A high-orbit satellite dual-frequency weighted fusion frequency-locked loop GNSS tracking and receiving system and method

Abstract

A high-orbit satellite dual-frequency weighted fusion frequency-locked loop GNSS tracking and receiving system and method utilizes a dual-frequency GNSS antenna to simultaneously receive dual-frequency GNSS signals; the dual-frequency GNSS signals are low-noise amplified and sequentially processed through a downconverter, an analog-to-digital converter, a mixer, a correlator, and a frequency discriminator. The signal-to-noise ratio (SNR) of the two signals is calculated using a SNR estimation module to determine whether the SNRs of the two signals exceed a set threshold. When only one of the two signals has a SNR exceeding the set threshold, the frequency error and code phase observations of the signal exceeding the set threshold are selected to drive the frequency-locked loop and the code loop, respectively. When both signal-to-noise ratios of the two signals exceed the set threshold, the frequency error and code phase observations are fused, and the fused frequency error and code observation fusion error are used to drive the frequency-locked loop and the code loop, respectively. The carrier frequency control word is obtained and sent to the carrier NCO, and the code frequency control word is obtained and sent to the code NCO. The present invention improves the availability of GNSS receiving systems in high orbits.

Description

Technical Field

[0001] The present invention belongs to the field of satellite-borne GNSS navigation receivers and relates to a high-sensitivity GNSS receiving system and method for high-orbit satellites. Background Art

[0002] High-orbit spacecraft, such as those in geostationary orbit, inclined geosynchronous orbit, and highly eccentric orbits, as well as lunar deep space probes, play an important role in satellite communications, early warning and surveillance, and meteorological observation. Currently, high-orbit satellites rely primarily on ground-based measurement and control (T&C) for orbit determination. As the number and variety of high-orbit spacecraft continue to increase, the demand for high-precision orbit determination for high-orbit Earth observation payloads is increasing, putting increasing strain on traditional ground-based T&C systems.

[0003] The Global Navigation Satellite System (GNSS) has the characteristics of all-day, all-weather and global coverage, and has been widely used in low-orbit spacecraft. Using GNSS navigation in high-orbit space can effectively alleviate the pressure of ground measurement and control and realize autonomous real-time navigation.

[0004] Compared to traditional GNSS navigation, high-Earth orbit GNSS receivers need to receive GNSS sidelobe leakage signals, whose power is approximately 20dB lower than the mainlobe signal and whose spatial distribution of signal power is less continuous. The greater distance between GEO users and the GNSS constellation further reduces the received power. Furthermore, referring to the GPS signal transmit antenna pattern characteristics published by Lockheed Martin, GNSS signal sidelobes are discretely distributed across different regions in space.

[0005] To improve the GNSS navigation performance of high-orbit satellites, the traditional solution is to develop high-sensitivity GNSS signal processing algorithms that can process more GNSS missed signals and improve system availability by improving sensitivity.

[0006] Wang Meng, Shan Tao, Wang Dun. Development of GNSS Technology for High-Earth Orbit Spacecraft. Acta Geodaetica et Cartographica Sinica, 2020, 49(9): 1158-1167. DOI: 10.11947 / j.AGCS.2020.20200170. This paper introduces the development of high-orbit GNSS receivers and mentions that "in terms of high-sensitivity signal tracking technology, the existing main technical means mainly rely on traditional phase-locked loops (PLLs) and frequency-locked loops (FLLs) to track weak signals."

[0007] HARSHA PBS, RATNAM D V. Implementation of advanced carrier tracking algorithm using adaptive-extended Kalman filter for GNSS receivers[J]. IEEE Geoscience and Remote Sensing Letters, 2016, 13(9): 1280-1284] introduced the use of Kalman filter (KF) high-sensitivity loop processing to establish the state and measurement equation model of carrier Doppler phase, frequency shift and frequency change rate to achieve weak signal carrier tracking.

[0008] HENKEL P, GIGER K, GUNTHER C. Multifrequency, multisatellite vectorphase-locked loop for robust carrier tracking[J]. IEEE Journal of SelectedTopics in Signal Processing, 2009, 3(4): 674-681 The vector tracking loop technology is used to jointly track the carrier phase of all satellites on multiple frequencies, which can further improve the tracking sensitivity.

[0009] CAPUANO V, BLUNT P, BOTTERON C, et al. Orbital filter aiding of a high sensitivity GPS receiver for lunar missions[C] / / Proceedings of 2016International Technical Meeting of The Institute of Navigation. Monterey, CA:[sn], 2016. In order to improve the navigation performance, the high orbit determination filter is realized by using the dynamic model and GNSS observations, and the orbit filtering results are used to assist the tracking loop to improve the sensitivity.

[0010] The aforementioned methods all aim to improve receiver sensitivity, thereby enhancing signal visibility and improving system availability. However, these methods fail to enhance system availability through the fusion processing of multi-frequency signals transmitted by GNSS. This is particularly true when the receiver operates within the GNSS system's sidelobe coverage area. Due to the uncorrelated coverage and random intensity distribution of the multi-frequency signals in the sidelobe coverage area, the receiving system fails to fully exploit the GNSS signal characteristics to improve continuity. Summary of the Invention

[0011] The technical problem addressed by this invention is to overcome the shortcomings of existing technologies and provide a high-orbit satellite dual-frequency weighted fusion high-sensitivity GNSS tracking and reception system and method. This system leverages the multi-frequency characteristics of GNSS signals, the continuous and consistent mainlobe energy distribution across multiple frequencies, and the inconsistency and randomness of sidelobe signals across multiple frequencies. The system fuses the dual-frequency signals at the receiver signal processing level, and improves upon the traditional frequency-locked / phase-locked structure during the signal fusion process. Compared to a phase-locked loop (PLL), a frequency-locked loop (FLL) offers greater dynamic adaptability and sensitivity. Combined with dual-frequency fusion processing, this system improves sensitivity by over 3dB.

[0012] The technical solution of the present invention is: a high-orbit satellite dual-frequency weighted fusion frequency-locked loop GNSS tracking and receiving system, including a dual-frequency GNSS antenna, a dual-frequency LNA, a frequency f1 signal processing channel and a frequency f2 signal processing channel, a signal-to-noise ratio estimation module, a data fusion selection module, a frequency-locked loop, a code loop, a carrier NCO, and a code NCO, wherein:

[0013] Dual-frequency GNSS antenna, used to simultaneously receive dual-frequency GNSS signals, the two frequencies are f1 and f2;

[0014] a dual-frequency LNA for low-noise amplification of the dual-frequency GNSS signal;

[0015] The signal processing channel of frequency f1 and the signal processing channel of frequency f2 have the same structure, and both include a down-converter, an analog-to-digital converter, a mixer, a correlator and a frequency discriminator connected in sequence;

[0016] The signal-to-noise ratio estimation module receives the signals output by two correlators at the same time and right and Perform signal-to-noise ratio estimation to obtain the noise estimation value of the dual-frequency signal Send to data fusion selection module;

[0017] The data fusion selection module receives the frequency error of the f1 branch from the two frequency discriminators at the same time. and f2 branch frequency error Code phase observation And the noise estimation value input to the signal-to-noise ratio estimation module Determine whether the signal-to-noise ratio of the two signals exceeds the set threshold. When only one of the two signals has a signal-to-noise ratio that exceeds the set threshold, select the frequency error and code phase observation value of the signal that exceeds the set threshold to drive the frequency lock loop and the code loop respectively, obtain the carrier frequency control word and send it to the carrier NCO, and obtain the code frequency control word and send it to the code NCO; when the signal-to-noise ratio of both signals exceeds the set threshold, fuse the frequency error and code phase observation value, and use the fused frequency error and code observation fusion error to drive the frequency lock loop and the code loop respectively, obtain the carrier frequency control word and send it to the carrier NCO, and obtain the code frequency control word and send it to the code NCO;

[0018] The carrier NCO generates a local carrier according to the carrier frequency control word and sends it to two mixers at the same time. The code NCO generates a local regenerative spread spectrum code according to the code frequency control word and sends it to two correlators at the same time.

[0019] Furthermore, the fusion of the frequency error and code phase observation values ​​is specifically as follows:

[0020] Fusion frequency error

[0021] Code observation fusion error

[0022] Furthermore, the signals output by the two correlators are and Specifically:

[0023]

[0024] where a i represents the amplitude of the i-th received signal, f represents the intermediate frequency, c i represents the spreading code of the i-th received signal, k represents the time, T coh represents the coherent integration time, and n f1 represents the residual carrier of the f1 branch signal and the noise of the f1 branch signal, and n f2 Indicates the residual carrier of the f2 branch signal and the noise of the f2 branch signal. When the loop is stable

[0025] Furthermore, the frequency error of the f1 branch of the two frequency discriminators input is and f2 branch frequency error Specifically:

[0026]

[0027] represents the frequency difference f1, represents the observation noise at frequency f1, represents the frequency difference f2, represents the observation noise at frequency f2.

[0028] The present invention also provides a high-orbit satellite dual-frequency weighted fusion frequency-locked loop GNSS tracking and receiving method,

[0029] Use a dual-frequency GNSS antenna to simultaneously receive dual-frequency GNSS signals, with the two frequencies being f1 and f2.

[0030] performing low-noise amplification on the dual-frequency GNSS signal;

[0031] The frequency f1 signal and the frequency f2 signal are processed in sequence by a down-converter, an analog-to-digital converter, a mixer, a correlator, and a frequency discriminator;

[0032] The output signals of the two correlators and Perform signal-to-noise ratio estimation to obtain the noise estimation value of the dual-frequency signal

[0033] According to the frequency error of the f1 branch output by the two frequency discriminators and f2 branch frequency error Code phase observation and the noise estimate Determine whether the signal-to-noise ratio of the two signals exceeds the set threshold. When only one of the two signals has a signal-to-noise ratio that exceeds the set threshold, select the frequency error and code phase observation value of the signal that exceeds the set threshold to drive the frequency lock loop and the code loop respectively, obtain the carrier frequency control word and send it to the carrier NCO, and obtain the code frequency control word and send it to the code NCO; when the signal-to-noise ratio of both signals exceeds the set threshold, fuse the frequency error and code phase observation value, and use the fused frequency error and code observation fusion error to drive the frequency lock loop and the code loop respectively, obtain the carrier frequency control word and send it to the carrier NCO, and obtain the code frequency control word and send it to the code NCO;

[0034] The carrier NCO generates a local carrier according to the carrier frequency control word and sends it to two mixers at the same time. The code NCO generates a local regenerative spread spectrum code according to the code frequency control word and sends it to two correlators at the same time.

[0035] Furthermore, the fusion of the frequency error and code phase observation values ​​is specifically as follows:

[0036] Fusion frequency error

[0037] Code observation fusion error

[0038] Furthermore, the signals output by the two correlators are and Specifically:

[0039]

[0040] where a i represents the amplitude of the i-th received signal, f represents the intermediate frequency, c i represents the spreading code of the i-th received signal, k represents the time, T coh represents the coherent integration time, and n f1 represents the residual carrier of the f1 branch signal and the noise of the f1 branch signal, and n f2 Indicates the residual carrier of the f2 branch signal and the noise of the f2 branch signal. When the loop is stable

[0041] Furthermore, the frequency error of the f1 branch output by the two frequency discriminators is and f2 branch frequency error Specifically:

[0042]

[0043] represents the f1 frequency error, represents the observation noise at frequency f1, represents the f2 frequency error, represents the observation noise at frequency f2.

[0044] The advantages of the present invention compared with the prior art are:

[0045] (1) The present invention improves the way traditional high-orbit GNSS receivers process multi-frequency signals, making full use of the characteristics of GNSS transmission signals being optimized for the Earth and its surrounding 3000km range. Under high-orbit conditions, the transmission pattern of GNSS signals at different frequencies is inconsistent and discontinuous. In different receiving areas, the type and power of received signals vary greatly. The dual-frequency signals are processed by a dual-frequency receiver, and the dual-frequency observations are fused according to the signal-to-noise ratio to improve the signal-to-noise ratio of the frequency discrimination observations, thereby expanding the visibility of the signals and improving the availability of the GNSS receiving system in high orbits.

[0046] (2) The present invention utilizes the characteristic that dual-frequency signals have no correlation in carrier phase but strong correlation in carrier frequency to weight the fusion signal and only acts on the frequency-locked loop. Signal tracking is achieved through the frequency-locked loop. Compared with the phase-locked loop, the frequency-locked loop has higher dynamic adaptability and sensitivity characteristics.

[0047] (3) The present invention utilizes the characteristic that the code phase of multi-frequency signals is consistent under vacuum conditions to eliminate signals that have passed through the atmosphere twice, and implements code tracking through a multi-frequency fusion code loop. Since the code loop has good weak signal adaptability, the receiver's code tracking capability is further improved;

[0048] (4) Under the condition of dual-frequency fusion processing, the present invention achieves seamless switching of dual-path signals, thereby improving system continuity. At the same time, loop fusion is performed based on the frequency-locked loop, thereby improving system sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a schematic diagram of the dual-frequency fusion GNSS receiving system of the present invention. DETAILED DESCRIPTION

[0050] As we all know, the transmitting antennas of all GNSS systems (GPS, Galileo, Glonass, BDS, etc.) are designed with array antennas. The gain pattern is optimized for ground users. The main lobe covers the earth and users within 3000km around the earth. The signal main lobe is within ±22 degrees of the antenna beam angle. The signal in the main lobe is stable and continuous. The gain of multi-frequency signals in the main lobe coverage area is guaranteed by the ICD file. Traditional receivers generally use dual-frequency signals to correct the influence of the ionosphere on the signal transmission delay. The antenna outside the main lobe beam (leakage signal) does not optimize the signal gain, and the power of the leakage signal at different frequencies and the transmission direction corresponding to the leakage power are uncertain. The present invention makes full use of the inconsistency and discontinuity of the distribution of multi-frequency GNSS leakage signals in the high-orbit service area. Through dual-frequency fusion reception, the performance of high-orbit GNSS receivers is improved, and it can be widely used in high-orbit GNSS receivers.

[0051] The main idea of ​​the present invention is to simultaneously receive dual-frequency GNSS signals through a single antenna, perform independent down-conversion and AD quantization and related processing on the dual-frequency signals at the signal processing end, and fuse the discriminator output errors into the frequency-locked loop and code loop to achieve spatial complementarity of the two frequency point signals and improve the signal-to-noise ratio, thereby improving the continuity of the system.

[0052] like Figure 1 The figure shows a block diagram of the composition principle of the GNSS tracking and receiving system of the present invention, which includes a dual-frequency GNSS antenna, a dual-frequency LNA (a wideband LNA can meet dual-band use), a dual-frequency channel section (including channel f1, channel f2, analog-to-digital converter f1, analog-to-digital converter f2), a dual-channel mixer (mixer f1, mixer f2), a dual-channel correlator (correlator f1, correlator f2), a dual-channel discriminator (discriminator f1, discriminator f2), a signal-to-noise ratio estimation module, a data fusion selection module, a frequency-locked loop, a code loop, a carrier NCO, and a code NCO. The purpose of the dual-frequency observation of the present invention is to expand the signal available range and improve the loop signal-to-noise ratio.

[0053] The dual-frequency output GNSS antenna receives dual-frequency GNSS signals simultaneously (assuming the two frequencies are f1 and f2). For the f1 branch signal, it is sequentially amplified by the dual-frequency LNA for low noise, down-converted by channel f1, and converted by analog-to-digital converter f1 to obtain a digital intermediate frequency signal s. if1 (k) = a if1 cos(2πf1k)c i (k) reaches mixer f1. Similarly, for the signal of branch f2, it passes through the dual-band LNA (shared with branch f1) for low-noise amplification, channel f2 for down-conversion operation, and analog-to-digital converter f2 for analog-to-digital conversion to obtain the digital intermediate frequency signal s if2 (k) = a if2 cos(2πf2k)c i (k) arrives at mixer f2. Among them, parameter a i represents the amplitude of the i-th received signal, f represents the intermediate frequency, c i represents the spreading code of the i-th received signal, k represents the time, and f1 and f2 correspond to different frequency points of the GNSS signal.

[0054] In the mixer f1, the f1 branch signal and the local carrier generated by the carrier NCO are mixed to obtain the 0 intermediate frequency signal and sent to the correlator f1. In the correlator f1, the f1 branch 0 intermediate frequency signal and the local regenerated spread spectrum code of the code NCO are correlated to obtain the IQ correlation value. At the same time, it is sent to the frequency discriminator f1 and the signal-to-noise ratio estimation module. After the frequency discriminator f1 discriminates the input signal, the frequency error of the f1 branch is obtained. Similarly, in mixer f2, the f2 branch signal is mixed with the local carrier generated by the carrier NCO to obtain a 0 intermediate frequency signal and send it to the correlator f2. In correlator f2, the f2 branch 0 intermediate frequency signal and the local regenerated spread spectrum code of the code NCO are correlated to obtain the IQ correlation value. At the same time, it is sent to the frequency discriminator f2 and the signal-to-noise ratio estimation module. After the frequency discriminator f2 discriminates the input signal, the frequency error of the f2 branch is obtained. Send to the data fusion selection module.

[0055] in T coh represents the coherent integration time, and n f1 represents the residual carrier of the f1 branch signal and the noise of the f1 branch signal, and n f2 Indicates the residual carrier of the f2 branch signal and the noise of the f2 branch signal.

[0056] When the loop is stable

[0057]

[0058] represents the frequency difference f1, represents the observation noise at frequency f1, represents the frequency difference f2, represents the observation noise at frequency f2.

[0059] In the signal-to-noise ratio estimation module, the two input signals and Perform signal-to-noise ratio estimation to obtain the noise estimation value of the dual-frequency signal Send it to the data fusion selection module (the signal ratio obtained by amplitude estimation is positively correlated with the frequency estimation error).

[0060] In the data fusion selection module, the observation quantity is introduced into the loop according to the noise estimation value fusion judgment to achieve seamless switching and obtain better than and The fusion frequency error

[0061]

[0062] The principle of the above formula is:

[0063] Assume that the measurement results of the two correlators f2 and f2 are Z0 and Z1 respectively, and the corresponding observation noise standard deviations are σ0 and σ1. The purpose of fusion is to obtain the optimal observation value of Z (maximum signal-to-noise ratio) through the linear combination of the two observations. Suppose the estimated signal is

[0064] The linear combination of two sets of observations can be expressed as:

[0065]

[0066] The observation variance is (two independent observations)

[0067]

[0068] Taking the derivative of the variance with respect to k and equating it to 0:

[0069]

[0070] Can seek The optimal fusion observation is obtained.

[0071] so

[0072]

[0073] At the same time, in the data fusion selection module, the code phase error is obtained according to the correlation value output by the correlator, and the dual-frequency code loop error fusion calculation is performed.

[0074]

[0075] where f 1code ,f 2code is the code frequency of dual-frequency modulation, is the dual-frequency code observation noise, and its energy ratio is The energy ratio is consistent with They represent the code phase observation output by correlator f1, the code phase difference of f1, the code phase observation of f2, and the code phase difference of f2 respectively.

[0076] The optimal code error estimate is obtained using the same processing method as the carrier

[0077]

[0078] In the frequency locked loop, the fused frequency error is obtained The corresponding carrier NCO frequency control word is obtained through the loop filter and sent to the carrier NCO.

[0079] In the code loop, the obtained code loop fusion error is used The corresponding code frequency control word is obtained through the loop filter and sent to the code NCO.

[0080] The implementation of the code loop filter, code NCO, carrier loop filter and carrier NCO remains consistent with that of a traditional receiver.

[0081] By continuously updating the frequency control word, the tracking loop is closed and the loop is closed.

[0082] In the fusion process, the influence of the signal-to-noise ratio estimation of the two branches on the system stability is considered. When the signal-to-noise ratio estimation is low ( The threshold can be adjusted according to different signal types), then the observation quantity of this path is not introduced into the data fusion algorithm, and the identification error of the branch with high signal-to-noise ratio is directly used to drive the loop.

[0083] Due to the fusion of dual-frequency signals, this receiver only has one set of fused pseudorange outputs and does not have the dual-frequency ionospheric correction capability. Since 99% of the signals of the high-orbit receiver do not pass through the ionosphere, the observations that pass through the ionosphere are eliminated during the signal processing process, so the fused pseudorange observations do not affect the system navigation performance.

[0084] The GNSS receiver structure involved in the present invention can be widely used in high-orbit GNSS receivers.

[0085] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A high-orbit satellite dual-frequency weighted fusion frequency-locked loop GNSS tracking and receiving system, characterized by: It includes a dual-frequency GNSS antenna, a dual-frequency LNA, a frequency f1 signal processing channel, a frequency f2 signal processing channel, a signal-to-noise ratio estimation module, a data fusion selection module, a frequency-locked loop, a code loop, a carrier NCO, and a code NCO, among which: Dual-frequency GNSS antenna, used to simultaneously receive dual-frequency GNSS signals, the two frequencies are f1 and f2; a dual-frequency LNA for low-noise amplification of the dual-frequency GNSS signal; The signal processing channel of frequency f1 and the signal processing channel of frequency f2 have the same structure, and both include a down-converter, an analog-to-digital converter, a mixer, a correlator and a frequency discriminator connected in sequence; The signal-to-noise ratio estimation module receives the signals output by two correlators at the same time and right and Perform signal-to-noise ratio estimation to obtain the noise estimation value of the dual-frequency signal Send to data fusion selection module; The data fusion selection module receives the frequency error of the f1 branch from the two frequency discriminators at the same time. and f2 branch frequency error Code phase observation And the noise estimation value input to the signal-to-noise ratio estimation module Determine whether the signal-to-noise ratio of the two signals exceeds the set threshold. When only one of the two signals has a signal-to-noise ratio that exceeds the set threshold, select the frequency error and code phase observation value of the signal that exceeds the set threshold to drive the frequency lock loop and the code loop respectively, obtain the carrier frequency control word and send it to the carrier NCO, and obtain the code frequency control word and send it to the code NCO; when the signal-to-noise ratio of both signals exceeds the set threshold, fuse the frequency error and code phase observation value, and use the fused frequency error and code observation fusion error to drive the frequency lock loop and the code loop respectively, obtain the carrier frequency control word and send it to the carrier NCO, and obtain the code frequency control word and send it to the code NCO; The carrier NCO generates a local carrier according to the carrier frequency control word and sends it to two mixers at the same time. The code NCO generates a local regenerative spread spectrum code according to the code frequency control word and sends it to two correlators at the same time. The signals output by the two correlators are and Specifically: where a i represents the amplitude of the i-th received signal, f represents the intermediate frequency, c i represents the spreading code of the i-th received signal, k represents the time, T coh represents the coherent integration time, and n f1 represents the residual carrier of the f1 branch signal and the noise of the f1 branch signal, and n f2 Indicates the residual carrier of the f2 branch signal and the noise of the f2 branch signal. When the loop is stable 2. The high-orbit satellite dual-frequency weighted fusion frequency-locked loop GNSS tracking and receiving system according to claim 1, characterized in that: The fusion of frequency error and code phase observation values ​​is specifically as follows: Fusion frequency error Code observation fusion error 3. The high-orbit satellite dual-frequency weighted fusion frequency-locked loop GNSS tracking and receiving system according to claim 2, characterized in that: The frequency error of the f1 branch of the two frequency discriminators input is and f2 branch frequency error Specifically: represents the frequency difference f1, represents the observation noise at frequency f1, represents the frequency difference f2, represents the observation noise at frequency f2.

4. A high-orbit satellite dual-frequency weighted fusion frequency-locked loop GNSS tracking and reception method, characterized by: Use a dual-frequency GNSS antenna to simultaneously receive dual-frequency GNSS signals, with the two frequencies being f1 and f2. performing low-noise amplification on the dual-frequency GNSS signal; The frequency f1 signal and the frequency f2 signal are processed in sequence by a down-converter, an analog-to-digital converter, a mixer, a correlator, and a frequency discriminator; The output signals of the two correlators and Perform signal-to-noise ratio estimation to obtain the noise estimation value of the dual-frequency signal According to the frequency error of the f1 branch output by the two frequency discriminators and f2 branch frequency error Code phase observation and the noise estimate Determine whether the signal-to-noise ratio of the two signals exceeds the set threshold. When only one of the two signals has a signal-to-noise ratio that exceeds the set threshold, select the frequency error and code phase observation value of the signal that exceeds the set threshold to drive the frequency lock loop and the code loop respectively, obtain the carrier frequency control word and send it to the carrier NCO, and obtain the code frequency control word and send it to the code NCO; when the signal-to-noise ratio of both signals exceeds the set threshold, fuse the frequency error and code phase observation value, and use the fused frequency error and code observation fusion error to drive the frequency lock loop and the code loop respectively, obtain the carrier frequency control word and send it to the carrier NCO, and obtain the code frequency control word and send it to the code NCO; The carrier NCO generates a local carrier according to the carrier frequency control word and sends it to two mixers at the same time. The code NCO generates a local regenerative spread spectrum code according to the code frequency control word and sends it to two correlators at the same time. The signals output by the two correlators are and Specifically: where a i represents the amplitude of the i-th received signal, f represents the intermediate frequency, c i represents the spreading code of the i-th received signal, k represents the time, T coh represents the coherent integration time, and n f1 represents the residual carrier of the f1 branch signal and the noise of the f1 branch signal, and n f2 Indicates the residual carrier of the f2 branch signal and the noise of the f2 branch signal. When the loop is stable 5. The high-orbit satellite dual-frequency weighted fusion frequency-locked loop GNSS tracking and receiving method according to claim 4, characterized in that: The fusion of frequency error and code phase observation values ​​is specifically as follows: Fusion frequency error Code observation fusion error 6. The high-orbit satellite dual-frequency weighted fusion frequency-locked loop GNSS tracking and receiving method according to claim 5, characterized in that: The frequency error of the f1 branch output by the two frequency discriminators is and f2 branch frequency error Specifically: represents the f1 frequency error, represents the observation noise at frequency f1, represents the f2 frequency error, represents the observation noise at frequency f2.

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