permanent.

In one embodiment, the data acquisition module 24 provides program instructions or is capable of collecting, organizing, and monitoring processing of measurements or pseudo-range code data, measurements or carrier phase data and navigation message data (for example, including ephemeris and broadcast satellite clock error data) received by a network of 15 receivers that receive signals at multiple frequencies transmitted by one or more orbital constellations of navigation satellites. The orbital constellation of navigation satellites may mean the orbital constellation of GPS, the orbital constellation of GLONASS, or, for example, other orbital constellations. In one embodiment, the data collection module 24 tracks the above information in a database, spreadsheet, file (e.g., inverted file), or other data structure that allows you to identify, organize, or sort reference data using a reference station identifier or geographical coordinates of a reference station ( 10, 12, 14).

The parameter estimating module 26 provides program instructions or is capable of calculating or determining the calculated satellite clock error data (for example, clock status data) on a per-unit basis for each satellite based on measurements or pseudorange code data, measurements or carrier phase data corresponding to known reference locations stations (or reference receivers) and broadcast satellite clock error data. In one configuration, the parameter estimator 26 may calculate or determine a computed satellite clock error based on navigation message data (for example, which include broadcast satellite clock error data) in addition to measurements or pseudo-range code data, measurements or carrier phase data corresponding to known reference locations stations (or reference receivers). In one embodiment, the parameter estimator 26 may comprise, use, or access one or more of the following: a central orbit estimator, a central clock estimator, a predictive filter, an error reduction filter, and a Kalman filter.

The era can be set by one or more of the following: start time, end time, duration, or interval, or discrete moment when the reference receiver 51 takes a picture of the incoming radio frequency or microwave ranging signal and generates a carrier pseudorange / phase measurement. The current era means the most recent moment when the latest measurement is generated (for example, GPS measurement).

The clock difference difference module 28 provides program instructions or is capable of generating or determining clock error differences between pairs of computed satellite clock error data and broadcast clock data for each satellite in one or more orbital constellations. In one embodiment, for each satellite received by the reference receiver 51, the calculated satellite clock error is determined or estimated based on carrier phase measurements, pseudo-range code measurements, corresponding known fixed locations of the reference stations (10, 12, and 14) and satellite clock broadcast error. The clock difference difference module 28 may calculate a first set of calculated satellite clock error data regarding the GPS orbital constellation and a second set of computed satellite clock error data for the GLONASS orbital constellation or both.

In general, the absolute clocks of each satellite and positioning receiver are unobservable in every Global Navigation Satellite System (GNSS) (e.g. GPS and GLONASS) for determining the orbit and clock. At least one additional restriction, such as pseudo-code measurement or carrier phase measurement for each Global Navigation Satellite System (GNSS) system, is required to accurately determine satellite clock error and receiver clock error.

In one embodiment, the broadcast satellite clock error data may represent a clock offset, a clock deviation, or differential clock data with respect to a system clock of a corresponding orbital constellation (e.g., GPS system clock or GLONASS system clock). The clock difference module 28 or the data processing system 16 determines the difference of the clock errors or the error data between the calculated satellite clock error data and the broadcast clock data for each satellite in each satellite-based orbital constellation or is otherwise limited to specific subsets of satellites in each orbital constellation. Clock error differences or error data can be stored in one or more arrays or matrices in the data storage device 22, where each array corresponds to a particular orbital grouping. Although each array or matrix can cover all satellites in an orbital constellation, the matrix can be limited to a subset of each orbital constellation to reduce data processing time or computation time (for example, data processor 18), the need to determine and collect the calculated data of the error of satellite clocks or differences of clock errors in the central electronic data processing system 16 to achieve real-time reactivity in transmitting correction data (e.g., error corrections and h) the end user of mobile positioning receiver 42. To this end, some base satellites, such as the AMC-1 satellite or other satellites that have a historical accuracy of satellite clock data within 10 nanoseconds of accuracy with respect to the system time of the orbital constellation (for example, GPS system time), can be included in the subset of satellites in each orbital constellation for which differences or error data are calculated.

The reference satellite selection module 30 provides program instructions or is capable of selecting (for example, on a dynamic phased basis) one particular satellite for each orbital constellation as a reference clock satellite for each orbital constellation, where the reference clock satellite has a median value of the previously generated differences for each orbital constellation of satellites (for example, GPS and GLONASS) for a specific corresponding era. For example, the median value can be used instead of the median value to eliminate any erroneous effect or inconsistent effect of very different satellite clock data on the resulting error or difference data. If an average value were used, the resulting error data could be incorrectly biased by very different satellite clock data obtained from a malfunctioning satellite clock.

The clock correction module 32 provides program instructions or is capable of calculating or determining correction (for example, clock correction data 44 or satellite clock correction data) regarding broadcast satellite clock error data by adding or adjusting the broadcast satellite clock data for each satellite clock individually . For example, the clock correction module 32 is adapted to determine the clock error corrections by adding a function (for example, a mathematical function, a linear algebraic function, or matrix expression) of the clock difference or the error data associated with the selected reference satellite to each broadcast satellite clock error of other satellites in orbital constellation. In one embodiment, the clock correction module 32 comprises one or more of the following: a predictive filter, an error reduction filter, and a Kalman filter. In another embodiment, the clock correction module 32 and the parameter estimation module 26 may access, use, share, or implement the main predictive filter 27. The main predictive filter 27 includes a predictive filter, an error reduction filter, or a Kalman filter.

The communication module 34 provides program instructions or is capable of supporting the distribution of the calculated clock correction data 44 to user receivers (for example, via the satellite communication system illustrated in FIG. 1 or via a wireless communication system).

In one embodiment, one or more instances of an accurate satellite clock (eg, atomic clock) on each satellite in orbit is used as a broadcast satellite clock, as a potential main satellite clock, or as a source of satellite clock data. One or more instances of the satellite clock can be selected as the clock data source for correction data or position decisions of the mobile positioning receiver 42. For example, you can select a GPS satellite clock, a GLONASS satellite clock, or a hybrid of a GPS satellite clock and a GLONASS satellite clock as a clock data source. In the first example, the satellite clock data used in the watch correction data 44 contains the median value of the GPS satellite clock for the entire GPS orbital constellation or a substantial part (e.g., the predominant or statistically significant sample size) of the orbital constellation that serves a large area. In the second example, the satellite clock data used in the watch correction data 44 contains the median value of the GLONASS satellite clock for the entire GLONASS orbital constellation or a substantial part (for example, the predominant or statistically significant sample size) of the orbital constellation that serves a large area. In the third example, the satellite clock data used in the watch correction data contains the median value of the GPS satellite clock for the entire GPS orbital constellation and the median value of the GLONASS satellite clock for the entire GLONASS orbital constellation.

In accordance with one embodiment, a system and method for adaptive broadcast master clocks is well suited to eliminate the external input of an accurate clock frequency (e.g., an atomic clock of a receiver or an atomic reference oscillator at a reference receiver 51) and to reduce the complexity of daily operations and the development costs of a global or large-scale differential correction systems. The term “main clock” as used herein refers to a satellite clock of a reference clock for the GPS orbital constellation or GLONASS orbital constellation, which have a median value of the clock error differences for any era, so that the main clock can vary from era to era. Since, according to the present method and system, there is a very large number of satellites as a source of possible clock data, the reliability of these clocks can be further improved. Another advantage of the system and method is to facilitate correction of clocks or clock correction data 44 that have zero average values (or, for example, average values close to zero) and a correction drift rate that can be limited in accordance with predetermined or predetermined restrictions .

The system 111 shown in FIG. 2 is similar to the system 11 shown in FIG. 1, except that in the system 111 shown in FIG. 2, the satellite satellite ground device 38 and the satellite satellite remote device 40 are replaced by the wireless base station 138. The wireless base station 138 may represent, for example, part of a wireless communication network. Additionally, the mobile positioning receiver 42 is coupled to a correction transmission device 141 that includes a transceiver or a wireless communication device (e.g., a cellular, Global System for Mobile Communications (GSM) device, a code division multiple access (CDMA) device, or other wireless communication device) for communicating with the wireless base station 138. Similar reference numerals in FIG. 1 and FIG. 2 indicate similar elements.

According to FIG. 2, clock correction data 44 (e.g., clock error correction) is transmitted and made available to one or more mobile location receivers 42 associated with respective correction transmission devices 141 in the coverage area of the wireless base station 138 or the network of wireless base stations 138.

FIG. 3 illustrates an example of a mobile location receiver 42 that can be used according to the embodiment of FIG. 1 or FIG. 2. The mobile positioning receiver 42 comprises a high-frequency receiver stage 302 connected to an input of the analog-to-digital converter 306. The output (for example, a low-frequency digital signal) of the analog-to-digital converter 306 is connected to an electronic receiver data processing system 308.

The electronic receiver data processing system 308 includes a receiver data processor 310, a receiver data storage device 312, a receiver data bus 324, a data port 322, a decoder 320, and a phase measurement device 304. A receiver data processor 310, a receiver data storage device 312, a data port 322, a phase measuring device 304, and a decoder 320 are connected to the receiver data bus 324 to support communication between the aforementioned components of the electronic receiver data processing system 308.

The receiver data processor 310 may comprise a microprocessor, a controller, a matrix of programmable logic devices, a specialized integrated circuit, an arithmetic logic device, a logic device, an electronic data processing device, or other device for executing software, logical, arithmetic, or program instructions.

The receiver data storage device 312 comprises electronic memory, optical storage device, magnetic storage device, or other storage device. The receiver data storage device 312 includes a real-time kinematic machine 314, a predictive filter 316 (e.g., a Kalman filter), and a position estimator 318.

The location receiver 42 is connected to a correction transmission device (41 or 141). The correction transmission device (41 or 141) may be integrated into the location receiver 42 or may communicate with the location receiver via the data port 322. The correction transmission device (41 or 141) receives correction data (for example, clock error correction data (i.e., 44) and / or carrier phase correction data) from the central electronic data processing system 16 via one or more intermediate wireless or satellite devices communication (for example, 38, 40 in Fig. 1 or 138 in Fig. 2).

The high frequency receiver stage 302 may comprise any suitable circuit for receiving satellite signals transmitted by one or more satellites (e.g., navigation satellites). The high-frequency cascade 302 of the receiver may be capable of receiving, for example, signals from GPS and GLONASS satellites. The high frequency receiver stage 302 may comprise a spread spectrum system receiver or a code division multiple access (CDMA) system receiver that is capable of receiving multiple carriers transmitted by one or more satellites in an orbiting satellite constellation. For example, the high-frequency cascade 302 of the receiver may include a preamplifier or amplifier for amplifying satellite signals, a mixer and a reference generator, where the input of the amplifier is connected to the antenna, the output of the amplifier is connected to one input of the mixer, the reference generator is connected to another input of the mixer, and the output of the mixer is connected to system 308 processing receiver data.

In one embodiment, the analog-to-digital converter 306 provides an interface between a high frequency receiver stage 302 and an electronic receiver data processing system 308. An analog-to-digital converter 306 converts analog phase measurements to digital carrier phase measurements, which can be processed or manipulated by an electronic receiver data processing system 308.

The decoder 320 determines the measurements of the pseudo-range code and transmits the measurements of the pseudo-range code to the receiver electronic processing system 308. In one embodiment, decoder 320 comprises a demodulator or other device for demodulating a pseudo-random noise code (eg, coarse tracking code (C / A) or other more accurate civil or military coding) that modulates one or more carriers. For example, decoder 320 may comprise a group of correlators 351 (for example, one correlator per GPS channel and one correlator per GLONASS channel), where each correlator 351 is connected to a pseudo-random noise code generator 390 to provide demodulated in-phase (I) and quadrature (Q) signal component (e.g., amplitude and phase or vectors). For GPS, the carrier signal L1 is modulated by the coarse tracking code (C / A) and the encrypted exact code P (Y), while the signal L2 is modulated by the encrypted code P (Y). In one embodiment, the decoder may include a code generator connected to the input of the delay module, where the output of the delay module is connected to a correlator for measuring the correlation between the reference pseudo-random noise code, which can be delayed by known increments by the delay module, and the pseudo-random noise code received from the high-frequency stage 302 receivers. Decoder 320 may also facilitate decoding of navigation information that modulates a carrier signal, such as ephemeris data.

The phase measuring device 304 comprises any device, integrated circuit, electronic module or data processor for measuring the phase of the carrier signal. In one configuration, the phase measuring device 304 comprises a signal generator, a phase delay module connected to the first correlator and the second correlator. The phase measuring device measures or evaluates the observed phase of one or more carrier signals provided by the high frequency receiver stage 302. The measured phase can be expressed as an integer number of wavelengths of the carrier signal, a fractional number of wavelengths of the carrier signal and / or degrees of the carrier signal.

The phase measuring device 304 may determine one or more of the following: (1) a first measured phase component expressed as a fractional number of wavelengths of a first carrier signal, a second carrier signal or both, and (2) a second measured phase component expressed as an integer number of wavelengths of a first a carrier signal, a second carrier signal, or both. The last, second measured phase component can be determined using a counter (for example, a zero-crossing counter), which counts the transitions of a received, reconstructed, or processed carrier signal that intersects with the X axis at the origin of the value (for example, 0 voltage) in the time domain, where X represents time and the Y axis represents the magnitude of the carrier signal. However, the phase measuring device 304 relies on additional processing in the receiver data processing system 308 to determine or resolve an uncertainty expressed as an integer number of periods that can lead to an error or deviation of the second measured phase component by an integer number of wavelengths (for example, to estimate distance or range between the respective satellite and location receiver). The phase measuring device 304 determines and transmits the carrier phase measurement data to the receiver electronic processing system 308.

The real-time kinematic machine 314, the predictive filter 316, and the position estimator 318 can communicate with each other. The real-time kinematic machine 314, the predictive filter 316, and the position estimation module 318 can communicate with each other over logical data channels, physical data channels, or both types of channels. Logical data channel means a virtual data channel or data transfer between program modules or, for example, between one or more programs implemented by software. Physical data channel means a communication line or one or more receiver data buses 324 that support, for example, the transmission of data, logic level signals, electrical signals or electromagnetic signals.

In one embodiment, the real-time kinematic engine 314 comprises a search engine or other program instructions for searching or determining sets of integer uncertainty solutions for the phase of one or more carrier signals received from multiple satellites. The kinematic machine 314 may search for carrier phase data provided, for example, by a phase measuring device 304. Sets of integer uncertainty solutions relate to phase uncertainties, expressed as an integer number of periods, in the received carrier phase of the received carrier signals (e.g., L1 signal at a frequency of 1.57542 GHz, L2 signal at a frequency of 1.22760 GHz for GPS or similar signals) transmitted, for example, by one or more companions. Kinematic engine 314 or its search engine may use least squares or Kalman filtering techniques to narrow down the search space or achieve one or more sets of uncertainty solutions for phase uncertainties expressed as an integer number of periods carrying signals transmitted from satellites.

In one configuration, a predictive filter 316 (e.g., a Kalman filter) facilitates search engine search to more efficiently, quickly, or accurately achieve sets of uncertainty solutions for phase uncertainties expressed as an integer number of periods carrying signals transmitted from satellites. In an alternative embodiment, alternative non-search methods (e.g., processing wideband combinations of carrier phase and data) can be used to resolve sets of solutions of integer carrier phase uncertainty.

The evaluation module 318 includes a receiver data processor 310 or other data processing device for evaluating a position, speed, position, or any of the above attributes of an object or vehicle associated with a location receiver 42. The evaluation module 318 is connected to or communicates with the real-time kinematic machine 314 and the receiver data processor 310. Having determined the set of integer uncertainty solutions, the position estimation module 318 or the positioning receiver 42 may use carrier phase measurement data to provide an accurate estimate of the distance or distance between each satellite and the positioning receiver based on a known propagation speed (i.e., the speed of light). In turn, the distances between three or more satellites and the positioning receiver can be used to estimate the position, speed, or position of the receiver 42.

The predictive filter 316 comprises an error reduction filter, a Kalman filter or a variation thereof for reducing or decreasing errors, for example, measurement errors. The Kalman filter may include a predictive filtering device or circuit that uses signal summation, delay, and feedback to process the data and compensate for noise and uncertainty effects in the measured data or in something else. Reinstallation or reinitialization may mean the same as reinitialization of the states of the error reduction filter or Kalman filter.

The position estimation module 318 comprises an electronic module, a software module, or both modules for estimating the position of an object or vehicle associated with a location receiver. The position estimation module may use one or more of the following data sources to determine the estimated position or position of the antenna of the positioning receiver or an associated object or vehicle: a decoded pseudo-random noise code, carrier phase measurement data, an encrypted exact code (e.g., P ( Y)), a rough tracking code, navigation information and phase uncertainty data, expressed as an integer number of periods, and phase data of the carrier reference station, where phase data of the carrier reference station can be integrated into phase uncertainty data expressed as an integer number of periods.

The predictive filter 316 may include an error reduction filter that receives input from the real-time kinematic machine 314, where the input contains uncertainty decision data (eg, a set of integer uncertainty solutions) for the respective carrier phase measurement data. In one embodiment, the reference receiver 51 shown in FIG. 1 and FIG. 2 may comprise substantially the same elements as the mobile location receiver 42 shown in FIG. 3, except that the reference receiver 51 is not connected to the correction transmission device (41 or 141).

In FIG. 4 shows a first example flowchart of a method for determining clock correction data 44. The method shown in FIG. 4 begins with step S400.

In step S400, the data collection module 24 or the central electronic data processing system 16 collects pseudo-range code measurements, carrier phase measurements and broadcast clock errors received by the network 15 of reference station receivers (e.g., 10, 12 and 14). For example, the reference station receiver network 15 comprises stationary reference receivers 51 located at respective known locations or with known geographical coordinates, where the reference receivers 51 receive signals at multiple frequencies (e.g., multiple carrier frequencies) transmitted by one or more orbital constellations of navigation satellites. One or more orbital constellations may comprise a GPS orbital constellation, a GLONASS orbital constellation, or another orbital constellation of navigation satellites. For the orbital constellation of GPS satellites, multiple frequencies may comprise, for example, a carrier frequency L1 and a carrier frequency L2. For the orbital constellation of GLONASS satellites, multiple carrier frequencies are assigned to different satellites.

At the reference receiver 51, a phase measuring device or receiver data processing system 53 measures the carrier phases of the respective carrier signals received by the reference receiver 51. The carrier phase measurements may include, for example, GPS carrier phase measurement data and GLONASS carrier phase measurement data. The decoder in the reference receiver 51 may decode the transmitted ephemeris data, broadcast errors of the satellite clock and other navigation data that are transmitted to or which modulates at least one of the carrier signals of one or more satellite signals. In one configuration, carrier phase measurements, pseudo-range code measurements, and navigation message data are transmitted from the receiver network 15 to the central data processing system 16 via one or more communication lines 13.

Each satellite typically sends ephemeris data and satellite clock error data (for example, differential clock data for GPS system time or GLONASS system time for a particular satellite). Clock broadcast data is a set of matched second-order polynomial coefficients used by the receiver to correct measurements of the pseudorange and carrier phase of the positioning receiver (for example, reference receiver 51). Each navigation satellite transmits ephemeris data of its own orbit and satellite clock readings. The accuracy of broadcast errors of a satellite clock is usually, for example, of the order of 2-3 meters relative to GPS time.

In step S402, at each time interval (eg, an epoch), the parameter estimator 26 or the central electronic data processing system 16 estimates the calculated satellite clock error data for each satellite based on one or more of the following collected data: measurements of the pseudo-range network code of 15 receivers for each satellite, phase measurements of the carrier network of 15 receivers for each satellite, the corresponding known locations of the stationary reference receivers 51 in the network of 15 receivers and broadcast satellite clock errors.

Step S402 may be carried out in accordance with various methods that can be applied alternately or collectively. According to the first method, at each time interval (for example, an epoch), the parameter estimation module 26 or the central electronic data processing system 16 estimates the satellite clock error data for each satellite that is active or correctly functioning in one or more orbital constellations (for example, GPS, GLONASS or both), based on measurements of the pseudo-range code, measurements of the carrier phase, the corresponding known locations of the stationary receivers and broadcast errors of satellite parts s navigation message or data (e.g., which includes the broadcast satellite clock error).

According to the second method, if a satellite provides distorted or unreliable satellite signals or distorted or unreliable data for a certain period of time, the parameter estimator 26 or central data processing system 16 may suspend processing of satellite clock error data for a defective or suspicious satellite for a period time until the signal received from the satellite, will not have sufficient signal quality or level of reliability of the received data.

According to the third method, the parameter estimation module 26 or the central electronic data processing system 16 uses a single difference procedure or another procedure to determine the calculated satellite clock error data for each corresponding satellite in one or more orbital constellations (for example, GPS or GLONASS orbital constellations). For example, in one embodiment, every possible combination or permutation of a pair of different receivers and one satellite that is available (for example, received with adequate signal strength or signal quality on any pair of reference receivers 51) is used to estimate the error or offset of the clock (for example, the calculated error satellite clock) for each satellite in a particular orbital constellation in accordance with the repeated use of the single difference between the measurements of the phase of the carrier of the reference receivers 51. The calculated satellite clock error data can be expressed as the differential time or offset relative to the GPS system time or GLONASS system time.

According to the fourth method, the clock difference difference module 28 or the central electronic data processing system 16 uses a double difference procedure or another procedure to determine the calculated satellite clock error data. For example, a double difference procedure means the difference between the measurements of the carrier phase from two reference receivers 51 (for example, at known fixed locations or geographical coordinates), which essentially simultaneously receive carrier signals from the same pair of two satellites to determine the calculated error data satellite clock with reduced error or clock offset. For example, in one embodiment, every possible combination or permutation of a pair of different receivers and a pair of satellites that is available (for example, received with adequate signal strength or signal quality on any pair of reference receivers 51) is used to estimate the error or clock offset for each satellite in specific orbital grouping in accordance with the repeated use of the double difference between the measurements of the phase of the carrier of the reference receivers 51. In practice, the double difference can be determined by taking the second difference of the two definitions of a single difference. The calculated satellite clock error data can be expressed as the differential time or the offset relative to the GPS system time or GLONASS system time.

In step S406, the clock difference module 28 or the central electronic data processing system 16 generates or determines the clock error differences (for example, differential data or differential clock error data) between the respective pairs of calculated satellite clock error data and the corresponding broadcast clock data for each satellite. For example, the calculated satellite clock error data is satellite clock data that is consistent with a known fixed location of the reference receiver 51 at a particular reference station (e.g., 10, 12 or 14), and carrier phase measurements of a specific reference station (e.g., 10, 12 or 14) for a specific satellite.

The broadcast data of the clock is provided by or inferred from the exact clock (for example, a rubidium, cesium or atomic clock) installed on each satellite. In one embodiment, the broadcast clock data comprises differential clock data or clock offset data relative to the system clock of the orbital grouping. In another embodiment, the broadcast clock data represents the transmitted satellite clock data (and corresponding ephemeris data).

Step S406 may be performed in accordance with various methods that can be applied individually or in combination.

According to the first method, the clock difference module 28, the central electronic data processing system 16, or the main predictive filter 27 (for example, the Kalman filter) in the data processing system 16 uses one or more of the following to find the difference of the clock errors on a satellite basis for one or more orbital constellations and for each subsequent era: (1) the corresponding calculated satellite clock error data for one or more satellites in a common orbital constellation, (2) the corresponding broadcast satellite clock error data for one or more satellites in a common orbital constellation; and (3) corresponding broadcast satellite clock error data for a common orbital constellation, adjusted or adjusted based on accompanying ephemeris data for a particular satellite. A common orbital constellation means the same orbital constellation of satellites, which may contain, for example, the GPS orbital constellation or the GLONASS orbital constellation.

According to the second method, the clock difference module 28 or the data processing system 16 determines the differences or error data between the calculated satellite clock error data and the broadcast clock error data for each satellite in each satellite constellation, or, otherwise, is limited to specific subsets of satellites in to each orbital constellation. Differences or error data can be stored in one or more arrays or matrices in the data storage device 22, where each array corresponds to a specific orbital grouping.

In step S408, the reference satellite selection module 30 or the electronic data processing system 16 selects one of the satellites in each orbital constellation as the reference clock satellite for this orbital constellation, where the reference clock satellite has a median value of the clock error differences (for example, from step S406) for this orbital constellation. In the first example, for step S408, the reference satellite selection module 30 or the electronic data processing system 16 selects one of the satellites in the GPS orbital constellation as the reference clock satellite for the GPS orbital constellation, where the reference clock satellite has a median value of the differential data or the clock error data for GPS orbital constellation. In the second example, for performing step S408, the reference satellite selection module 30 or the electronic data processing system 16 selects one of the satellites in the GLONASS orbital group as the reference clock satellite for the GLONASS orbital group, where the reference clock satellite has the average value of the differential data or the clock error data for GLONASS orbital grouping.

In step S410, the clock correction module 32 or the electronic data processing system 16 determines or calculates the correction or correction data regarding the clock broadcast data by adjusting the broadcast clock error data of each satellite in one or more orbital constellations. For example, the clock correction module 32 or the data processing system 16 adjusts the broadcast clock error data of each satellite by summing the satellite clock error function of the reference clock with the broadcast clock error for each satellite in one or more orbital groups, where the correction value for each era or other time interval (e.g., several neighboring eras) is limited based on the limit of the control parameter.

Step S410 may be performed in accordance with various procedures that may be applied individually or in combination.

According to the first procedure, the control parameter limit is proportional to the satellite clock error of the reference clock. According to the second procedure, the control parameter limit is less than or approximately equal to the satellite clock error of the reference clock. According to the third procedure, the control parameter limit contains a fixed parameter, expressed in units of distance, after the main predictive filter 27 (for example, Kalman filter) converges to a solution for correcting the broadcast error of the satellite clock.

According to the fourth procedure, for each corresponding navigation satellite in the first orbital group in one or more orbital groups, the calculated correction is limited in each era to the first satellite clock error of the reference clock of the first orbital group and for each corresponding navigation satellite in the second orbital group in one or more orbital groups the calculated correction is limited in each era by the second error of the satellite clock of the WTO reference clock swarm of orbital grouping, where the first error of the clock does not depend on the second error of the clock. For example, the first orbital grouping may contain the orbital grouping of the Global Positioning System and the second orbital grouping may contain the GLONASS orbital grouping.

According to the fifth procedure, after the convergence of the solution for correcting the broadcast error of the clock, the calculated correction is limited in each era so that it does not exceed the threshold value. According to the sixth procedure, the threshold value is approximately one millimeter in distance units, or approximately .00333 nanoseconds in equivalent time units, where the conversion coefficient between distance units and time units is equal to the speed of light (for example, 3x10 ⁸ meters per second). According to the seventh procedure, the satellite clock error of the reference clock is applied as an additional restriction to the main predictive filter 27 (for example, Kalman filter).

According to the eighth procedure, the clock correction module 32 or the electronic data processing system 16 determines or calculates the correction data regarding the broadcast clock error data by limiting the clock error correction regarding the broadcast clock error to the maximum amount of clock correction for each era or other time interval (e.g., multiple neighboring eras), which is less than or equal to one or more of the following: (a) the corresponding maximum threshold (for example, approximately equal to or less than 1 millimeter for each era or other time interval, or approximately equal to or less than .00333 nanoseconds), (b) standard error (RMS) in the range estimate, or (c) the corresponding maximum threshold, expressed in units of distance or equivalent units of time, where the speed of light is the conversion factor. For example, the change per unit time in the clock error correction data can be limited based on the navigation message data (e.g., ephemeris data and the broadcast clock error data), as a result of which the clock error correction data or the temporary correction data of the positioning receiver 42 are changed less. than the maximum displacement per unit time, which otherwise would lead to undesirable violations of continuity, discrepancies or inaccuracies, respectively The associated position estimates determined by the end user’s location receiver 42.

According to the ninth procedure, the clock correction module 32 or the electronic data processing system 16 at regular or periodic intervals (e.g., epochs) determines the following clock error correction data with respect to broadcast clock error data by dynamically adjusting in real time the change in the clock error data per unit time that is less than or equal to the corresponding maximum threshold (for example, less than about 1 millimeter for each era or other time interval or less approximately .00333 nanoseconds for each era or other time interval).

According to the tenth procedure, step S410 can be performed by setting the limit of the control parameter to change per unit time in the clock error correction data based on the average value of the difference between the pairs of calculated satellite clock error data and the broadcast clock error data (or ephemeris clock data) in a particular orbital group navigation satellites. For example, step S410 may be performed by limiting the clock error corrections (or the maximum correction shift) determined by the central data processing system 16 or the clock correction module 32 for transmission to the location receiver 42 as follows:

In Equation 1, the median value of the GPS clock difference between the calculated satellite clock error data from the parameter estimator 26 and the ephemeris clock data or the broadcast satellite clock error data received from the network of 15 receivers can be determined as follows:

$$dCl{k}_{GPS}=Median(cloc{k}^i(hub)-cloc{k}^i(eph)),i=\mathrm{one}:32\text{for GPS (1)}$$

- срединное значение разности хода часов GPS для орбитальной группировки GPS, $$cloc{k}^i(hub)$$

- вычисленные данные погрешности часов для i-го спутника, $$cloc{k}^i(eph)$$

- эфемеридные данные часов или широковещательные данные погрешности часов для i-го спутника и i - идентификатор спутника для каждого из 32 спутников GPS.Where $$dCl{k}_{GPS}$$

- the median value of the difference in the progress of the GPS clock for the GPS orbital constellation, $$cloc{k}^i(hub)$$

- calculated clock error data for the i-th satellite, $$cloc{k}^i(eph)$$

- ephemeris clock data or broadcast clock error data for the i-th satellite and i - satellite identifier for each of the 32 GPS satellites.

In one embodiment, the computed satellite clock error data and the ephemeris clock data or broadcast satellite clock error data are converted to equivalent units and to the same or essentially the same era before calculating the aforementioned median GPS clock difference for orbital grouping GPS As described further in Equations 3 and 4, the above definition of the average GPS clock difference can be used by the data processing system 16 or its predictive filter (e.g., Kalman filter) to determine the limits for the clock error correction data (e.g., clock error corrections), or the maximum change in the correction error of the clock per unit time, or its application in the mobile receiver 42 positioning.

In equation 2, the average value of the GLONASS clock travel difference between the calculated satellite clock error data from the parameter estimating module 26 and the ephemeris clock data or broadcast satellite clock error data received from the network of 15 receivers can be determined as follows:

$$dCl{k}_{GLONASS}=Median(cloc{k}^j(hub)-cloc{k}^j(eph)),\text{j = 1: 24 for GLONASS (2)}$$

- срединное значение разности хода часов ГЛОНАСС для орбитальной группировки ГЛОНАСС, $$cloc{k}^j(hub)$$

- вычисленные данные погрешности спутниковых часов для j-го спутника, $$cloc{k}^j(eph)$$

- эфемеридные данные часов или широковещательные данные погрешности спутниковых часов для j-го спутника и j - идентификатор спутника для каждого из 24 спутников ГЛОНАСС.Where $$dCl{k}_{GLONASS}$$

- the median value of the difference in the movement of the GLONASS hours for the GLONASS orbital group, $$cloc{k}^j(hub)$$

- calculated satellite clock error data for the j-th satellite, $$cloc{k}^j(eph)$$

- ephemeris clock data or broadcast satellite clock error data for the j-th satellite and j - satellite identifier for each of the 24 GLONASS satellites.

In one embodiment, the computed satellite clock error data and the ephemeris clock data or broadcast satellite clock error data are converted to equivalent units and to the same or essentially the same era before calculating the aforementioned aforementioned average value of the GLONASS clock difference. As described below in equations 3 and 4, the above definition of the average value of the GLONASS clock difference can be used by the data processing system 16 or its main predictive filter 27 (e.g., Kalman filter) to determine the limits on the clock correction data (e.g., clock error corrections), or a maximum change in the watch correction data per unit of time, or its application in the mobile location receiver 42.

In one embodiment, the data processing system 16, clock correction module 32, or predictive filter (e.g., Kalman filter) maintains or determines that clock error corrections are smooth or continuous (e.g., as far as possible or practical) to avoid any possible disruption to the continuity correction or a sharp change in the correction of the clock error; therefore, the dependent position of the speed estimates based on the clock error corrections on the mobile location receiver 42. The maximum change in the clock readings per unit of time (for example, for each era or other time interval) of updating the constraint (for example, updating to correction data or updating the status of the predictive filter 27) in the parameter estimating module 26, the correction module 32, or the predictive filter 27 (for example, Kalman filter) in the central data processing system 16 should be limited according to equation 3:

where dX - update status to evaluate the correction hours; H is a plan matrix containing sensitivity coefficients; P is the dispersion-covariance matrix; dClk is the satellite clock error of the reference clock, Threshold is the threshold of the maximum correction correction in movement in distance units (for example, 1 mm) or in equivalent time units; R is the variance of the applied correction data.

Based on equation 3, the variance R or adaptive dispersion of the broadcast signal of the main clock from the GPS and GLONASS satellite can be calculated in the reverse order from the main predictive filter 27 (for example, Kalman filter) or parameter estimation module 26, then adaptive restriction (for example, adaptive correction data for adaptive main clock or satellite reference clock for GPS orbital constellation or GLONASS orbital constellation) can be applied to the main predictive filter 27 or estimation module 26 parameters.

The threshold level T _{R of} variance can be set in accordance with the following equation 4:

where T _R is the threshold level of variance for R and where other parameters are defined above.

In one example, if the calculated variance R exceeds the variance threshold level T _R , the clock correction unit 32 or the main predictive filter 27 uses the calculated variance R to limit or update the correction status or the clock correction data (e.g., clock error corrections). In another example, if the calculated variance R is less than the variance threshold level T _R , the clock correction unit 32 or the prediction filter 27 uses the variance threshold level T _R to limit or update correction data (e.g., clock error corrections).

In an alternative embodiment, the dispersion threshold level T _R may comprise a predetermined dispersion level or a constant parameter set by the user based on empirical studies of the performance of the main clock or based on the historical accuracy of the position estimates of the mobile positioning receiver 42. For example, the threshold level of dispersion may be pre-set or pre-set equal to .01 m ² .

The median value (for example, the median value of GPS or the median value of GLONASS) of the difference between the clock errors between the parameter estimating module 26 (for example, the orbit / clock estimator of the concentrator) and the broadcast clock error (for example, the ephemeris clock) received by the network of 15 receivers increases the reliability, since some satellites may have abnormal, very different or deviating satellite clocks, at least sometimes. If the restriction introduced in the main predictive filter 27 (for example, Kalman filter) or parameter estimator 26 is too strict or strong, this can lead to a significant jump in the correction data in the resulting correction data. If the restriction introduced in the main predictive filter 27 (e.g., Kalman filter) or the parameter estimator 26 is too weak, this can lead to a slow drift in the resulting correction data and a large dispersion for the clock estimate due to non-observability between the satellite clock and the receiver clock ( e.g. reference receiver 51). To solve the above technical problems, in accordance with one embodiment, adaptive broadcast main clocks are proposed in which the change in clock correction is limited in some predetermined or predetermined ranges.

In step S412, the communication module 34, the communication interface 36, or the data processing system 16 distributes or transmits the calculated clock correction data 44 (e.g., clock error correction) to the mobile positioning receivers 42 (e.g., user positioning receivers) via satellite, wireless or other communication system. In one example consistent with the system shown in FIG. 1, a data processing system 16 distributes or transmits clock correction data 44 through a satellite-based ground-based communications device 38 that provides an uplink satellite channel to a remote satellite communications device 40 on a satellite orbiting around the earth. The remote satellite communications device 40 provides a downlink channel to the correction transmission device 41 for receiving correction data for input to the mobile positioning receiver 42.

In another example consistent with the system shown in FIG. 2, the data processing system 16 transmits the clock correction data 44 via the wireless base station 138 to the correction transmission device 141 or the transceiver associated with the mobile location receiver 42.

In accordance with the system and method, the estimated parameters of all satellite clocks and clocks of the positioning receivers can be set with respect to the constraints referred to as the master clock data or satellite clock of the reference clock for a particular orbital constellation. For a global real-time differential correction system, or a large-scale correction system, or any embodiment of a system and method disclosed herein, an electronic data processing system is well suited for generating smooth clock correction data (for example, without transient jumps) and a strictly limited range of clock correction data for preserving the bandwidth of communication lines between sections of the differential correction system and for predicting real-time clock corrections with a minimum of rzhkoy processing.

In FIG. 5 shows a second example of a flowchart of a method for determining clock correction data 44. Similar reference numerals in FIG. 4 and FIG. 5 indicate similar procedures or methods. The method shown in FIG. 5 begins with step S401.

In step S401, the data acquisition unit 24 or the central electronic data processing system 16 collects pseudo-range code measurements, carrier phase measurements and navigation message data (e.g., ephemeris data and clock data) received by the network of 15 reference station receivers (e.g., 10, 12 and 14 ) For example, the reference station receiver network 15 comprises stationary reference receivers 51 located at respective known locations or with known geographical coordinates, where the reference receivers 51 receive signals at multiple frequencies (e.g., multiple carrier frequencies) transmitted by one or more orbital constellations of navigation satellites. One or more orbital constellations may comprise a GPS orbital constellation, a GLONASS orbital constellation, or another orbital constellation of navigation satellites. For the orbital constellation of GPS satellites, multiple frequencies may comprise, for example, a carrier frequency L1 and a carrier frequency L2. For the orbital constellation of GLONASS satellites, multiple carrier frequencies are assigned to different satellites.

At the reference receiver 51, a phase measuring device or receiver data processing system 53 measures the carrier phases of the respective carrier signals received by the reference receiver 51. The carrier phase measurements may include, for example, GPS carrier phase measurement data and GLONASS carrier phase measurement data. The decoder in the reference receiver 51 may decode the transmitted ephemeris data, satellite clock data and other navigation data that are transmitted to or which modulate at least one of the carrier signals of one or more satellite signals. Carrier phase measurements, pseudo-range code measurements, and navigation message data are transmitted from the receiver network 15 to the central data processing system 16 via one or more communication lines 13.

Each satellite typically sends broadcast ephemeris data and broadcast satellite clock error data (for example, differential clock data for GPS system time or GLONASS system time for a particular satellite). Broadcast ephemeris data is a set of matched second-order polynomial coefficients used by the receiver to predict the behavior of the receiver clock for a positioning receiver (eg, reference receiver 51). Each navigation satellite transmits ephemeris data of its own orbit and satellite clock readings. The accuracy of the broadcast ephemeris clock is usually, for example, of the order of 2-3 meters relative to GPS time.

In step S403, at each time interval (eg, an era), the parameter estimator 26 or the central electronic data processing system 16 estimates the calculated satellite clock error data for each satellite based on one or more of the following collected data: measurements of the pseudo-range network code of 15 receivers for each satellite measurements of the phase of the carrier network of 15 receivers for each satellite, the corresponding known locations of the stationary reference receivers 51 in the network of 15 receivers and navigation data messages (for example, ephemeris data, and broadcast data error of satellite clock).

Step S403 may be carried out in accordance with various methods that can be applied alternately or collectively. According to the first method, at each time interval (for example, an epoch), the parameter estimation module 26 or the central electronic data processing system 16 estimates the satellite clock error data for each satellite that is active or correctly functioning in one or more orbital constellations (for example, GPS, GLONASS or both), based on measurements of the pseudo-range code, measurements of the carrier phase, the corresponding known locations of the stationary receivers and the data of the navigation message.

According to the second method, if a satellite provides distorted or unreliable satellite signals or distorted or unreliable data for a certain period of time, the parameter estimator 26 or central data processing system 16 may suspend processing of satellite clock error data for a defective or suspicious satellite for a period time until the signal received from the satellite, will not have sufficient signal quality or level of reliability of the received data.

According to the third method, the parameter estimation module 26 or the central electronic data processing system 16 uses a single difference procedure to determine the calculated satellite clock error data for each corresponding satellite in one or more orbital constellations (for example, GPS or GLONASS orbital constellations). For example, a single difference procedure means the difference between measurements of the carrier phase from two reference receivers 51 (for example, at known fixed locations or geographical coordinates), which essentially simultaneously receive carrier signals from the same satellites to determine the calculated satellite clock error data with reduced error or clock deviation. The calculated satellite clock error data can be expressed as the differential time or the offset relative to the GPS system time or GLONASS system time.

According to the fourth method, the clock difference difference module 28 or the central electronic data processing system 16 uses a double difference procedure to determine the calculated satellite clock error data. For example, a double difference procedure means the difference between the measurements of the carrier phase from two reference receivers (for example, at known fixed locations or geographical coordinates), which essentially simultaneously receive carrier signals from the same pair of two satellites to determine the calculated satellite error data hours with reduced error or clock offset. In practice, the double difference can be determined by taking the second difference of the two definitions of a single difference, where a single difference means the difference between the measurements of the carrier phase from two reference receivers 51 (for example, at known fixed locations or geographical coordinates), which essentially simultaneously receive carrier signals from the same satellites to determine the calculated satellite clock error data with reduced clock error or deviation. The calculated satellite clock error data can be expressed as the differential time or the offset relative to the GPS system time or GLONASS system time.

Other steps or procedures shown in FIG. 5, including steps S406, S408, S410, and S412, are identical or substantially similar to those described in the method of FIG. four.

In FIG. 6 is a flowchart of a method for determining a position estimate or a speed estimate at a receiver that receives clock error corrections. The method shown in FIG. 6 begins with step S600. The method shown in FIG. 6 may use the embodiment of the location receiver shown in FIG. 3, or another configuration of a positioning receiver that is capable of receiving and using clock error corrections to provide more accurate position estimates than would otherwise be possible.

At step S600, a decoder 320 or an electronic receiver data processing system 308 decodes the pseudo-range code measurements received by the positioning receiver 42 on the respective carrier signals transmitted to one or more navigation satellites.

In step S602, the phase measuring device 304 or the receiver electronic data processing system 308 determines the carrier phase measurements for the respective carrier signals.

In step S604, a decoder 320 or an electronic receiver data processing system 308 receives broadcast errors of a satellite clock on carrier signals from one or more navigation satellites.

At step S606, the correction transmission device (41 or 141) or the data port 322 of the electronic receiver data processing system 308 receives the correction for the broadcast clock error of each navigation satellite, which includes the satellite clock error of the reference clock added to the broadcast clock error for each navigation satellite in one or more orbital groupings, where the correction value for each era is limited based on the limit of the control parameter.

At step S608, the data processing system 308 or the position estimation module 318 determines the position estimate of the positioning receiver based on the decoded pseudo-range code measurements, the determined carrier phase measurements, the received satellite clock broadcast errors, and the received correction. For example, the data processing system 308 or position estimation module 318 may resolve phase uncertainties or integer phase uncertainties so that certain carrier phase measurements are at an estimated location consistent with the received clock error correction correction.

Step S608 may be carried out in accordance with various methods that can be used individually or in combination.

According to the first method, the data processing system 308 or the position estimation module 318 can determine the position estimate and the speed estimate of the positioning receiver based on the decoded measurements of the pseudo-range code, certain measurements of the carrier phase, the received broadcast errors of the satellite clock, and the received clock error corrections (e.g. basis).

According to the second method, the control parameter limit is proportional to the satellite clock error of the reference clock. According to the third method, the control parameter limit is less than or approximately equal to the satellite clock error of the reference clock. According to the fourth method, the change in the correction or correction of the clock for each era or other time interval (for example, multiple neighboring eras) is limited according to the following equation:

,

,

where dX - update status to evaluate the correction hours; H is the plan matrix with sensitivity coefficients; P is the dispersion-covariance matrix; R is the variance of the applied correction data; dClk is the satellite clock error of the reference clock, and Threshold is the maximum correction change allowed for each era, as disclosed in the claims.

According to the fifth method, if the calculated variance R of the applied correction data is greater than the value of T _R below, the calculated variance R is used to update the correction state.

.

.

According to the sixth method, if the calculated variance R is less than the value of T _R , T _{R is} used instead of R to update the correction state in accordance with the equations provided according to the fourth and fifth methods.

It follows from the described preferred embodiment that various modifications can be proposed without departing from the scope of the invention defined in the following claims.

Claims (25)

1. A method for determining satellite clock corrections, enabling at least one location receiver to provide at least one of a position estimate, a speed estimate, or a time estimate, the method comprising the steps of:
collecting pseudo-range code measurements, carrier phase measurements and broadcasting errors of satellite clocks from a network of stationary satellite signal receivers transmitted by one or more orbital constellations of navigation satellites,
in each era, the calculated satellite clock error for each navigation satellite is calculated based on measurements of the pseudo-range code, carrier phase measurements and broadcast errors of the satellite clock,
form the difference of the error of the clock between the corresponding pairs of the calculated error of the satellite clock and the broadcast error of the satellite clock for each navigation satellite,
for each orbital constellation, a satellite of the reference clock is selected from the navigation satellites in this orbital constellation, which has a median value of the difference of clock errors for this orbital constellation of satellites, and
the correction of the broadcast error of the clock of each navigation satellite is calculated by summing the error function of the satellite clock of the reference clock with the broadcast error of the clock for each navigation satellite in one or more orbital groups, where the correction value for each era or other time interval is limited based on the limit of the control parameter. 2. The method according to claim 1, in which the limit of the control parameter is proportional to the error of the satellite clock of the reference clock. 3. The method of claim 1, wherein the control parameter limit is less than or approximately equal to the satellite clock error of the reference clock. 4. The method according to claim 1, in which the limit of the control parameter contains a fixed parameter, expressed in units of distance or time, after the predictive filter converges to a solution for correcting the broadcast error of the satellite clock. 5. The method according to claim 1, in which, for each corresponding navigation satellite in the first orbital constellation in one or more orbital constellations, the calculated correction is limited in each era to the first satellite clock error of the reference clock of the first orbital constellation, and for each corresponding navigation satellite in the second orbital constellation in one or more orbital constellations, the calculated correction in each era is limited to the second error of the satellite clock of the reference clock w orbital grouping, and the first error of the clock does not depend on the second error of the clock. 6. The method according to claim 5, in which the first orbital grouping contains the orbital grouping of the Global Positioning System and the second orbital grouping contains the GLONASS orbital grouping. 7. The method according to claim 1, in which, after convergence of the solution for correcting the broadcast error of the clock, the calculated correction is limited in each era so that it does not exceed the threshold value. 8. The method according to claim 7, in which the threshold value is approximately one millimeter or an equivalent time threshold. 9. The method according to claim 1, in which the use of the satellite clock error of the reference clock as the limit of the control parameter is carried out as an additional restriction on the predictive filter. 10. The method according to claim 1, in which the change in the correction or correction of the clock for each era is limited according to the following equation:

,
where dX is the update of the state to estimate the clock correction, H is the plan matrix with sensitivity coefficients, P is the dispersion-covariance matrix, R is the variance of the applied correction data, dClk is the error of the satellite clock of the reference clock, and Threshold is the maximum change in the correction for each era or control parameter. 11. The method according to claim 1, in which if the calculated variance R of the correction data used by the correction data is greater than the threshold variance level T _R , then the calculated variance, R, is used to update the correction state according to the following equation:

,
where H is the plan matrix with sensitivity coefficients, P is the dispersion-covariance matrix, dClk is the satellite clock error of the reference clock, and Threshold is the maximum correction change for each era or the control parameter limit. 12. The method according to claim 1, in which if the calculated variance R is less than the threshold level T _{R of the} variance, T _{R is} used instead of R to update the correction state according to the following equation:

,
where H is the plan matrix with sensitivity coefficients, P is the dispersion-covariance matrix, dClk is the satellite clock error of the reference clock, and Threshold is the maximum correction change for each era or the control parameter limit. 13. A system for determining satellite clock corrections, enabling at least one location receiver to provide at least one of a position estimate, a speed estimate, or a time estimate, the system comprising
a data acquisition module for collecting measurements of a pseudo-range code, carrier phase measurements and broadcast clock errors from a network of stationary receivers of satellite signals transmitted by one or more orbital constellations of navigation satellites,
a parameter estimation module for calculating the calculated satellite clock error for each navigation satellite based on pseudo-range code measurements, carrier phase measurements and broadcast clock errors,
a clock movement difference module for generating clock error differences between respective pairs of calculated satellite clock error data and corresponding broadcast clock data for each navigation satellite,
a reference satellite selection module for selecting a reference clock satellite from navigation satellites, which has a median value of the clock error differences for this orbiting satellite constellation, and
a clock correction module for calculating a correction for a broadcast clock error by summing a satellite clock error function of a reference clock with a broadcast clock error for each navigation satellite in one or more orbital groupings, where the correction value for each era or other time interval is limited based on a control parameter limit. 14. The system of claim 13, wherein the control parameter limit is proportional to the satellite clock error of the reference clock. 15. The system of claim 13, wherein the control parameter limit is less than or approximately equal to the satellite clock error of the reference clock. 16. The system of claim 13, wherein the control parameter limit comprises a fixed parameter, expressed in units of distance or time units, after the predictive filter converges to a solution for correcting a broadcast error of a satellite clock. 17. The system according to item 13, in which, for each corresponding navigation satellite in the first orbital constellation in one or more orbital constellations, the calculated correction is limited in each era to the first satellite clock error of the reference clock of the first orbital constellation, and for each corresponding navigation satellite in the second orbital constellation in one or more orbital constellations, the calculated correction in each era is limited to the second error of the clock of the satellite of the reference clock the second orbital group, and the first error of the clock does not depend on the second error of the clock. 18. The system according to 17, in which the first orbital grouping contains the orbital grouping of the Global Positioning System and the second orbital grouping contains the GLONASS orbital grouping. 19. The system according to item 13, in which, after convergence of the solution for the correction of the broadcast clock error, the calculated correction is limited in each era so that it does not exceed the threshold value. 20. The system of claim 19, wherein the threshold value is approximately one millimeter or an equivalent time threshold. 21. The system of claim 13, wherein the correction module comprises a predictive filter adapted to receive the satellite clock error of the reference clock as an additional limitation. 22. The system according to item 13, in which the change in the correction or correction of the clock for each era is limited according to the following equation:

,
where dX is the update of the state to estimate the clock correction, H is the plan matrix with sensitivity coefficients, P is the dispersion-covariance matrix, R is the variance of the applied correction data, dClk is the error of the satellite clock of the reference clock, and Threshold is the maximum change in the correction for each era or control parameter. 23. The system of claim 13, wherein, in the main predictive filter of the clock correction module, if the calculated variance R of the correction data, the applied correction data is greater than the variance threshold level T _R , the calculated variance, R, is used to update the correction state according to the following equation :

where H is the plan matrix with sensitivity coefficients, P is the dispersion-covariance matrix, dClk is the satellite clock error of the reference clock, and Threshold is the maximum correction change for each era or the control parameter limit. 24. The system according to item 13, in which, in the main predictive filter of the clock correction module, if the calculated dispersion R is less than the threshold level T _{R of the} variance, T _{R is} used instead of R to update the correction state according to the following equation:

,
where H is the plan matrix with sensitivity coefficients, P is the dispersion-covariance matrix, dClk is the satellite clock error of the reference clock, and Threshold is the maximum correction change for each era or the control parameter limit. 25. The system of claim 13, wherein the correction module comprises a predictive filter, wherein after initializing the predictive filter, the correction data for the broadcast clock data, the calculated correction data are limited to a maximum value for each time interval that does not exceed the satellite clock error of the reference clock.

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