Time-scale propagation using global navigation satellite systems and its applications

Abstract

A method and apparatus are provided for propagating a time-stamped signal from at least one server site to at least one client site. The method includes: at each server site, running a server GNSS process configured to generate a server GNSS output raw data signal based on at least one or more first satellite signals; generating a precise orbit and clock signal embedded with the time-stamped signal based on all server GNSS output signals, and broadcasting the precise orbit and clock signal via a telecommunications network; at each client site, running a client GNSS process configured to run a client precise point positioning (PPP) process based on a client clock signal and generating a client GNSS output raw data signal based on one or more second satellite signals, the PPP process being configured to receive the client GNSS output raw data signal and the precise orbit and clock signal, and generate a difference signal between the client clock signal and the time-stamped signal.

Description

[0001] This application is a divisional application of the invention patent application filed on August 3, 2021, with application number CN 202180056741.X and invention title "Time Scale Propagation Using Global Navigation Satellite Systems and Its Application". Technical Field

[0002] This invention relates to a method and system for propagating time signals, and the application of the propagated time-stamped signals. Background Technology

[0003] Precise Point Positioning (PPP) is a technique used to measure the stability of a clock and its frequency offset. Typically, single / dual-frequency carrier phase and code observations from a Global Navigation Satellite System (GNSS) receiver timing with a local oscillator of interest are collected over a sufficiently long period. At least one (e.g., two) PPP processors combine these observations with precise orbit and clock corrections available from commercial operators, public offices (e.g., the International GNSS Service (IGS) or one of its associated analysis centers), and several modeling effects such as Earth's solid tides in a Kalman filter, and estimate the position and clock offset of the GNSS receiver with the local oscillator.

[0004] The clock bias of the local oscillator is of interest for applications requiring precise time / frequency references or involving time / frequency transfer. The PPP process can be considered as a phase detector, aligning the local oscillator of the GNSS receiver with the time scale T. PPP Comparison. T PPP It is a timescale embedded in precise track and clock calibration. The timescale T is defined very frequently without using a high-end oscillator. PPP .

[0005] By processing observations from two separate receivers / clocks, the comparison between the two clocks can be found by simply subtracting the two clock deviations estimated by at least one PPP processor.

[0006] exist Figure 1 The diagram illustrates a typical prior art device comprising multiple GNSS receivers 201 and 202 and their respective clocks, each GNSS receiver-clock combination located at a separate site. The clock of GNSS receiver 201 generates a clock signal T1. The clock of GNSS receiver 202 generates a second clock signal T2. GNSS receivers 201 and 202 are each equipped with antennas 211 and 213, respectively, to receive signals from multiple satellites 205(s) (s = 1, 2, ..., S). Other components specific to each site are described in detail below.

[0007] Local site The clock 212 of the GNSS receiver 201 located at the local site can be a crystal oscillator (crystal-controlled (OC)-XO) 212. The oscillator 212 can be a disciplined oscillator that generates a clock signal T1. The local site also includes multiple (e.g., two) PPP processors 203 and 210, each configured to receive a clock signal T1 from the calibration generator 204 in conjunction with the clock signal T1. PPP The correction signal C(T) PPP ), T PPP Used as a reference clock signal.

[0008] The PPP processor 203 further receives the raw GNSS data signal R5(T1) from the GNSS receiver 201, which depends on the clock signal T1 indicated by R5(T1). Therefore, the PPP processor 203 obtains information about the clock signal T1 from R5(T1). Then, it calculates the reference clock signal T. PPP The difference between the clock signal T1 and the time signal T3 is used to generate the time signal T3 = T. PPP -T1.

[0009] The PPP processor 210 receives the output raw data signal R7(T2) from the GNSS receiver 202 and obtains information about the clock signal T2 from R7(T2), as indicated by R7(T2). The PPP processor 210 can be connected to the communication network 206 via transceiver 220 to receive the signal R7(T2) from a remote site. The output raw GNSS data signals R5(T1) and R7(T2) are calculated based on the signal from at least one satellite 205 and the corresponding clock signals T1 and T2.

[0010] Then, the PPP processor 210 calculates the reference clock signal T. PPP The difference between the clock signal T2 and the time signal T4 is used to generate the time signal T4 = T. PPP -T2. Clock T2 is a timescale propagated from the remote (server) site to the local (client) site. The terms "clock signal," "time signal," and "timescale" are used interchangeably herein and are used to refer to the same meaning. For example, clock signal T1 is a time signal. This will be clear to those skilled in the art.

[0011] The comparator 207 at the local station receives and processes time signals T3 and T4 to generate a time signal T6 = T4 - T3 = (T PPP -T2)-(T PPP -T1) = T1 - T2. Reference clock signal T PPP It is offset in the process.

[0012] The time signal T6 can be used to train the local oscillator 212 so that it closely follows T2. This can be accomplished using a phase-locked loop (PLL) 208 and a digital-to-analog converter 209. Alternatively, a direct digital synthesizer (DDS) can be used to train the local oscillator. Both methods are known to those skilled in the art.

[0013] Figure 1 Separate PPP processors 203 and 210 and a separate comparator 207 are shown; however, as will be apparent to those skilled in the art, they are used to illustrate different functional actions that can be performed by one or more different processors, and the figures are not intended to show any physical limitations.

[0014] remote site The clock 215 of the GNSS receiver 202 located at the remote site can be an atomic oscillator (e.g., an H-maser) 215 configured to generate a time stamp T2. The transceiver 222 of the GNSS receiver 202 is also connected to a communication network 206. The transceiver 222 transmits the raw data signal R7 (T2) to the client site via the network 206.

[0015] The problem to be solved The difference T1-T2 calculated at the local site depends on the accuracy of the remote clock signal T2. An improved remote clock signal T2 with better accuracy and / or stability needs to be received at the local site, and therefore an improved T1-T2 needs to be calculated.

[0016] Furthermore, in the aforementioned prior art devices, a large amount of raw GNSS data R7 with embedded T2 needs to be sent to the PPP processor / local station. This increases the data load on the communication network 206, and therefore requires the communication network 206 to be a high-capacity network. Moreover, if an interruption occurs in data transmission between the local and remote stations, or in the event of a network shutdown, the prior art method may lead to inaccurate analysis. Any interruption exceeding approximately 10-120 seconds will result in a complete reset of the process, which has a long initialization time (half an hour to several hours) during initialization, during which accuracy is reduced. Summary of the Invention

[0017] The purpose of this invention is to address and provide solutions to at least the aforementioned drawbacks and shortcomings of the prior art.

[0018] This invention is defined by the independent claims. Preferred embodiments are further defined by the dependent claims.

[0019] A more precise remote clock signal with embedded time stamp T2 can be used to improve the track and clock correction signal C(T). PPPThe inherent timescale T in ) PPP This improvement can be achieved in the following way: based on information about the precise orbit and clock signal T. PPP The information is used to improve the accuracy of the remote time-stamped signal T2. The improved time-stamped signal T2 can be achieved in the following ways.

[0020] In one aspect of the invention, an improved time-stamped signal T2 can be implemented in the correction signal by implementing the PPP process at a remote site (hereinafter referred to as the server site). The time-stamped signal T2, which is generated by the clock of the receiver at the server site and embeds precise track and clock signals, is transmitted to the local site (hereinafter referred to as the client site).

[0021] In the other hand, the improved T2 is the replacement for T. PPP The precise orbit and clock timing signal is calculated at the server site and incorporates information about clock signal T2, which can be generated by at least one high-precision clock. This high-precision clock can be used to time multiple GNSS receivers. Each server site can collect data from multiple such GNSS receivers and clock stations at different locations. These receivers can be ground reference stations collecting satellite data. Receivers can be timed by a single clock or have their corresponding high-precision clocks. Multiple globally distributed GNSS receivers (ground reference stations) can be used to improve method performance. Furthermore, in the case of multiple server sites, the server sites themselves can be globally distributed.

[0022] Alternatively or otherwise, the modified time signal T2 can incorporate information about a clock signal T2 inherent in the satellite's high-precision clock. This variation enables the calculation of an accurate time signal without requiring a high-precision clock at the GNSS receiver side.

[0023] In another aspect, the improved time signal T2 is achieved by calculating the precise orbital and clock signal T. PPP The clock offset estimate is generated by the difference between the clock signal T1 and the clock signal T2 at the server site. Similar to Example 1, this involves running a PPP process at the server site. The transmission of the clock offset reduces the data load on the communication network, thus resulting in biased information transmission.

[0024] Other aspects and advantages of the invention are described in the following detailed description. Attached Figure Description

[0025] Embodiments of the present invention will now be described with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific embodiments and should be construed as including all variations, modifications, equivalent devices and methods and / or alternative embodiments of the present invention.

[0026] Figure 1 The device is shown as a prior art device.

[0027] Figure 2A A method apparatus according to a first exemplary embodiment of the present invention is shown.

[0028] Figure 2B Another method apparatus according to a first exemplary embodiment of the present invention is shown.

[0029] Figure 3A A method apparatus according to a second exemplary embodiment of the present invention is shown.

[0030] Figure 3B Another method apparatus according to a second exemplary embodiment of the present invention is shown.

[0031] Figure 4A A method apparatus according to a third exemplary embodiment of the present invention is shown.

[0032] Figure 4B Another method apparatus according to a third exemplary embodiment of the present invention is shown.

[0033] Figure 5 A schematic example of a general-purpose computer is shown. Detailed Implementation

[0034] The terms “have,” “may have,” “include,” and “may include” are used herein to indicate the presence of the corresponding feature (e.g., an element such as a number, function, operation, or part) and do not exclude the presence of additional features.

[0035] As used herein, the terms “a or b”, “at least one of a and / or b”, or “at least one of a and / or b” include all possible combinations of the items listed using them. For example, “a or b”, “at least one of a and b”, or “at least one of a or b” means: (1) including at least one a, (2) including at least one b, or (3) including at least one a and at least one b.

[0036] The terms “first” and “second” as used herein can modify various elements regardless of the order and / or importance of the corresponding elements, and do not limit the corresponding elements. These terms can be used for the purpose of distinguishing one element from another. For example, a first element can be referred to as a second element without departing from the scope of the invention, and similarly, a second element can be referred to as a first element.

[0037] It should be understood that when an element (e.g., the first element) is (operably or communicatively) coupled / connected to another element (e.g., the first element) to another element (e.g., the second element), the element can be directly coupled / connected to the other element, and an intermediate element (e.g., a third element) may exist between the element and the other element. Conversely, it should be understood that when an element (e.g., the first element) is "directly coupled / connected" or "directly connected" to another element (e.g., the second element), there is no intermediate element (e.g., a third element) between the element and the other element.

[0038] The expression “configured as (or set to)” as used herein may be used interchangeably with “suitable for,” “compatible with,” “designed to,” “fit for,” “make,” or “capable of.” The term “configured as (or set to)” does not necessarily mean “specifically designed for” at the hardware level. Rather, the expression “device configured as” may mean that the device is “capable” of working with other devices or components in a particular context.

[0039] The terminology used in describing various embodiments of the invention is for the purpose of describing particular embodiments and is not intended to limit the invention. As used herein, the singular form is also used to include the plural form, and unless the context clearly indicates otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms defined in commonly used dictionaries should be interpreted as having the same or similar meaning as in the context of the related art and should not be interpreted as having an ideal or exaggerated meaning unless clearly defined herein. Even terms defined in this invention should not be interpreted as excluding embodiments of the invention.

[0040] A processor is any entity capable of processing parameters. Some examples in this specification include PPP processors, GNSS processors, correction processors, etc., which can be implemented as software or physical devices and can be integrated into the system being protected or located in a cloud computing network. Furthermore, the general term PPP used herein can cover different variations / details of the technology, such as PPP Real-Time Kinematics (PPP RTK), PPP Integer Ambiguity Resolution (PPP IAR), PPP Ambiguity Resolution (PPP AR), etc. Physical processors typically include a central processing unit (CPU) and memory (including any type of memory desired, including one or more of random access memory, read-only memory, programmable memory, etc.). One or more screens (monitors), keyboards, mice, other input devices, printers, etc., may also be provided.

[0041] T PPP It is embedded in the precision track and clock correction signal Cx(T) PPP The time scale in ) . For convenience, Cx is referred to as the precise orbit and clock signal, even though it may contain other information, such as, but not limited to, the troposphere, ionospheric estimation, and UPD (uncalibrated phase delay). It can also be called the PPP correction signal because it represents the correction provided to the PPP processor. T PPP It can also be the result of calculations performed on any processor (e.g., a GNSS processor). Figures 2A-4B The terms "precise track and clock signal" and "PPP correction signal" have the same meaning. The term "precise track and clock pulse" can also refer to the use of T... PPP (e.g., T) PPP + / -Tx) Modify / process or embed T PPP (e.g., T) PPP Any signal within + / -Tx).

[0042] Communication network 206 may enable Wi-Fi, 3G, 4G, or 5G, or some other (future) form of wired or wireless communication. Wireless communication may include cellular communication, including at least one of, for example, LTE, LTE-A, CDMA, WCDMA, UMTS, WiBLO, or GSM. Other standards are not excluded. According to embodiments of the invention, wireless communication may include at least one of, for example, Wi-Fi, Bluetooth, Bluetooth Low Energy, Zigbee, NFC, MST, or radio frequency networks. According to embodiments of the invention, wireless communication may include GNSS. For example, GNSS may be GPS, GLONASS, or the European Global Satellite Navigation System (Galileo). Wired connections may include at least one of, for example, Universal Serial Bus (USB), High Definition Multimedia Interface (HDMI), RS-232, Power Line Communication (PLC), or Common Old Telephone Service (POTS). Networks may include at least one of telecommunications networks, such as computer networks (e.g., Local Area Network (LAN) or Wide Area Network (WAN)), the Internet, or telephone networks. Communication networks may also be configured via satellite communication solutions, whether using geostationary satellites or communication satellites in any other orbit. It can be, for example, a one-way channel allocation from a remote server site to a client site. Fugro uses one-way broadcasts from geostationary satellites.

[0043] All devices disclosed herein may also include transceivers for sending and receiving signals over a communication network.

[0044] As disclosed in this article, client and server architectures are used to represent local and remote architectures, respectively. Clients and servers can be separated by distances ranging from meters to 1,000 kilometers.

[0045] For the purpose of determining the scope of protection conferred by the claims of this document, any element equivalent to the element specified in the claims should be considered.

[0046] Example 1 Figure 2A A method apparatus according to a first exemplary embodiment of the present invention is shown. The apparatus includes at least one client site and one server site.

[0047] (Multiple) client sites At client sites, the method includes running at least one client GNSS procedure in a GNSS receiver 201(c) (c = 1, 2, ..., C).

[0048] The first client site includes a GNSS receiver 201(1) timed by a clock 212(1) (internal / external). The clock 212(1) is configured to generate a time signal T1(1), which is input to the GNSS receiver 201(1). The clock 212(1) may include a crystal oscillator, which may be, for example... Figure 1 The prior art device shows a tunable oscillator. The GNSS receiver 201 (1) receives signals from at least one satellite 205 (s = 1, 2, ..., S) using antenna 211 (1). It calculates the output GNSS raw data signal R5 based on the received satellite signal and clock signal T1 (1), and is therefore indicated by R5 (T (1)) in the figure, and provides R5 to the PPP processor 203 (1). T1 (1) may be embedded in the measurement data of the GNSS receiver 201 (1) transmitted to the PPP processor 203 (1).

[0049] The PPP processor 203(1) can obtain information (e.g., values) about the clock signal T1(1) from the output raw data signal R5. The processor 203(1) is connected to the communication network 206 and receives an improved correction signal C8(T2), which is embedded with the time stamp signal T2 via the network 206. It processes the received improved correction signal C8(T2) and the raw data signal R5(T1(1)) to generate an improved time signal offset T1(1)-T2.

[0050] In the case of multiple client sites c, the c-th client site includes a GNSS receiver 201(c) with an antenna 211(c) and timed by a clock 212(c). A PPP processor 203(c) uses the raw data signal R5(T1(c)) output from the receiver 201(c) to obtain information about the time signal T1(c) generated by the clock 212(c). The processor 203(c) is coupled to the same communication network 206 and also receives an improved correction signal C8(T2) via this network. It further processes the improved correction signal C8(T2) and the raw data signal R5(T1(c)) to generate an improved time signal offset T1(c)-T2.

[0051] PPP processors 203(1), 203(c) and any other C-2 PPP processors at the C client sites can further exchange their respective difference signals T1(1)-T2, T1(c)-T2. This allows each PPP processor 203(1), 203(c) to evaluate the deviation of its calculated difference signal from the difference signals obtained at other client sites.

[0052] By comparing the first difference signal (T1(1)-T2) with the second difference signal (T1(c)-T2), the deviation between the first difference signal T1(1)-T2 and any one of the c-th difference signals T1(c)-T2 can be further analyzed.

[0053] Any of the GNSS receivers 201(c) can be implemented by any GNSS receiver device known in the prior art. However, the invention is not limited thereto. Moreover, future implementations can be applied to devices according to the invention. This applies to all the drawings of the invention.

[0054] The PPP processor 203(c) can be implemented by any general-purpose computer known in the art on which the PPP process is running, by a dedicated computer, or embedded within the firmware of a GNSS receiver. Figure 5 The diagram illustrates the general setup of this type of general-purpose computer.

[0055] server site At the server site, the method includes running a server GNSS procedure. The method also includes running a server PPP procedure and generating precise orbit and clock signals (embedded with an improved T2), which are broadcast to at least one client.

[0056] The server site includes a GNSS receiver 202 with an antenna 213 and timed by a precision clock 230. The clock 215 can be more precise than the clock 212(c) at the client site and generates a clock signal T2. For example, it can be an atomic oscillator, such as an H-maser. The GNSS receiver 202 is configured to generate an output raw data signal R7 that combines information about the clock signal T2, which is therefore indicated by R7(T2), and the received satellite signal.

[0057] R7(T2) is the measurement data of GNSS receiver 202, also known as GNSS raw data signal or simply raw data.

[0058] At the server site is a PPP processor 210, which receives the output raw data signal R7 having T2 embedded.

[0059] PPP processor 210 is further configured to receive a PPP correction signal C(T) representing the precise track and clock signal. PPP ).

[0060] Each satellite signal includes an estimated position and an estimated clock offset from the corresponding GNSS satellite from which it is broadcast. PPP correction signal C(T) PPP C(T) is a time series of correction values ​​to account for these estimated satellite position, orbit, and clock biases. PPP The PPP correction signal C(T) can be provided using an external / internal correction generator 204, where the term "external / internal" indicates the location of the reference server site. Typically, the PPP correction signal C(T) is provided at regular intervals (e.g., 10 seconds). PPP ), and the PPP correction signal C(T) PPP This includes a complete set of correction values ​​for each satellite.

[0061] In signals R7(T2) and C(T) PPP When ) is used as input, the PPP processor 210 generates a clock bias signal, or in other words, generates a server offset signal T4 (T PPP -T2).

[0062] T4(T) PPP -T2) is input to the correction processor 214. The correction processor 214 also receives the PPP correction signal C(T) from the correction generator 204. PPP The calibration processor 214 then replaces the PPP timescale signal T with the server offset signal T4. PPP This is used to generate C8 (with an improved timescale T2). Therefore, C8 can be considered as the precise track and clock signal C(T). PPP In this context, the time stamp of clock signal T2 is embedded and therefore indicated by C8(T2). The correction processor 214 receives the time stamp from each satellite embedded in C(T2). PPP Subtract the offset signal T4 from the precise clock correction value in C(T). PPP If the difference between C(T) and T4 is below a predetermined threshold, further correction may not be necessary. However, if C(T) PPP If the difference between the offset signal T4 and the timescale of the clock exceeds a predetermined threshold, additional correction can be made when the clock timescale is changed. For example, a GNSS satellite traveling at approximately 4 km / s, and the time it takes for the satellite to move one millimeter, can be defined as a threshold when additional action is required. In this example, the threshold becomes 250 ns. If the offset signal T4 exceeds this limit, the timescale of the combined precise orbit coordinates can be offset by the amount that compensates for the clock offset. Alternatively, the precise orbit coordinates can be recalculated using the correct / offset clock timescale.

[0063] Therefore, the process executed by the calibration processor 214 can be summarized as follows. The calibration process determines the precise track and clock offset signal T9 (T) by combining the two signals. PPP The clock offset caused by -T2) exceeds a predetermined threshold; and if it is determined to be yes, the correction process corrects the clock offset so that the track and clock remain constant, for example, by: o shifts the timestamp of the combined precise orbital coordinates by a certain amount, said amount compensating for the clock offset; or o Recalculate the precise orbital coordinates under the offset clock scale.

[0064] Then, C8(T2) is sent to each client site via the communication network (206).

[0065] Each of the PPP processor 210 and the correction processor 214 can be generated by, for example Figure 5 The different general-purpose computer implementations shown are illustrated. However, in this embodiment, the correction processor 214 and the PPP processor 210 can be implemented by a single computer, in which case T4 (T PPP The generation of -T2) and C8(T2) is performed by the same entity.

[0066] As described above, the PPP processor 203(c) at the client site c processes R5(T1(c)) and C8(T2) to obtain T1(c)-T2.

[0067] Figure 2B Another method apparatus according to a first exemplary embodiment of the present invention is shown. The apparatus includes at least one client site and multiple server sites.

[0068] Client site This implementation method is similar to the one described in the description Figure 2A The implementation is the same on some client sites.

[0069] server site The server site may include a primary site and at least one secondary site. In addition to a GNSS receiver 202(1) with an antenna 213(1) timed by a precision clock 215(1), a PPP processor 210(1), a correction generator 204, and a correction processor 214, as already described... Figure 2A As in some server devices, the main server site may also include combiner unit 216.

[0070] The auxiliary site includes a GNSS receiver 202(i) (i = 1, 2, ..., I), which has an antenna 213(i) timed by a precision clock 215(i) and a PPP processor 210(i). Each PPP processor 210(i) receives a PPP correction signal C(T) representing the precision orbit and clock signal. PPP C(T) can be provided using at least one external / internal correction generator 204. PPP Each PPP processor 210(i) generates a clock bias; in other words, the server offset signal T4 = T PPP -T2(i).

[0071] The combiner unit 216 at the main site acts as an intermediate unit between the correction processor 214 and the PPP processor 210(1). Assuming there are I server sites, the combiner unit 216 is configured to receive server offset signals T4 = T from the main site and the PPP processors 210(1), ..., 210(I) of the I-1 sites. PPP -T2(i) (i = 1, 2, ..., I). T4(T) from the secondary server site PPP -T2) The output signal can be received via broadcast transmission and / or via any suitable telecommunications network.

[0072] In an embodiment, combiner unit 216 operates a process that can combine signals from several different clocks weighted in a statistically optimal manner. Combiner unit 216 can take into account the different short-term and long-term performance of each clock signal to be combined. For example, some clocks 215(i) may have relatively poor short-term performance but good long-term performance, while the opposite may be true for other clocks 215(i). Those skilled in the art will know how to implement such combiner unit 216 to output the optimal possible composite clock or integration time. Combiner unit 216 receives output signals T4(T) from all PPP processors 210(i) at different server sites. PPP -T2(i)), and generate the combined server offset signal T9(T PPP -T2). T9 can be considered as the precise orbit and timescale T. PPP The correction involves embedding a time stamp for the clock signal T2. Unit 216 can be located at any of the I server sites (e.g., the master server site), in which case the signal T4 from the other I-1 server sites is routed to the master site. Alternatively, unit 224 can be located away from all server sites, in which case the signal T4 (T...) from all server sites... PPP -T2) can be sent to a remote site containing unit 216.

[0073] In one embodiment, the combiner unit 216 can also be located outside the main server site, such as in a cloud computing system. In this case, T4 (T PPP -T2(i)) signals are sent from all PPP processors 210(i), including PPP processor 210(1) of the master server site, to combiner unit 216.

[0074] Combined server offset signal T9 (T PPP -T2) and C(T) from the correction generator 204 PPP Together, they are input to the correction processor 214. If the combiner unit 216 is located outside the main site (or any other server site), then T9 (T PPP -T2) is transmitted to the correction processor 214, and such transmission can be via any suitable telecommunications network. It can be broadcast.

[0075] The correction processor 214 uses a combined server offset signal T9 (T PPP -T2) Modify the PPP correction signal C(T) PPP To generate C8 (with improved timescale T2). For example... Figure 2A In this context, C8(T2) can therefore be considered a precise track and clock signal, in which the time stamp of the clock signal T2 is embedded.

[0076] Then, C8 is broadcast to each client site via communication network 206.

[0077] At each client site c, the PPP processor 203(c) processes R5(T1(c)) and C8(T2) to obtain T1(c)-T2. This is similar to... Figure 2A The equipment.

[0078] The combination of clock biases from multiple PPP processors helps to achieve a more stable T9 (T PPP -T2), which will result in C8(T2) with an improved timescale T2. This is because it is assumed that a high-side oscillator is not used to define T. PPP Therefore, timescale T2 is longer than T. PPP More stable. This is often the assumption when generating orbit and clock corrections for positioning and navigation purposes, because the stability of the timescale has no impact on such applications.

[0079] Each of the PPP processor 210(i) and the correction processor 214 can be generated by, for example Figure 5 Different general-purpose computer implementations are shown. However, in the embodiments, the correction processor 214 and the PPP processor 210 (1) can be implemented by a single computer, in which case T4 (T PPPThe generation of -T2(l)) and T8 is performed by the same entity.

[0080] R7 (T2 (i)) data can also be collected from different GNSS receivers 202 (i) at different server sites via one or more PPP processors at any site. There may be practical reasons to choose this approach if the communication line is robust and has high capacity, even if the communication line would require less data capacity and be more robust for the aforementioned approach. Furthermore, the PPP processor 202 (i), correction processor 214, and / or combiner unit 216 can be co-located or non-co-located.

[0081] Example 2 Figure 3A A method apparatus according to a second exemplary embodiment of the present invention is shown.

[0082] like Figure 2A , Figure 2B As in the embodiments, the device may include one or more server sites. Each server site may be configured to receive raw data signals from a plurality of geographically distributed GNSS receivers 202(i) (e.g., 25-50, preferably 50-100, more preferably greater than 100). These receivers 202(i) may be ground reference stations that collect satellite data from satellite 205. The GNSS receivers 202(i) may be locally timed by a low-precision local oscillator or a high-precision clock 215(i). In this embodiment, at least one of the receivers 202(j) is timed by a high-precision clock. A plurality of globally distributed GNSS receivers 202(i) (ground reference stations) may be used to improve method performance. In the case of multiple server sites, the server sites themselves may be globally distributed.

[0083] Figure 3A An example is shown in which the equipment includes a server site having I GNSS receivers 202(i), wherein each receiver 202(i) uses a corresponding precision clock 215(i) and at least one client site for timing.

[0084] Client site At (multiple) client sites, the method includes running a client GNSS procedure, the implementation of which is similar to that in [the context of]... Figure 2A or Figure 2B The implementation is the same at (multiple) client sites described in part of the device description.

[0085] server site Figure 3AI GNSS receivers 202(i) with antennas 213(i) are shown, each antenna being timed by a precision clock 215(i). The precision clock 215(i) generates a clock signal T2(i) respectively.

[0086] The method includes running a server GNSS process. It also includes calculating the precise orbit and clock signal C10 using timescale T2 and broadcasting it.

[0087] Each GNSS receiver 202(i) generates an output GNSS raw data signal R7(T2(i)), and each R7(T2(i)) is embedded with information about the precise clock T2(i) of the corresponding GNSS receiver.

[0088] The GNSS processor 218 receives signals R7(T2(i)) from the corresponding I GNSS receivers and calculates the precise orbit and clock signal C10(T2). The precise clock information or time stamp T2 is embedded in the calculated precise orbit and clock signal T10(T2).

[0089] Then, the GNSS processor 218 broadcasts C10(T2) to each client site via the communication network 206, where it is received and processed by the PPP processor 203(c). Therefore, in Figure 3A In this embodiment, the PPP processor 203(c) does not receive a separate time signal T. PPP Instead of receiving -T2, it only receives the improved correction signal C10(T2) from the server site.

[0090] GNSS processors can be made by, for example Figure 5 The general-purpose computer shown is used to implement this.

[0091] Figure 3B Another method apparatus according to a second exemplary embodiment of the present invention is shown.

[0092] Client site This implementation method is similar to... Figure 2A or Figure 2B or Figure 3A The implementation is the same at (multiple) client sites described in part of the device description.

[0093] server site server site and Figure 3A The difference is that, instead of the information of the precise clock 215(i) embedded in the GNSS receiver 202(i), the method uses the clock information of the internal satellites 205(1), 205(2), ..., 205(S) to calculate the precise orbit and clock signal.

[0094] exist Figure 3B In this system, each satellite 205 has its own internal precision clock (not shown), which generates a satellite clock signal T2s(s) to provide timing information about when satellite 205(s) transmits radio signals. Each GNSS receiver 202(i) generates a raw data signal R7 based on the satellite radio signals received from satellite 205, embeds the inherent time signal T2s(s) associated with the satellite clock into its measurement data, and sends the corresponding output signals R7 (T2s(l)...T2s(s)) to GNSS processor 218. Then, when calculating the precision orbit and clock signal C10(T2), the satellite clock information T2s(s) is extracted from R7(T2s(s)) by GNSS processor 218. The extracted precision clock information T2 is embedded in the calculated C10(T2). C10, or the precision orbit and clock signal, is broadcast to each client site via communication network 206.

[0095] GNSS processor 218 generates accurate orbits and clocks for real-time use based on GNSS reference station data as input. Such processors are well known to those skilled in the art, and many different implementations exist. The Real-Time Gipsy (GNSS Inference Positioning System) developed by JPL NASA (Jet Propulsion Laboratory, National Aeronautics and Space Administration) in the United States is an example of such an implementation. For example, GNSS processor 218 can be implemented in a Kalman filter, where satellite orbital position and clock offset are estimated in real time. Alternatively, the orbit can be estimated using a least-squares process running, for example, in hourly batches. This yields an orbit prediction, while the clock offset can be calculated, for example, using the predicted orbit, reference station coordinates, and the same GNSS reference station data as input. Orbit and clock calculations are high-level processes involving the estimation of many different inputs, models, and variables. Models and inputs can include, for example, solid Earth tides, ocean loading, Earth rotation and orientation, satellite solar pressure models, satellite attitude models, correlation effects, etc. The estimated parameters may include, for example, adjustments to known reference station coordinates, receiver and satellite signal offsets, tropospheric delay at each reference station, reference station clock offset, ionospheric delay, satellite orbit, and satellite clock offset.

[0096] Therefore, a precise timescale T2 can be achieved using only GNSS observations, without having a precise clock 215(i) at each reference station (GNSS receiver). With Figure 3A Similar to the embodiments, the PPP processor 203(c) does not receive a separate correction signal C1(T). PPP Instead, it receives track and clock signals with an improved time stamp C10 (T2) from the server site.

[0097] GNSS processors can be made by, for example Figure 5 The general-purpose computer shown is used to implement this.

[0098] Example 3 Figure 4A A method apparatus according to a third exemplary embodiment of the present invention is shown. The apparatus includes at least one client site and one server site.

[0099] In this embodiment, the improved time signal T2 is a clock offset estimate T4, which is calculated by retrieving the precise track and clock timescale T. PPP It is generated by the difference between the two and the clock signal T2 of the precise clock 215 at the server site.

[0100] Client site At (multiple) client sites, the method includes running at least one client GNSS procedure.

[0101] The first client site includes a GNSS receiver 201(1) with an antenna 211(1) timed by a clock 212(1). The clock 212(1) generates a clock signal T1(1). The raw data signal R5 output by the GNSS receiver 201(1), which includes information about this clock signal T1(1), is input to the PPP processor 203(1).

[0102] The PPP processor 203(1) also receives the PPP correction signal C(T) from the correction generator 204. PPP The correction generator 204 can be located inside the device, or, for example, outside it as part of a cloud computing network. Then, the PPP processor 203(1) calculates T. PPP The difference between the extracted T1(1) and the T3(l) is used to generate T3(l) = T PPP -T1(1).

[0103] The first client site also includes a comparator 207(l), which is configured to receive T3(l) from the PPP processor 203(1). Figure 4A In this embodiment, the physical PPP processor 203(1) and comparator 207(l) are shown as integrated within a single PPP processor module 221(1). In one embodiment, physical entities 203(1) and 207(l) may be located in separate modules. Furthermore, they may exist in software and / or hardware implementations, for example... Figure 5 The implementation shown is illustrated in the figure.

[0104] Comparator 207(l) is connected to transceiver 220(1), which is connected to communication network 206. It receives T4(T) from the server site via the network 206 and transceiver 220(1). PPP -T2), that is, the difference between the precise track and clock time scale and the more precise clock signal T2.

[0105] Comparator 207(l) generates a time difference signal T11(1) = T3(1) - T4 = T1(1) - T2.

[0106] In one embodiment, the order of processes within the PPP processor module 221(1) can be changed, such that signal T4(T PPP -T2) is used in conjunction with C(T) PPP R5 (T1(1)) and R5 (T1(1)) are input into PPP processor 203(1) so that T11(1) is output directly from PPP processor 203(1). This example can be understood as having a correction processor (not shown) in front of PPP processor 203(1) that replaces comparator 207 and is located at the client site.

[0107] In this embodiment, the device includes multiple (C) client sites.

[0108] For example, the c-th client site includes a GNSS receiver 201(c) with an antenna 211(c) and timed by a clock 212(c). The PPP processor 203(c) uses the raw data signal R5(T1(c)) output from the receiver 201(c) to obtain information about the time signal T1(c) generated by the clock 212(c).

[0109] The PPP processor 203(c) also receives the PPP correction signal C(T) by using the correction generator 204. PPP Then, PPP processor 203(c) calculates T. PPP The difference between T1(c) and T3(c) is used to generate T3(c) = T PPP -T1(c).

[0110] Comparator 207(c) receives T3(c) from PPP processor 203(c) and is connected to transceiver 220(c), which is connected to communication network 206. It receives clock signal T4(T) via this network. PPP -T2). It further subtracts the input time signal to generate an improved time signal offset T11(c) = T1(c) - T4 = T1(c) - T2. Therefore, signal T4 (i.e., the precise track and clock time scale T) PPP The difference between T and the more precise clock signal T2 can be considered as a function of T.PPP Time scale correction.

[0111] Comparators 207(l), 207(c) and / or any other c-2 comparators at the c client sites can further exchange their respective difference signals T11(1) = T1(1)-T2, T11(c) = T1(c)-T2..., such that each comparator 207(l), 207(c) can evaluate the deviation of its calculated difference signal from the difference signal obtained at other client sites.

[0112] server site At the server site, the method includes running a server GNSS procedure. The method also includes running a server PPP procedure and generating a time-corrected signal T4, which includes an improved T2 signal broadcast to one or more clients.

[0113] Compared with Example 1 ( Figure 2A , Figure 2B Similarly, this embodiment relates to running a PPP process at a server site. The server site includes a GNSS receiver 202 with an antenna 213 and is clocked by a precision clock 230. Clock 215 generates a clock signal T2. For example, it can be an atomic oscillator, such as an H-maser. The GNSS receiver 202 is configured to generate an output raw data signal R7(T2) that combines information about the clock signal T2 and one or more received satellite signals. The raw data R7(T2) is the measurement data of the GNSS receiver 202.

[0114] The server site also includes a PPP processor 210, which receives the raw data signal R7(T2) and extracts T2 from R7(T2). The PPP processor 210 is further configured to receive a PPP correction signal T from the correction generator 204. PPP The correction generator 204 can again be located inside or outside the server site. The PPP processor 210 generates T... PPP Time-scaled correction signal, also known as T PPP -T2 server offset signal T4 (T PPP -T2).

[0115] In this embodiment, the time offset signal T4 is calculated as a time offset signal embedded within the precision track and clock signal. PPP Correction.

[0116] PPP processor 210 is connected to transceiver 222, which broadcasts T4 (T) via communication network 206. PPP -T2).

[0117] Figure 4BAnother method apparatus according to a third exemplary embodiment of the present invention is shown. The apparatus includes at least one client site and multiple server sites.

[0118] Client site The methods and implementation of the device at the client site are similar to those at the client site. Figure 4A The methods and implementations described in the description are the same.

[0119] server site Assume there are I server sites, each including a GNSS receiver 202(i) with an antenna 213(i) and timed by a precise clock 215(i) that generates a clock signal T2(i). The GNSS receiver 202(i) is configured to generate an output raw data signal R7(T2(i)) that combines information about the clock signal T2(i) and one or more received satellite signals. T2 is embedded in the measurement raw data of the GNSS receiver 202(i).

[0120] like Figure 4A As shown, the server site also includes a PPP processor 210(i), which receives the GNSS raw data signal R7(T2(i)). The PPP processor 210(i) is further configured to receive a PPP correction signal C(T) from the correction generator 204. PPP ), PPP processor 210(i) then generates server offset signal T4(T PPP -T2(i)).

[0121] The correction generator 204 provides the same PPP correction signal C(T) to all PPP processors 210(i). PPP ).

[0122] The device also includes a combiner unit 224, which operates a process that can combine signals from several different clocks weighted in a statistically optimal manner. The combiner unit 224 can take into account the different short-term and long-term performance of each clock signal to be combined. For example, some clocks 215(i) may have relatively poor short-term performance but good long-term performance, while the opposite may be true for other clocks 215(i). Those skilled in the art will know how to implement such a combiner unit 224 to output the optimal possible composite clock or integration time. The combiner unit 224 receives output signals T4(T) from all PPP processors 210(i) at different server sites. PPP -T2(i)), and generate the combined server offset signal T9(T PPP -T2). T9 can be considered as the precise orbit and timescale T. PPPThe correction is performed, wherein a time stamp of clock signal T2 is embedded. Unit 224 can be located at any of the I server sites (e.g., the main server site), in which case signals T4 from the other I-1 server sites are routed to the main site. Alternatively, unit 224 can be located away from all server sites, in which case signals T4 (T2) from all server sites are routed to the main site. PPP -T2) can be sent to a remote site containing unit 224.

[0123] Combiner unit 224 is connected to transceiver 222, which transmits server offset signal T9, which can be regarded as a correction to achieve modified accurate track and clock timing for each client site via communication network 206.

[0124] In all embodiments, clock 212(c) may include inexpensive crystal oscillators. Differential signals T1(c)-T2 may be input to each of these oscillators via a feedback loop. The feedback loop may include a PLL and a DAC, such as... Figure 1 As shown, details are omitted because they are known to those skilled in the art.

[0125] Because of the precise and stable T2 and therefore T1-T2, the difference signal can be used in a very accurate manner for a disciplined oscillator.

[0126] Similar to Figure 2B R7 (T2 (i)) data can also be collected from different GNSS receivers 202 (i) at different server sites via a single PPP processor located at the main server site. That is, all PPP processors 202 (i) and combiner unit 224 are then co-located. If the communication line is robust and has high capacity, there may be practical reasons to choose to do so, even if it will require less data capacity and be more robust than the above approach.

[0127] Now, let's make some concluding statements.

[0128] According to one aspect of the present invention, a client GNSS facility for receiving a propagated timescale T2 according to Embodiments 1 and 3 includes: at least one GNSS receiver 201(c), at least one PPP processor 203(c), and at least one clock 212(c). Each GNSS receiver 201(c) is configured to generate a client GNSS output raw data signal R5 based on a client clock signal T1(c) and based on one or more satellite signals. The client clock signal T1(c) is generated by the clock 212(c). Each PPP processor 203(c) is connected one-to-one with each GNSS receiver 203(c) and is configured to receive a precise orbit and clock signal. This precise orbit and clock signal corresponds to signal C8(T2) in Embodiment 1 and C8(T2) in Embodiment 3. PPP ).

[0129] Then, the PPP processor 203(c) generates the difference signal (T1(c)-T2) between the client clock signal T1(c) and the time stamp signal T2 based on the client GNSS output raw data signal R5(T1(c)) and the precise orbit and clock signal.

[0130] In embodiment 3, the PPP processor 203(c) is further configured to receive the PPP correction signal C1(T). PPP And generate the PPP time stamp T. PPP The clock offset signal T3(c) between the client clock signal T1(c) and the clock offset signal T4(c). This is determined by comparing the PPP clock offset signal T3(c) with the timescale correction signal T4(c). PPP -T2) or T9 (T PPP -T2), to obtain the difference signal T11(c). This can be done by the PPP processor 203(c) or a separate comparator 207(c). The PPP processor 203(c) and the comparator 207(c) can form a single entity 221(c) or they can be distributed. The PPP correction signal C1(T) is provided via an internal or external correction generator 204. PPP ).

[0131] In Example 3, the client receives the time signal offset T via a communication network. PPP -T2. This reduces the data load on communication network 206, because it is related to T9 (T PPP The data related to -T2 is significantly smaller than the raw GNSS data R7(T2) (e.g., ...). Figure 1 (as broadcast in the prior art shown), and will also provide more satisfactory analysis, even in the event of interruptions in data transmission between client and server devices, or in the event of a temporary network shutdown.

[0132] In both embodiments, clock 212(c) may include a disciplined oscillator configured to generate the client clock signal T1(c) based on the difference signal T1(c)-T2, the former serving as a feedback signal.

[0133] In both embodiments, the PPP processor 203(c) can be configured to exchange generated difference signals T1(c)-T2 with another client GNSS device (e.g., via a transceiver). Thus, the PPP processor 203(1) of the first client GNSS device can compare the generated difference signals T1(1)-T2 with the difference signals T1(2)-T2 generated by the PPP processor 203(2) of the second client GNSS device. Such comparisons between many time signals can, for example, be used to define an integrated timescale such as tai (International Atomic Temperature) or utc (Coordinated Universal Time).

[0134] According to another aspect of the invention, the server GNSS facility equipment for propagating time-stamped signal T2 according to Embodiments 1 and 3 includes at least one GNSS receiver 202 and at least one processor, such as a PPP processor 210. Each GNSS receiver 202 is configured to generate a server GNSS output raw data signal R7 based at least on one or more satellite signals and based on a precise server clock signal T2. The processor is configured to receive a PPP correction signal C1 (T) from an internal / external correction generator 204. PPP It is based on the server's GNSS output raw data signal R7 and PPP correction signal C1 (T) PPP Generate server offset signal T4 (T PPP -T2). The processor generates precise track and clock offset signals T4 (T PPP -T2). This timescale offset signal corresponds to T4 (T) in Example 3. PPP -T2) or T9 (T PPP -T2). In Example 1, C8(T2) includes an improved time-stamped signal T2 within the precision track and clock.

[0135] In embodiment 1, the processors can be configured separately as PPP processor 210 and correction processor 214. Correction processor 214 and the PPP processor can form part of a single processor entity, or as... Figure 2A or Figure 2B The locations shown are discrete. PPP processor 210 receives PPP correction signal C1(T) from internal / external correction generator 204. PPP It is based on the server's GNSS output raw data signal R7(T2) and PPP correction signal C1(T). PPP Generate time-scaled correction signal T4 (TPPP -T2). Then, the correction processor 214, based on the server offset signal T4 (T received from the correction generator 204) PPP -T2) and PPP correction signal C1 (T PPP Generate precise track and clock signals C8(T2).

[0136] In both embodiments, the processor may further include a combiner unit 216 that combines multiple time-scaled offset signals T4 (T) from a PPP processor of another server GNSS device before inputting the results to the correction processor 214. PPP -T2(i)). The combiner unit 216 can also be located externally, for example in a cloud computing system.

[0137] The server GNSS equipment also includes a transceiver to broadcast the precise orbit and clock signal offset signal, such as T4 (T), via telecommunications network 206. PPP -T2) or precise track and clock signal C8 (T2).

[0138] Furthermore, according to one aspect of the invention, a client GNSS facility for receiving the propagation timescale T2 according to Embodiment 2 includes: at least one GNSS receiver 201(c), at least one PPP processor 203(c), and at least one clock 212(c). Each receiver is configured to generate a client GNSS output raw data signal R5(T1(c)) based on the client clock signal T1(c) and based on one or more second satellite signals. The client clock signal T1(c) corresponds to the clock signal generated by clock 212(c).

[0139] Each PPP processor 203(c) is connected in a one-to-one correspondence with each GNSS receiver 203(c). The PPP processor is configured to receive the GNSS output raw data signal R5(T1(c)) and the precise orbit and clock signal C10(T2), extract the time stamp signal T2, and calculate the difference signal T1(c)-T2 between the client clock signal T1(c) and the time stamp signal T2. The GNSS output raw data signal R5(T1(c)) is provided by the GNSS receiver 201(c), and the precise orbit and clock signal C10(T2) is obtained from the server via the communication network 206.

[0140] Clock 212(c) may include a disciplined oscillator 212(c) configured to generate the client clock signal T1(c) based on the difference signal T1(c)-T2 and by using the difference signal as a feedback signal.

[0141] Furthermore, the PPP processor 203(c) can be configured to exchange generated difference signals (T1(c)-T2) with another client GNSS device (e.g., via a transceiver). The PPP processor 203(1) of the first client GNSS device can then compare the generated difference signals (T1(1)-T2) with the difference signals T1(2)-T2 generated by the PPP processor 203(2) of the second client GNSS device. Such comparisons between many time signals can, for example, be used to define integrated time scales, such as tai (International Atomic Temperature) or utc (Coordinated Universal Time).

[0142] According to another aspect of the invention, the server GNSS facility equipment for propagating the time-stamped signal T2 according to embodiment 2 includes a plurality of GNSS receivers 213(i), each receiver being configured to generate a server GNSS output raw data signal R7(T2(i)) based on at least one or more first satellite signals. A processor (e.g., GNSS processor 218) is configured to generate a precise orbit and clock signal C10(T2) based on all server GNSS raw data signals R7(T2(i)), the clock signal C10(T2) embedding the time-stamped signal T2. The processor (e.g., via a transceiver) broadcasts C10 to a client via a communication network 206.

[0143] Each GNSS receiver 213(i) is configured to generate a server GNSS output raw data signal R7(T2(i)) based on a precise clock signal T2(i) (e.g., an atomic clock signal). In an embodiment, the precise clock signal may be a clock signal generated by the precise clock (e.g., an atomic clock) of at least one or all of the plurality of GNSS receivers. Alternatively or in another embodiment, the precise clock signal may be a clock signal generated by the precise clock inherent to at least one satellite 205.

[0144] Preferably, multiple GNSS receivers are distributed globally for improved time propagation performance (achieved through better geometry for accurate orbit calculations and redundant tracking of satellites in all possible orbital locations).

[0145] Figure 5 A general-purpose computer 500 is shown, which can be configured to perform the methods described in any of the above embodiments. The computer may be part of a client or server device.

[0146] Computer 500 includes a processor 501, which can be configured to perform any of the steps described in Embodiments 1 to 3. The processor can operate as a central processing unit or have distributed functionality. It can include integrated circuits (ICs), microcontrollers, programmable logic controllers, dedicated processors, digital signal processors, and / or any other programmable circuits. Computer 500 also includes a memory 502, which is configured to store data in relation to any of the described steps. The memory can include volatile and / or non-volatile memory. Storage devices can include random access memory (RAM), read-only memory (ROM), one or more hard disk drives, optical drives, solid-state storage devices, and / or other suitable memory elements. Computer 500 may also include an input module 503, which can be configured to operate using different user input methods (e.g., touchscreen, gesture control, etc.). It can also receive and / or transmit data via a communication module 5045. The computer also includes an output display configured to display intermediate and / or final results of time-stamp propagation. All components are interconnected via a bus 506.

[0147] While the invention has been described with reference to the exemplary embodiments described above, various changes and modifications may be suggested to those skilled in the art. For example, those skilled in the art will understand that although the invention has been described in the context of hydrogen microwave transmitters, the method can also be used with any cesium or rubidium standard. The invention is intended to cover such changes and modifications that fall within the scope of the appended claims.

Claims

1. A method for propagating a time-stamped signal (T2) from at least one server site to at least one client site, characterized in that, The method includes: Multiple server-side global navigation satellite system (GNSS) processes (202(i), i = 1, 2, ..., I) are run at different locations. Each GNSS process is configured to generate a server-side GNSS output raw data signal (R7(T2(i)); R7s(T2(s))) based on at least one or more received first satellite signals. At the at least one server site, the raw data signal output by the Global Navigation Satellite System is received (R7(T2(i)); R7s(T2(s))). At the at least one server site, a precise orbit and clock signal (C10(T2)) embedded with the time stamp signal (T2) is generated based on the raw data signals (R7(T2(i)); R7s(T2(s))) output by the multiple server global navigation satellite systems; and the precise orbit and clock signal (C10(T2)) is broadcast from the at least one server site to the at least one client site via a telecommunications network (206); At each client site, a client global navigation satellite system process (201(c)) is run, which is configured to generate a client global navigation satellite system output raw data signal (R5(T1(c))) based on a client clock signal (T1(c)) and one or more second satellite signals, and a client precise point positioning PPP process (203(c)) is run, which is configured to receive the client global navigation satellite system output raw data signal (R5(T1(c))) and the precise orbit and clock signal (C10(T2)) via the telecommunications network (206), and generate a difference signal (T1(c)-T2) between the client clock signal (T1(c)) and the time-stamped signal (T2).

2. The method as described in claim 1, characterized in that, At least one of the server global navigation satellite system processes (202(i)) is configured to also generate the server global navigation satellite system output raw data signal (R7(T2(i))) based on a precise clock signal (T2; T2(i)), the precise clock signal being like an atomic clock signal and more accurate than the client clock signal (T1(c)).

3. The method according to claim 1 or 2, characterized in that, At at least one of the client sites, the client clock signal (T1(c)) is generated by a trained oscillator (212) based on the difference signal (T1(c)-T2) as a feedback signal.

4. The method as described in claim 2, characterized in that, The precise clock signal (T2(i)) includes clock information of the Global Navigation Satellite System receiver clock (215(i)) and / or at least one satellite clock.

5. The method according to claim 1 or 2, characterized in that, The at least one server site includes multiple globally distributed Global Navigation Satellite System receivers.

6. The method as described in claim 1 or 2, characterized in that, The method includes: At the first client site, a first difference signal (T1(1)-T2) is generated between the first client clock signal (T1(1)) and the time stamp signal (T2). At the second client site, a second difference signal (T1(c)-T2) is generated between the second client clock signal (T1(c)) and the time stamp signal (T2), and The first difference signal (T1(1)-T2) is compared with the second difference signal (T1(c)-T2).

7. A system for propagating a time-stamped signal (T2), characterized in that, The system includes: Multiple server-based global navigation satellite system receivers (202(i), i = 1, 2, ..., I) operating at different locations are configured to generate server-based global navigation satellite system output raw data signals (R7(T2(i)); R7s(T2(s))) based on at least one or more received first satellite signals. At least one global navigation satellite system processor (218) located at at least one server site, the global navigation satellite system processor being configured to: Receive the raw data signal output by the global navigation satellite system (R7(T2(i)); R7s(T2(s))); Based on the raw data signals (R7(T2(i)); R7s(T2(s))) output by multiple servers from the global navigation satellite system, a precise orbit and clock signal (C10(T2)) embedded with the time stamp signal (T2) is generated; and The precise orbit and clock signal (C10(T2)) is broadcast to at least one client site via a telecommunications network (206); At least one client device, said at least one client device being located at at least one client site, each client device comprising: A client-side global navigation satellite system receiver (201(c)) is configured to generate a client-side global navigation satellite system output raw data signal (R5(T1(c))) based on a client-side clock signal (T1(c)) and one or more second satellite signals. The client-side precise point positioning PPP processor (203(c)) is configured to receive the client-side global navigation satellite system output raw data signal (R5(T1(c))) and the precise orbit and clock signal (C10(T2)) via the telecommunications network (206), and generate the difference signal (T1(c)-T2) between the client-side clock signal (T1(c)) and the time stamp signal (T2).

8. The system as described in claim 7, characterized in that, At least one server global navigation satellite system receiver is configured to also generate the server global navigation satellite system output raw data signal (R7(T2(i))) based on a precise clock signal (T2(i)), which is like an atomic clock signal and is more accurate than the client clock signal (T1(c)).

9. The system as described in claim 7 or 8, characterized in that, At least one of the client devices is further configured to generate the client clock signal (T1(c)) using a disciplined oscillator (212) based on the difference signal (T1(c)-T2) as a feedback signal.

10. The system as described in claim 8, characterized in that, The precise clock signal (T2(i)) includes information about the global navigation satellite system receiver clock and / or at least one satellite clock.

11. The system as described in claim 7 or 8, characterized in that, At least one server-side Global Navigation Satellite System (GNSS) device includes multiple globally distributed GNSS receivers (202(i)).

12. The system as described in claim 7 or 8, characterized in that, The at least one client device includes a first client device and a second client device, wherein the first client device is configured to generate a first difference signal (T1(1)-T2) between a first client clock signal (T1(1)) and the time stamp signal (T2), and the second client device is configured to generate a second difference signal (T1(c)-T2) between a second client clock signal (T1(c)) and the time stamp signal (T2), and compare the first difference signal (T1(1)-T2) with the second difference signal (T1(c)-T2).

13. A server-based global navigation satellite system device for propagating time-stamped signals (T2), characterized in that, The device includes: Multiple Global Navigation Satellite System (GNSS) receivers (202(i)), each GNSS receiver being configured to output raw data signals from at least one or more first satellite signal generation servers (R7(T2(i))); and Processor (218), said processor (218) being configured to: Based on the raw data signals (R7(T2(i))) output by multiple servers from the global navigation satellite system, a precise orbit and clock signal (C10(T2)) embedded with the time stamp signal (T2) is generated, and The precise orbit and clock signal (C10(T2)) is broadcast via the telecommunications network (206).

14. The server-side global navigation satellite system equipment as described in claim 13, characterized in that, Each Global Navigation Satellite System (GNSS) receiver is also configured to generate the server's GNSS output raw data signal (R7(T2(i))) based on a precise clock signal (T2(i)), which is similar to an atomic clock signal.

15. The server-side global navigation satellite system equipment as described in claim 14, characterized in that, The precise clock signal (T2(i)) includes information about the global navigation satellite system receiver clock and / or satellite clock.

16. The server-side global navigation satellite system equipment as described in any one of claims 13-15, characterized in that, The Global Navigation Satellite System receivers are distributed globally.

17. A client-side global navigation satellite system device for receiving a transmitted time stamp T2, characterized in that, The device includes: A Global Navigation Satellite System (GNSS) receiver (201(c)) is configured to generate a client GNSS output raw data signal (R5(T1(c))) based on a client clock signal (T1(c)) and one or more second satellite signals. A PPP processor (203(c)) is coupled to the Global Navigation Satellite System receiver (203(c)) and configured to: Receive the raw data signal (R5(T1(c))) output by the client's global navigation satellite system and the precise orbit and clock signal (C10(T2)) from the server. Extract the time stamp signal (T2) embedded in the precise track and clock signal (C10(T2)), and Generate the difference signal (T1(c)-T2) between the client clock signal (T1(c)) and the time stamp signal (T2).

18. The client-side global navigation satellite system equipment as described in claim 17, characterized in that, It also includes a disciplined oscillator (212(c)) configured to generate the client clock signal (T1(c)) based on the difference signal (T1(c)-T2) as a feedback signal.

19. The client-side global navigation satellite system equipment as described in claim 17 or 18, characterized in that, The PPP processor (203(c)) is further configured to exchange the generated difference signal (T1(c)-T2) with another client global navigation satellite system device, and to compare the generated difference signal (T1(c)-T2) with the difference signal (T1(c)-T2) generated by the other client global navigation satellite system device.

20. A method for propagating a time-stamped signal (T2) from at least one server site to at least one client site, characterized in that, The method includes: Run at least one server global navigation satellite system process (202; 202(i), i = 1, 2, ..., I), each global navigation satellite system process being configured to generate server global navigation satellite system output raw data signals (R7(T2); R7(T2(i))) based on at least one or more received first satellite signals and based on time-stamped signals (T2; T2(i)). At each server site, a server-precise point positioning PPP process (210; 210(i)) is run, the PPP process being configured to receive the server's raw data signal output from the Global Navigation Satellite System (R7(T2); R7(T2(i))) and the PPP correction signal (C(T)). PPP And generate server precise orbit and clock offset signals (T4(T)). PPP -T2); T4(T PPP -T2(i))); At the at least one server site, based on the server's precise orbit and clock timescale offset signal (T4(T)) for each server site PPP -T2); T4(T PPP -T2(i)) generates a precise track and clock signal (C8(T2)), wherein the precise track and clock signal (C8(T2)) embeds the time stamp signal (T2), and the precise track and clock signal (C8(T2)) is broadcast from the at least one server site to the at least one client site via a telecommunications network (206); At each client site, a client GNSS process (201(c)) is run, which is configured to generate a client GNSS output raw data signal (R5(T1(c))) based on a client clock signal (T1(c), c = 1, 2, ..., C) and based on one or more second satellite signals; a client process including a precise point positioning PPP process (203(c)) is run, which is configured to receive the client GNSS output raw data signal (R5(T1(c))) and the precise orbit and clock signal (C8(T2)); and generate a difference signal (T1(c)-T2) between the client clock signal (T1(c)) and the time-stamped signal (T2).

21. The method according to claim 20, characterized in that, Multiple server sites and multiple server precise orbit and clock timescale offset signals (T4(T)) PPP -T2(i))) is combined into a combined server precise track and clock timescale offset signal (T9(T PPP -T2), and the precise orbit and clock signal (C8(T2)) is based on the server precise orbit and clock timescale offset signal (T9(T)) applied to the combination. PPP -T2)) and the PPP correction signal (C(T) PPP The correction process.

22. The method according to claim 21, characterized in that, The correction process includes: determining the server's precise orbit and clock offset signal (T9(T)) based on the combination. PPP Whether the clock offset caused by -T2) exceeds a predetermined threshold; and if so, correct the clock offset so that the track and clock remain constant by one of the following: o shifts the timestamp of the combined precise orbital coordinates by a certain amount, said amount compensating for the clock offset; or o Recalculate the precise orbital coordinates at the offset clock time marker.

23. The method according to any one of claims 20-22, characterized in that, The PPP correction signal (C(T) PPP ()) is generated outside of the at least one server site.

24. The method according to any one of claims 20-22, characterized in that, The client clock signal (T1(c)) at at least one of the client sites is generated by a trained oscillator (212) based on the difference signal (T1(c)-T2; T11(c)) as a feedback signal.

25. The method according to any one of claims 20-22, characterized in that, The method includes: At the first client site, a first difference signal (T1(1)-T2; T11(1)) between the first client clock signal (T1(1)) and the time stamp signal (T2) is generated. At the second client site, a second difference signal (T1(c)-T2; T11(c)) between the second client clock signal (T1(c)) and the time stamp signal (T2) is generated. The first difference signal (T1(1)-T2; T11(1)) is compared with the second difference signal (T1(c)-T2; T11(c)).

26. The method according to any one of claims 20-22, characterized in that, At least one of the server sites includes multiple globally distributed Global Navigation Satellite System receivers.

27. A system for propagating a time-stamped signal (T2), characterized in that, The system includes: At least one server-side PPP device with precise global navigation satellite system positioning, located at at least one server site, includes: Server GNSS receivers (202; 202(i), i = 1, 2, ..., I), each server GNSS receiver is configured to generate server GNSS output raw data signals (R7(T2); R7(T2(i))) based on at least one or more received first satellite signals and based on time-stamped signals (T2; T2(i)). The server-side precise point positioning PPP processor (210; 210(i)) is configured to receive the server's global navigation satellite system output raw data signal (R7(T2); R7(T2(i))) and PPP correction signal (C(T)). PPP And generate server precise orbit and clock offset signals (T4(T)). PPP -T2); T4(T PPP -T2(i))); Processor (214), the processor (214) is configured to base its operation on the precise orbit and clock offset signal (T4(T) of each server site. PPP -T2); T4(T PPP -T2(i)) generates a precise track and clock signal (C8(T2)) at the at least one server site, wherein the precise track and clock signal (C8(T2)) embeds the time stamp signal (T2), and the precise track and clock signal (C8(T2)) is broadcast from the at least one server site to at least one client site via a telecommunications network (206); At least one client site, the client site comprising: A client-side global navigation satellite system processor (201(c)) is configured to generate a client-side global navigation satellite system output raw data signal (R5(T1(c))) based on a client clock signal (T1(c), c = 1, 2, ..., C) and based on one or more second satellite signals. The precise point positioning PPP processor 203(c) is configured to receive the raw data signal (R5(T1(c))) output by the client global navigation satellite system and the precise orbit and clock signal (C8(T2)), and generate the difference signal (T1(c)-T2) between the client clock signal (T1(c)) and the time stamp signal (T2).

28. The system according to claim 27, characterized in that, The server site includes: Combiner unit (216), the combiner unit (216) being configured to combine multiple server precise orbit and clock timescale offset signals (T4(T)) from multiple server sites PPP -T2(i))) is combined into a combined server precise track and clock timescale offset signal (T9(T PPP -T2), and a correction processor (214), the correction processor (214) being configured to base the server precise track and clock timescale offset signal (T9(T)) applied to the combination. PPP -T2)) and the PPP correction signal (C(T) PPP The calibration process on the track generates the precise track and clock signal (C8(T2)).

29. The system according to claim 28, characterized in that, The correction process includes: determining the server's precise orbit and clock offset signal (T9(T)) based on the combination. PPP Whether the clock offset caused by -T2) exceeds a predetermined threshold; and if so, correct the clock offset so that the track and clock remain constant by one of the following: o shifts the timestamp of the combined precise orbital coordinates by a certain amount, said amount compensating for the clock offset; or o Recalculate the precise orbital coordinates at the offset clock time marker.

30. The system according to any one of claims 27-29, characterized in that, The server site is configured to receive the PPP correction signal (C(T)) from outside the at least one server site. PPP )).

31. The system according to any one of claims 27-29, characterized in that, At least one of the client sites includes a trained oscillator (212(c)) configured to generate the client clock signal (T1(c)) based on the difference signal (T1(c)-T2) as a feedback signal.

32. The system according to any one of claims 27-29, characterized in that, The first client station is configured to generate a first difference signal (T1(1)-T2) between a first client clock signal (T1(1)) and the time stamp signal (T2), the second client station is configured to generate a second difference signal (T1(c)-T2) between a second client clock signal (T1(c)) and the time stamp signal (T2), and the first client station is further configured to compare the first difference signal (T1(1)-T2) with the second difference signal (T1(c)-T2).

33. The system according to any one of claims 27-29, characterized in that, At least one of the server sites includes multiple globally distributed Global Navigation Satellite System receivers.

34. A server-based global navigation satellite system device for propagating time-stamped signals (T2), characterized in that, The device includes: At least one Global Navigation Satellite System (GNSS) receiver (202; 202(i)), said GNSS receiver being configured to: The server generates the raw data signal (R7(T2); R7(T2(i))) based on at least one or more first satellite signals and based on the precise server clock signal (T2; T2(i)). At least one processor (210; 210(i)), said processor being configured to: Receive precise point positioning PPP correction signal (C(T) PPP )), Based on the server's global navigation satellite system output raw data signal (R7(T2); R7(T2(i))) and the PPP correction signal (C(T)) PPP Generate server offset signal (T4(T)) PPP -T2); T4(T PPP -T2(i))), Based on the server offset signal (T4(T) PPP -T2); T4(T PPP -T2(i)) generates a precise orbit and clock signal (C8(T2)), wherein the precise orbit and clock signal (C8(T2)) is embedded with the time stamp signal (T2), and A transceiver configured to broadcast the precise orbit and clock signal (C8(T2)) via a telecommunications network (206).

35. The server-based global navigation satellite system equipment as described in claim 34, characterized in that, The at least one processor includes: At least one PPP processor (210(i)) is configured to receive the PPP correction signal (C(T)). PPP And generate the server offset signal (T4(T)). PPP -T2); T4(T PPP -T2(i)), and The correction processor (214) is configured to perform correction based on the PPP correction signal (C(T)). PPP Additional corrections are applied to generate the precise track and clock signals.

36. The server-side global navigation satellite system equipment as described in claim 34 or 35, characterized in that, It also includes a combiner unit configured to combine multiple server offset signals (T4(T)). PPP -T2(i)).

37. The server-side global navigation satellite system equipment as described in claim 36, characterized in that, The offset signals (T4(T)) of the multiple servers are generated by the PPP processors of other server-side Global Navigation Satellite System equipment. PPP -T2(i)).

38. The server-side global navigation satellite system equipment as described in claim 34 or 35, characterized in that, This includes receivers for multiple globally distributed global navigation satellite systems.

39. The server-based global navigation satellite system equipment as described in claim 34 or 35, characterized in that, The PPP correction signal (C(T) PPP The data is generated outside the server's global navigation satellite system equipment.

40. A client-side global navigation satellite system device for receiving a propagated time scale (T2), characterized in that, The device includes: At least one Global Navigation Satellite System (GNSS) receiver (201(c)) is configured to generate a client GNSS output raw data signal (R5(T1(c))) based on a client clock signal (T1(c)) and one or more second satellite signals. A single Precision Point Positioning PPP processor (203(c)) is coupled to each Global Navigation Satellite System receiver (201(c)) and is configured to: Receive PPP-corrected precise track and clock signals (C8(T2)) with embedded time stamp signals (T2) from the server site. Generate the difference signal (T1(c)-T2) between the client clock signal (T1(c)) and the time stamp signal (T2). The difference signal (T1(c)-T2) is generated based on the original data signal (R5(T1(c))) output by the client's global navigation satellite system and the precise orbit and clock signal (C8(T2)) corrected by PPP.

41. The client-side global navigation satellite system equipment as described in claim 40, characterized in that, It also includes a disciplined oscillator (212(c)) configured to generate the client clock signal (T1(c)) based on the difference signal (T1(c)-T2) as a feedback signal.

42. At least two client devices in a plurality of client global navigation satellite system devices as described in any one of claims 40-41, characterized in that, At least one of the plurality of client devices, a PPP processor (203(c)) is further configured to: exchange the generated difference signal (T1(c)-T2) with another client global navigation satellite system device, and compare the generated difference signal (T1(c)-T2) with the difference signal (T1(c)-T2) generated by the other client global navigation satellite system device.

43. A method for propagating a time-stamped signal (T2) from at least one server site to at least one client site, characterized in that, The method includes: Run at least one server global navigation satellite system process (202; 202(i), i = 1, 2, ..., I), each global navigation satellite system process being configured to generate server global navigation satellite system output raw data signals (R7(T2); R7(T2(i))) based on at least one or more received first satellite signals and based on time-stamped signals (T2; T2(i)). At each server site, a server-precise point positioning PPP process (210; 210(i)) is run, the PPP process being configured to receive the server's raw data signal output from the Global Navigation Satellite System (R7(T2); R7(T2(i))) and the PPP correction signal (C(T)). PPP And generate server precise orbit and clock offset signals (T4(T)). PPP -T2); T4(T PPP -T2(i))); Broadcasting from the at least one server site to the at least one client site via a telecommunications network (206) based on the precise orbit and clock offset signal (T4(T) of each server) PPP -T2); T4(T PPP -T2(i)) offset signal (T9(T PPP -T2)); At each client site, a client-side GNSS process (201(c)) is run, which is configured to generate a client-side GNSS output raw data signal (R5(T1(c))) based on a client clock signal (T1(c), c = 1, 2, ..., C) and based on one or more second satellite signals; a client process including a precise point positioning PPP process (203(c)) is run, which is configured to receive the PPP correction signal (C(T1(c))). PPP The client's global navigation satellite system outputs the raw data signal (R5(T1(c))) and the offset signal (T9(T)). PPP -T2)); and generate the difference signal (T11(c)) between the client clock signal (T1(c)) and the time stamp signal (T2).

44. The method according to claim 43, characterized in that, Multiple server sites, multiple server precise orbit and clock timescale offset signals (T4 (T PPP -T2(i)) is combined into a combined server precise track and clock offset signal (T9(T PPP -T2), the combined server precise orbit and clock timescale offset signal (T9(T)). PPP -T2) is sent as the offset signal.

45. A system for propagating a time-stamped signal (T2) from at least one server site to at least one client site, characterized in that, The system includes, at the at least one server site: At least one server-side Global Navigation Satellite System (GNSS) precise point positioning PPP device, including: Server Global Navigation Satellite System (GNSS) receivers (202; 202(i), i = 1, 2, ..., I), each GNSS receiver is configured to generate server GNSS output raw data signals (R7(T2); R7(T2(i))) based on at least one or more received first satellite signals and based on time-stamped signals (T2; T2(i)). Server-side precise point positioning PPP processor (210; 210(i)), the server-side precise point positioning PPP processor being configured to receive the server's global navigation satellite system output raw data signal (R7(T2); R7(T2(i))) and PPP correction signal (C(T))). PPP The server outputs raw data signals (R7(T2); R7(T2(i))) and PPP correction signals (C(T)) based on the global navigation satellite system output of the server. PPP Generates precise orbital and clock offset signals for the server (T4(T)). PPP -T2); T4(T PPP -T2(i))); Broadcasting from the at least one server site to the at least one client site via a telecommunications network (206) based on the precise orbit and clock offset signal (T4(T) of each server) PPP -T2); T4(T PPP -T2(i)) offset signal (T9(T PPP -T2)); The system includes the following at each client site: A client-side global navigation satellite system receiver (201(c)) is configured to generate a client-side global navigation satellite system output raw data signal (R5(T1(c))) based on a client clock signal (T1(c), c = 1, 2, ..., C) and based on one or more second satellite signals. The client-side precise point positioning PPP processor (221(c)) is configured to receive the PPP correction signal (C(T)). PPP The client's global navigation satellite system outputs the raw data signal (R5(T1(c))) and the offset signal (T9(T)). PPP -T2), and generate the difference signal (T11(c)) between the client clock signal (T1(c)) and the time stamp signal (T2).

46. ​​The system according to claim 45, characterized in that, The at least one server site includes a combiner unit (224) configured to combine multiple server precision track and clock offset signals (T4(T)). PPP -T2(i))) is combined into a combined server precise track and clock timescale offset signal (T9(T PPP -T2), the combined server precise orbit and clock timescale offset signal (T9(T)). PPP -T2) is sent as the offset signal.

47. A server-based global navigation satellite system device for propagating time-stamped signals (T2), characterized in that, The device includes: At least one Global Navigation Satellite System (GNSS) receiver (202; 202(i)), said GNSS receiver being configured to: The server generates the raw data signal output by the global navigation satellite system based on at least one or more first satellite signals and based on the precise server clock signal (T2; T2(i)). At least one processor (210; 210(i)), said processor being configured to: Receive precise point positioning PPP correction signal (C(T) PPP )), Based on the server's global navigation satellite system output raw data signal (R7(T2); R7(T2(i))) and the PPP correction signal (C(T)) PPP Generate server offset signal (T4(T)) PPP -T2); T4(T PPP -T2(i))), Based on the server offset signal (T4(T) PPP -T2); T4(T PPP -T2(i)) generates a precise orbit and clock signal (C8(T2)), wherein the precise orbit and clock signal (C8(T2)) embeds the time stamp signal (T2), and Based on the server's global navigation satellite system output raw data signal (R7(T2); R7(T2(i))) and the PPP correction signal (C(T)) PPP Generates precise orbital and clock offset signals for the server (T4(T)). PPP -T2); T4(T PPP -T2(i))); Broadcasting from the at least one server site to the at least one client site via a telecommunications network (206) based on the precise orbit and clock offset signal (T4(T) of each server) PPP -T2); T4(T PPP -T2(i)) offset signal (T9(T PPP -T2).

48. The server-side global navigation satellite system equipment as described in claim 47, characterized in that, It also includes a combiner unit configured to combine multiple server offset signals (T4(T)). PPP -T2(i)).

49. The server-based global navigation satellite system equipment as described in claim 48, characterized in that, The offset signals (T4(T)) of the multiple servers are generated by the PPP processors of other server-side Global Navigation Satellite System equipment. PPP -T2(i)).

50. The server-side global navigation satellite system equipment as described in any one of claims 47-49, characterized in that, This includes receivers for multiple globally distributed global navigation satellite systems.

51. The server-side global navigation satellite system equipment as described in any one of claims 47-49, characterized in that, The PPP correction signal (C(T) PPP The data is generated outside the server's global navigation satellite system equipment.

52. A client-side global navigation satellite system device for receiving a propagated timescale (T2), characterized in that, The device includes: At least one Global Navigation Satellite System (GNSS) receiver (201(c)) is configured to generate a client GNSS output raw data signal (R5(T1(c))) based on a client clock signal (T1(c)) and one or more second satellite signals. A single Precision Point Positioning PPP processor (221(c)) is coupled to each Global Navigation Satellite System receiver (201(c)) and is configured to: Receive server precise track and clock time offset signal (T9(T2)) embedded with time stamp signal (T2) from at least one server site. PPP -T2), and receive the PPP correction signal (T PPP ); Generate the difference signal (T11(c)) between the client clock signal (T1(c)) and the time stamp signal (T2). The difference signal (T11(c)) is based on the raw data signal output by the client's global navigation satellite system (R5(T1(c))) and the server's precise orbit and clock offset signal (T9(T)). PPP -T2) and the PPP correction signal (T PPP Generated by ).

53. The client-side global navigation satellite system equipment as described in claim 47, characterized in that, The PPP processor (221(c)) is further configured to generate the received PPP correction signal (T). PPP The PPP difference signal (T3(c)) between the client clock signal (T1(c)) and the server precise orbit and clock timescale offset signal (T9(T)) is compared. PPP -T2)) to obtain the difference signal (T11(c)).

54. The client-side global navigation satellite system equipment as described in claim 47 or 48, characterized in that, It also includes a tunable oscillator (212(c)) configured to generate the client clock signal (T1(c)) based on the difference signal (T11(c)) as a feedback signal.

55. At least two client devices in a plurality of client global navigation satellite system devices as described in claim 47 or 48, characterized in that, At least one of the plurality of client devices, a PPP processor (221(c)) is further configured to: exchange the generated difference signal (T11(c)) with another client global navigation satellite system device, and compare the generated difference signal (T11(c)) with the difference signal (T11(c)) generated by the other client global navigation satellite system device.

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