A heterodyne GNSS satellite time service receiving device and time service method

Abstract

The present application relates to the field based on GNSS satellite time service, propose a heterodyne GNSS satellite time service receiving device and time service method, the receiving device includes GNSS receiving module A, GNNS receiving module B, ephemeris phase processing unit, differential filtering processing unit, local clock generation unit, processor unit ARM and input, output interface;GNSS receiving module A and GNSS receiving module B are used to obtain satellite observation;Ephemeris phase processing unit is used to process the second pulse physical signal of observation;Differential filtering processing unit is used to carry out differential operation and filtering processing between modules to the processed second pulse physical signal;Local clock generation unit completes high-precision timing function under the control of differential filtering processing unit, and outputs time-frequency signal through output port.The present application can significantly reduce the timing error of satellite signal, and output more accurate clock signal through the local clock generation unit.

Description

Technical Field

[0001] This invention relates to the field of GNSS satellite timing, specifically to a heterodyne GNSS satellite timing receiver and timing method. Background Technology

[0002] The timing accuracy of GNSS (Global Navigation Satellite System) satellites is affected by more than a dozen factors, including satellite orbit, satellite clock error, pseudorange observation noise, ionospheric and tropospheric errors, receiver clock error, and the surrounding environment. Ordinary GNSS receivers can generally achieve a timing accuracy of tens of nanoseconds.

[0003] Common-view timekeeping is a highly accurate time transfer method proposed by the U.S. National Bureau of Standards in 1980 and continuously expanded and improved by researchers both domestically and internationally. Currently, common-view timekeeping is one of the main methods for long-distance time comparison, achieving nanosecond-level accuracy. The basic principle of common-view timekeeping is that two users, A and B, located at different locations, simultaneously receive signals from satellite S, obtaining the time difference between satellite S and their local time. This time difference includes various errors from the satellite signal propagation path and the receiver. A and B obtain the time difference between their locations through real-time or post-event data exchange. In common-view timekeeping, the process of data exchange and difference calculation between the two locations can completely offset satellite clock errors, most ephemeris errors, and tropospheric and ionospheric time delay errors, greatly improving the accuracy of time comparison between the two locations. In next-generation GNSS-based common-view timekeeping systems, a single reference station is typically configured with multiple reference terminals. These reference terminals simultaneously observe the GNSS satellite constellation, and the deviation between the local time and the satellite clock, i.e., the satellite station clock error, is obtained by calculating pseudorange. Due to differences in observation location and angle, different reference terminals observe different satellites and their numbers at the same time. Therefore, satellite clock bias typically has the following characteristics: ① The observation data of each reference terminal usually includes satellite clock bias data from multiple satellites; ② The clock bias observation data of each satellite inevitably contains outliers and missing values, and the location and length of the missing values ​​are random; ③ Only the clock bias of the same satellite from multiple reference terminal observation data can be used for data fusion processing.

[0004] Using satellite common-view (CV) technology, time synchronization and remote time-frequency comparison accuracy better than 10ns can be achieved. CV generally relies on a national-level time and frequency center or similar device (base station) to provide reference time and frequency signals, and requires the establishment of dedicated data channels between common-view sites (such as the base station and common-view slave stations) for exchanging common-view data. Furthermore, the common-view method has limitations on the distance between the base station and the common-view slave station; the baseline length generally cannot exceed 3000km.

[0005] Precise point positioning (PPP) technology can achieve nanosecond-level time synchronization. However, this method requires the support of a PPP service platform. The platform collects and processes GNSS observation data, obtains correction values ​​such as clock bias for each satellite, and transmits them to the PPP receiver. Naturally, this method also requires the establishment of a data link between the PPP service platform and the receiver to transmit correction data.

[0006] High-precision time synchronization can also be achieved using satellite two-way technology. This method requires the support of communication satellites and channels, and the satellite antenna is relatively large compared to the GNSS antenna.

[0007] In summary, the deployment costs of satellite two-way communication, satellite common-view (CV) technology, and precise point positioning (PPP) technology are currently relatively high, which limits their widespread application to some extent. Summary of the Invention

[0008] The purpose of this invention is to solve the above-mentioned problems by proposing a heterodyne GNSS satellite timing receiver. This device utilizes timing signals output from two independent short-baseline GNSS signal receiving units. By selecting ephemeris data and corresponding timing signals, it further performs inter-satellite differential processing and inter-module differential processing of the GNSS timing signal receiving module. It also performs hybrid differential processing between the satellite and the receiving module, significantly reducing satellite signal timing errors, obtaining accurate time and frequency signals, and calibrating the local clock generation unit. The clock signal output by the local clock generation unit is more accurate than that of a single GNSS receiving module.

[0009] The technical solution adopted is as follows:

[0010] A heterodyne GNSS satellite timing receiver, characterized in that it includes: a GNSS receiving module A, a GNSS receiving module B, an ephemeris phase detection processing unit, a differential filtering processing unit, a local clock generation unit, a processor unit ARM, and input and output interfaces.

[0011] The GNSS receiving module A and GNSS receiving module B are used to acquire satellite observations; the ephemeris phase detection processing unit is used to process the observation signals; the differential filtering processing unit is used to perform inter-module differential operations and filtering on the processed satellite observation signals; the local clock generation unit performs timing functions under the control of the differential filtering processing unit and outputs time and frequency signals through the output port; the processor unit ARM manages and controls the operation of the heterodyne GNSS satellite timing receiver to complete the designed functions.

[0012] Furthermore, the observations include a second pulse physical signal and an ephemeris data signal, wherein the ephemeris data includes a time message data signal.

[0013] Furthermore, the satellite observation signal also includes the signal expansion unit, which is used to expand the signal output by the local clock generation unit into multiple time-frequency signals.

[0014] Furthermore, the receiving modules A and B can be implemented using chips or receivers, and the ephemeris phase detection processing unit, differential filtering processing unit, and local clock generation unit can be implemented using programmable logic gate devices (FPGAs) and digital frequency synthesizers (DDSs).

[0015] A timing method for a heterodyne GNSS satellite timing receiver, the specific steps of which are as follows:

[0016] S1. Satellite observations are acquired by the GNSS timing receiver modules A and B respectively, including second pulse physical signals and ephemeris data signals;

[0017] S2. The ephemeris phase detection processing unit receives and processes the two second pulse physical signals output by the GNSS timing receiver modules A and B, and at the same time marks the corresponding satellite numbers as I and J according to the acquired ephemeris data and stores them temporarily.

[0018] S3. Perform inter-module differential processing on the second pulse physical signal processed in step S2 using the differential and filtering processing unit:

[0019] S31. The GNSS timing receiver modules A and B simultaneously acquire the second pulse physical signal of the same satellite I or J and perform parallel differential processing.

[0020] S32. The GNSS timing receiver module A or B simultaneously receives the second pulse physical signals of satellites I and J and performs differential processing.

[0021] One or both of the two differential processing methods in steps S31 and S32 above can be selected;

[0022] S4. The second pulse physical signal after differential processing is used as the reference signal of the local clock generation unit, and the operation of the high-stability voltage controlled oscillator of the local clock generation unit is controlled by the differential and filtering processing unit. The output signal is the time and frequency signal obtained after processing.

[0023] Furthermore, the ephemeris data includes time message data signals.

[0024] Furthermore, the output signal can be expanded into multiple time-frequency signals.

[0025] Furthermore, step S3 may also include: S33 adopting hybrid differential processing between satellites and between modules simultaneously: the GNSS timing receiver modules A and B respectively receive the observation signals of satellites I and J and perform differential processing, and any one of the three differential processing methods in steps S31, S32 and S33, or a combination of two or three.

[0026] The beneficial effects of this invention compared to the prior art are as follows:

[0027] 1. This invention does not require the establishment of a CV reference station or a dedicated PPP service platform as commonly used high-precision time synchronization or time transmission methods. It can obtain high-precision time and frequency signals relatively independently with GNSS support. It does not require the configuration of long-distance data links as is usually the case and is not limited by the baseline length.

[0028] 2. This invention can reduce satellite-related timing errors, including satellite clock errors, ephemeris errors, antenna phase center errors, relativistic effects, etc., as well as timing signal propagation errors, including ionospheric, tropospheric, multipath and receiver errors.

[0029] 3. The cost of a single machine required to implement this invention is much lower than that of CV or PPP, which is conducive to its widespread application. Attached Figure Description

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the heterodyne GNSS satellite timing receiver of the present invention.

[0032] Figure 2 A schematic diagram of two receiving modules A and B of the present invention simultaneously receiving the same satellite timing signal.

[0033] Figure 3 A schematic diagram of a receiving module of the present invention simultaneously receiving timing signals from two satellites.

[0034] Figure 4 A schematic diagram of the two receiving modules of this invention simultaneously receiving timing signals from two satellites.

[0035] The annotations in the attached figures are explained as follows:

[0036] 1-GNSS receiver module A, 2-GNSS receiver module B, 3-Ephemeris phase detection processing unit, 4-Differential filtering processing unit, 5-Local clock generation unit, 6-Power supply, 7-Satellite I, 8-Satellite J. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] The present invention will now be described in further detail with reference to the accompanying drawings:

[0039] like Figure 1 As shown, a heterodyne GNSS satellite timing receiver includes: a GNSS receiving module A1, a GNSS receiving module B2, an ephemeris phase detection processing unit 3, a differential filtering processing unit 4, a local clock generation unit 5, a microprocessor ARM, and input / output interfaces (not shown); it also includes a power supply 6 for supplying power to modules A and B and each unit, and includes an antenna and a feed line (…). Figure 1 (Not shown); the receiving module can be implemented using a chip or a receiver.

[0040] The GNSS receiving modules A1 and B2 are used to acquire satellite observations; the ephemeris phase detection processing unit 3 is used to process the satellite observation signals; the differential filtering processing unit 4 is used to perform differential operations between modules on the processed satellite observation signals; and the local clock generation unit 5 completes high-precision timing functions under the control of the differential filtering processing unit and outputs time and frequency signals through the output port.

[0041] The observations include a second pulse physical signal and an ephemeris data signal, the ephemeris data including a time message data signal.

[0042] The satellite observation signal also includes the signal expansion unit, which is used to expand the signal output by the local clock generation unit into multiple time-frequency signals.

[0043] The timing method based on the above-mentioned heterodyne GNSS satellite timing receiver device includes the following specific steps:

[0044] S1. Satellite observations are acquired by GNSS timing receiver modules A and B respectively. The satellite observations include second pulse physical signals and ephemeris data signals. The ephemeris data includes time message data signals.

[0045] S2. The ephemeris phase detection processing unit receives and processes the second pulse physical signals output by the GNSS timing receiver modules A and B, and at the same time marks the corresponding satellite numbers as I and J according to the acquired ephemeris data and temporarily stores them.

[0046] S3. Perform inter-module differential processing on the second pulse physical signal through the differential and filtering processing unit:

[0047] S31. The GNSS timing receiver modules A and B simultaneously acquire the second pulse physical signals of the same satellite I or J, which undergo parallel differential processing, such as... Figure 2 As shown, this is used to eliminate clock bias in the receiving module;

[0048] S32. The GNSS timing receiver module A or B simultaneously receives the second pulse physical signals of satellites I and J and performs differential processing, such as... Figure 3 As shown, this is used to eliminate satellite clock errors;

[0049] S33. Simultaneous hybrid differential processing is adopted between satellites and between modules, such as... Figure 4 As shown;

[0050] In steps S31, S32, and S33, any one of the three differential processing methods can be selected, or a combination of two or three methods can be used.

[0051] S4. The differentially processed second pulse physical signal serves as the reference signal for the local clock generation unit. The differential and filtering processing unit controls the operation of the high-stability voltage-controlled oscillator of the local clock generation unit, outputting the processed time and frequency signals, i.e., the time-frequency signal. The output signal can be expanded into multiple time-frequency signals.

[0052] In general, differential clocking refers to a technique in clock circuit design: converting an unbalanced input signal to a balanced (opposite phase) signal, followed by differential processing, which can effectively suppress common-mode noise. The heterodyne satellite timing receiver system described in this invention can provide high-precision time and frequency signals. Utilizing timing signals output from two independent short-baseline GNSS signal receiving units, and by selecting ephemeris data and corresponding timing signals, further differential processing is performed between GNSS satellites and between GNSS timing signal receiving modules. It can also perform hybrid differential processing between satellites and receiving modules, significantly reducing satellite signal timing errors, obtaining accurate time and frequency signals, and taming the local clock generation unit. In this embodiment, the video signal output by the local clock generation unit, which is more accurate than that of a single GNSS receiving module, is a 1pps, 10MHz, TOD signal. The obtained clock signal is a high-precision, low-cost time and frequency signal with a time deviation of <3ns (relative to UTC) and frequency stability reaching E-14 daily stability level.

[0053] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A heterodyne GNSS satellite timing receiver, characterized in that, include: GNSS receiver module A, GNSS receiver module B, ephemeris phase detection processing unit, differential filtering processing unit, local clock generation unit, processor unit ARM and input / output interfaces; The GNSS receiving module A and GNSS receiving module B are used to acquire satellite observation signals; the ephemeris phase detection processing unit is used to process the satellite observation signals; the differential filtering processing unit is used to perform inter-module differential operations and filtering on the processed satellite observation signals; the local clock generation unit completes the timing function under the control of the differential filtering processing unit and outputs the time and frequency signal through the output port; the processor unit ARM manages and controls the operation of the heterodyne GNSS satellite timing receiver to complete the designed functions.

2. The heterodyne GNSS satellite timing receiver according to claim 1, characterized in that, The satellite observation signals include second pulse physical signals and ephemeris data signals, and the ephemeris data includes time message data signals.

3. A heterodyne GNSS satellite timing receiver according to claim 2, characterized in that, The satellite observation signal also includes a signal expansion unit, which is used to expand the signal output by the local clock generation unit into multiple time-frequency signals.

4. A heterodyne GNSS satellite timing receiver according to claim 3, characterized in that, The GNSS receiving modules A and B are implemented using chips or receivers, and the ephemeris phase detection processing unit, differential filtering processing unit, and local clock generation unit are implemented using programmable logic gate devices (FPGA) and digital frequency synthesizers (DDS).

5. A timing method for a heterodyne GNSS satellite timing receiver according to any one of claims 1-4, characterized in that, The specific steps are as follows: S1. Satellite observation signals are acquired by the GNSS receiving modules A and B respectively. The satellite observation signals include second pulse physical signals and ephemeris data signals. S2. The ephemeris phase detection processing unit receives and processes the two second pulse physical signals output by the GNSS receiving modules A and B, and at the same time, it temporarily stores the satellite numbers I and J corresponding to the collected ephemeris data signals. S3. Perform inter-module differential processing on the second pulse physical signal processed in step S2 using the differential and filtering processing unit: S31. The GNSS receiving modules A and B simultaneously acquire the second pulse physical signal of the same satellite I or J and perform parallel differential processing. S32. The GNSS receiving module A or B simultaneously receives the second pulse physical signals of satellites I and J and performs differential processing. Choose one or both of the two differential processing methods in steps S31 and S32 above; S4. The second pulse physical signal after differential processing is used as the reference signal of the local clock generation unit, and the operation of the high-stability voltage controlled oscillator of the local clock generation unit is controlled by the differential filtering processing unit. The output signal is the time and frequency signal obtained after processing.

6. The time synchronization method according to claim 5, characterized in that, Step S3 further includes: S33 adopts simultaneous hybrid differential processing between satellites and between modules: the GNSS receiving modules A and B respectively receive the observation signals of satellites I and J and perform differential processing, and any one of the three differential processing methods in steps S31, S32 and S33, or a combination of two or three.

Images