Method and device for reacquiring a navigation satellite navigation signal by a receiver on board a missile

Abstract

The application discloses a method and device for a missile-borne receiver to reacquire a navigation satellite navigation signal after losing lock. The method comprises the following steps: receiving a first navigation satellite navigation signal, generating a first carrier estimated center frequency and a first pseudo code estimated phase according to stored information of the missile-borne body before losing lock, and generating a first simulated carrier signal of the missile-borne body according to the first carrier estimated center frequency and the first pseudo code estimated phase; performing correlation operation on the first navigation satellite navigation signal and the first simulated carrier signal to generate a first frequency bin initial value and a first pseudo code phase initial value of the first navigation satellite navigation signal, and inputting the first frequency bin initial value and the first pseudo code phase initial value into a first channel to search for a frequency bin and a pseudo code phase of the first navigation satellite navigation signal; searching for a frequency bin and a pseudo code phase of a second navigation satellite navigation signal in a second channel by using a similar method; and combining search results of the first channel and the second channel to determine the frequency bin and the pseudo code phase of the navigation satellite navigation signal, so that the navigation signal can be quickly reacquired after losing lock.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of navigation signal acquisition, in particular to a method and device for re-acquiring a navigation satellite navigation signal by a missile-borne receiver. BACKGROUND

[0002] For a missile-borne receiver, excessive acceleration, acceleration stress or rapid attitude change will cause the receiver to lose lock on the satellite navigation signal. In the prior art, a conventional signal acquisition method is usually used. Traditional signal acquisition mainly includes two parts: coarse acquisition and fine acquisition. Acquisition is a process of searching the received signal, and the approximate carrier frequency and code phase value of the transmitted signal are obtained by matching. The coarse acquisition process generally uses a cyclic correlation acquisition method based on FFT, INS and satellite ephemeris are used to predict Doppler information, and a two-dimensional search method is used to search the signal in the frequency and code phase directions.

[0003] In the implementation of the prior art, the inventors have found that:

[0004] Because the dynamic information of the platform is very large, according to the conventional acquisition method, the frequency range to be searched is very wide, which greatly affects the acquisition time.

[0005] Therefore, it is necessary to provide a related technical solution for fast re-acquisition of a lost lock with relatively short acquisition time. SUMMARY

[0006] The embodiments of the present application provide a related technical solution for fast re-acquisition of a lost lock with relatively short acquisition time, to solve the technical problem of long acquisition time in the prior acquisition method.

[0007] The method for re-acquiring a navigation satellite navigation signal by a missile-borne receiver provided by the present application includes the following steps:

[0008] Receiving a first navigation satellite navigation signal;

[0009] Generating a first carrier estimated center frequency and a first pseudo code estimated phase according to the stored information of the missile-borne body before the first navigation satellite navigation signal loses lock;

[0010] Generating a first simulated carrier signal of the missile-borne body according to the first carrier estimated center frequency and the first pseudo code estimated phase;

[0011] Performing correlation operation on the first navigation satellite navigation signal and the first simulated carrier signal to generate a first frequency bin initial value and a first pseudo code phase initial value of the first navigation satellite navigation signal;

[0012] Inputting the first frequency bin initial value and the first pseudo code phase initial value into a first channel to search for a frequency bin and a pseudo code phase of the first navigation satellite navigation signal;

[0013] receiving a second navigation satellite navigation signal;

[0014] generating a second carrier estimated center frequency and a second pseudo code estimated phase according to the stored information of the missile-borne body before the first navigation satellite navigation signal loses lock;

[0015] generating a second simulated carrier signal locally to the missile-borne body according to the second carrier estimated center frequency and the second pseudo code estimated phase;

[0016] performing correlation operation on the second navigation satellite navigation signal and the second simulated carrier signal to generate a second frequency bin initial value and a second pseudo code phase initial value of the second navigation satellite navigation signal;

[0017] inputting the second frequency bin initial value and the second pseudo code phase initial value into a second channel to search for the frequency bin and the pseudo code phase of the second navigation satellite navigation signal;

[0018] merging the search results of the first channel and the second channel to determine the frequency bin and the pseudo code phase of the navigation satellite navigation signal.

[0019] Further, generating a first carrier estimated center frequency and a first pseudo code estimated phase according to the stored information of the missile-borne body before the first navigation satellite navigation signal loses lock, specifically comprising:

[0020] generating a Doppler shift value of the first carrier estimated center frequency and the first pseudo code estimated phase according to the missile-borne body motion information before the first navigation satellite navigation signal loses lock;

[0021] generating the first carrier estimated center frequency and the first pseudo code estimated phase according to the Doppler shift value.

[0022] Further, generating a Doppler shift value of the first carrier estimated center frequency and the first pseudo code estimated phase according to the missile-borne body motion information before the first navigation satellite navigation signal loses lock, specifically comprising:

[0023] obtaining a missile-borne body motion speed V2 before the first navigation satellite navigation signal loses lock from the stored information of the missile-borne body;

[0024] obtaining a navigation satellite speed V1 before the first navigation satellite navigation signal loses lock from the stored information of the missile-borne body;

[0025] obtaining a vector e of a line of sight direction between the missile-borne body and the first navigation satellite from the stored information of the missile-borne body;

[0026] according to the formula:

[0027]

[0028] The Doppler shift value of the first carrier estimated center frequency and the first pseudo code estimated phase is calculated.

[0029] Further, the first carrier estimated center frequency is generated according to the Doppler shift value, and specifically includes:

[0030] According to the formula:

[0031]

[0032] The first carrier estimated center frequency value in the first precision range is calculated.

[0033] Further, the first carrier estimated center frequency is generated according to the Doppler shift value, and further includes:

[0034] At time N, find the highest frequency component in the navigation message sent by the navigation satellite in 1ms ;

[0035] At time N+T, which is T long from time N, find the frequency component in the preset intensity range in the navigation message sent by the navigation satellite in 1ms ;

[0036] The initial phase of the highest frequency component is calculated by the DFT algorithm :

[0037] ;

[0038] The initial phase of the frequency component is calculated by the DFT algorithm :

[0039] ;

[0040] The fine frequency is calculated according to the initial phase of the highest frequency component and the initial phase of the frequency component

[0041]

[0042] According to the formula: (higher than the first precision range), the first carrier estimated center frequency in the second precision range is calculated.

[0043] Further, the first pseudo code estimated phase is generated according to the Doppler shift value, and further includes:

[0044] From the storage information of the missile-borne body, the first carrier phase of the first navigation satellite before the first navigation satellite loses lock is obtained.​​​

[0045] The first carrier phase reference Doppler shift value is used to generate a first code phase estimation.

[0046] Further, the first navigation satellite navigation signal is received, specifically comprising:

[0047] In the navigation satellite list, the first navigation satellite is determined.

[0048] The first navigation satellite navigation signal is received.

[0049] Further, in the navigation satellite list, the first navigation satellite is determined, specifically comprising:

[0050] From the storage information of the missile-borne body, the missile-borne body position information, the missile-borne body attitude information, the ephemeris information of the navigation satellite and the antenna installation position information are obtained.

[0051] According to the missile-borne body position information, the missile-borne body attitude information, the ephemeris information of the navigation satellite and the antenna installation position information, a navigation satellite lock loss recapture list is screened from the navigation satellite list.

[0052] In the navigation satellite lock loss recapture list, the first navigation satellite is determined.

[0053] The application also provides a missile-borne receiver for a navigation satellite navigation signal lock loss recapture device, comprising:

[0054] The first receiving module is used to receive the first navigation satellite navigation signal.

[0055] The first estimation module is used to generate a first carrier estimation center frequency and a first code phase estimation according to the storage information of the missile-borne body before the first navigation satellite navigation signal loses lock.

[0056] The first processing module is used to generate a first simulated carrier signal of the missile-borne body according to the first carrier estimation center frequency and the first code phase estimation, and is also used to perform correlation operation on the first navigation satellite navigation signal and the first simulated carrier signal to generate a first frequency bin initial value and a first code phase initial value of the first navigation satellite navigation signal, and is also used to input the first frequency bin initial value and the first code phase initial value into the first channel to search for the frequency bin and the code phase of the first navigation satellite navigation signal.

[0057] The second receiving module is used to receive the second navigation satellite navigation signal.

[0058] The second estimation module is used to generate a second carrier estimation center frequency and a second code phase estimation according to the storage information of the missile-borne body before the second navigation satellite navigation signal loses lock.

[0059] The second processing module is configured to generate a second analog carrier signal local to the missile according to the second carrier estimated center frequency and the second pseudo code estimated phase, and to perform correlation operation on the second navigation satellite navigation signal and the second analog carrier signal to generate a second frequency bin initial value and a second pseudo code phase initial value of the second navigation satellite navigation signal, and to input the second frequency bin initial value and the second pseudo code phase initial value into the second channel to search for the frequency bin and the pseudo code phase of the second navigation satellite navigation signal.

[0060] The merging module is configured to merge the search results of the first channel and the second channel to determine the frequency bin and the pseudo code phase of the navigation satellite navigation signal.

[0061] Further, the first estimation module is specifically configured to:

[0062] generate a Doppler shift value of the first carrier estimated center frequency and the first pseudo code estimated phase according to the missile motion information before the first navigation satellite navigation signal loses lock;

[0063] generate the first carrier estimated center frequency and the first pseudo code estimated phase according to the Doppler shift value.

[0064] The embodiments provided in the present application have at least the following beneficial effects:

[0065] The first frequency bin initial value and the first pseudo code phase initial value are generated by receiving the first navigation satellite navigation signal and performing a series of serial operations, and the first channel is inputted to search for the frequency bin and the pseudo code phase of the first navigation satellite navigation signal, the second frequency bin initial value and the second pseudo code phase initial value are generated by receiving the second navigation satellite navigation signal and performing a series of serial operations, and the second channel is inputted to search for the frequency bin and the pseudo code phase of the second navigation satellite navigation signal, the frequency bin and the pseudo code phase of the navigation satellite navigation signal are determined in a parallel manner by combining the search results of the two times, the search range of the frequency and the code phase is reduced, and the fast lock loss recapture in a high dynamic condition with a relatively short capture time is realized. BRIEF DESCRIPTION OF DRAWINGS

[0066] The accompanying drawings, which are included to provide a further understanding of the present application, form a part of the present application and illustrate the illustrative embodiments of the present application and its description are used to explain the present application and do not constitute improper limitations on the present application. In the drawings:

[0067] Figure 1 The high-precision trajectory measurement verification receiver design principle block diagram provided for the embodiments of the present application;

[0068] Figure 2 The missile-borne positioning and attitude measurement integrated receiver hardware block diagram provided for the embodiments of the present application;

[0069] Figure 3A schematic diagram of generating pseudo code phase and carrier Doppler in the serial-parallel combined frequency search method provided by the embodiments of the present application;

[0070] Figure 4 A schematic diagram of introducing external velocity assistance in the serial-parallel combined frequency search method provided by the embodiments of the present application;

[0071] Figure 5 A schematic diagram of frequency bin range when using the common frequency search method provided by the embodiments of the present application;

[0072] Figure 6 A schematic diagram of frequency bin range when using the serial-parallel frequency search method provided by the embodiments of the present application;

[0073] Figure 7 A schematic diagram of a lock loss recapturing device of a missile-borne receiver for a navigation satellite navigation signal provided by the embodiments of the present application.

[0074] 100 lock loss recapturing device

[0075] 11 first receiving module

[0076] 12 first estimation module

[0077] 13 first processing module

[0078] 14 second receiving module

[0079] 15 second estimation module

[0080] 16 second processing module

[0081] 17 merging module DETAILED DESCRIPTION

[0082] In order to make the objectives, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described below in connection with the embodiments of the present application and the corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative work fall within the scope of protection of the present application.

[0083] The satellite navigation receiving system on the missile completes device initialization and self-checking state confirmation after starting. The receiver on the missile completes receiver capture and tracking positioning quickly after the shot is fired, and saves pseudorange and carrier observation data at the same time. The trajectory observation data stored by the missile device and the observation data collected by the reference station device are imported into the post-processing analysis software for differential positioning calculation, which is used as the reference on the missile to evaluate the trajectory measurement accuracy of the satellite navigation device on the missile. The post-processing analysis software gives the final analysis and evaluation results, including error size, error characteristics of each segment, etc., which are used for the positioning of the navigation receiver on the guided missile and the improvement of the control strategy. Please refer to the design principle block diagram of the high-precision trajectory measurement verification receiver in Figure 1 The high-precision trajectory measurement verification receiver specifically includes a combiner and frequency converter module, a GNSS verification receiver board. The GNSS verification receiver board specifically includes a signal correlation processing module, a loop filter processing module, a vector joint processing module, a loop control module, a satellite navigation information processing module, and a roll tracking loop processing module. GNSS represents Global Navigation Satellite System. The missile-borne GNSS antenna is used to receive signals and transmit the received signals to the combiner and frequency converter module, which is transmitted to the GNSS verification receiver board for processing after preliminary processing. The battery module serves as the power supply for the high-precision trajectory measurement receiver.

[0084] The high-precision trajectory measurement receiver can also be understood as a high-precision trajectory measurement verification receiver. When designing a high-precision trajectory measurement receiver in a high-dynamic environment, the receiver is designed to be small in size, low in power consumption, and capable of receiving Beidou satellite signals. From the structural point of view, the entire trajectory measurement system is composed of the original missile-borne Beidou navigation terminal, the high-precision trajectory measurement verification receiver, the missile-borne verification data storage module, the antenna, and the missile-borne power supply, etc. When designing the high-precision trajectory measurement verification receiver, the radio frequency receiver can use MAX2769 chip, and the baseband part uses DSP+FPGA architecture to complete baseband signal processing. The power consumption of the high-precision trajectory measurement verification receiver is about 2W. The high-precision trajectory measurement verification receiver can also be understood as a missile-borne satellite positioning and attitude measurement integrated receiver. Its hardware design structure block diagram is shown in Figure 2The radio frequency part using the MAX2769 chip includes two low noise amplifiers LNA-B3 covering the B3 frequency point, frequency conversion, crystal oscillator, clock driving, etc. The baseband part can use the EP3C80 chip, and the DSP can use the TMS320C6748 chip. The high-precision trajectory measurement verification receiver in high dynamic environment is divided into radio frequency and baseband parts. The radio frequency part mainly completes the following tasks: filtering and amplifying satellite signals, mixing and sampling, and outputting 4-bit digital intermediate frequency for baseband part to process signals and information; receiving the BPSK signal provided by the baseband part, mixing and amplifying it to the antenna. The DSP and FPGA of the baseband part cooperate to complete the capture and tracking of the intermediate frequency signal.

[0085] The application provides a method for a missile-borne receiver to lose lock and recapture a navigation satellite navigation signal based on the high-precision trajectory measurement verification receiver in the high dynamic environment, which comprises the following steps:

[0086] S10: receiving a first navigation satellite navigation signal;

[0087] S11: generating a first carrier estimated center frequency and a first pseudo code estimated phase according to the storage information of the missile-borne body before the first navigation satellite navigation signal loses lock;

[0088] S12: generating a first analog carrier signal of the missile-borne body locally according to the first carrier estimated center frequency and the first pseudo code estimated phase;

[0089] S13: performing correlation operation on the first navigation satellite navigation signal and the first analog carrier signal to generate a first frequency bin initial value and a first pseudo code phase initial value of the first navigation satellite navigation signal;

[0090] S14: inputting the first frequency bin initial value and the first pseudo code phase initial value into a first channel to search the frequency bin and the pseudo code phase of the first navigation satellite navigation signal;

[0091] S15: receiving a second navigation satellite navigation signal;

[0092] S16: generating a second carrier estimated center frequency and a second pseudo code estimated phase according to the storage information of the missile-borne body before the second navigation satellite navigation signal loses lock;

[0093] S17: generating a second analog carrier signal of the missile-borne body locally according to the second carrier estimated center frequency and the second pseudo code estimated phase;

[0094] S18: performing correlation operation on the second navigation satellite navigation signal and the second analog carrier signal to generate a second frequency bin initial value and a second pseudo code phase initial value of the second navigation satellite navigation signal;

[0095] S19: inputting the second frequency bin initial value and the second pseudo code phase initial value into the second channel to search the frequency bin and the pseudo code phase of the second navigation satellite navigation signal;

[0096] S20: merging the search results of the first channel and the second channel to determine the frequency bin and the pseudo code phase of the navigation satellite navigation signal.

[0097] It can be understood that for a missile-borne receiver, excessive acceleration, acceleration stress or rapid attitude change will all lead to the loss of lock of the receiver to the satellite navigation signal. When the loss of lock recapturing is performed, the first navigation satellite navigation signal is received, and the carrier estimated center frequency and the pseudo code estimated phase of the corresponding navigation satellite are generated according to the information stored by the missile-borne body before the loss of lock. According to the carrier estimated center frequency and the pseudo code estimated phase, the corresponding analog carrier signal is generated locally in the missile-borne body. At this time, the first navigation satellite navigation signal and the analog carrier signal are correlated to generate the frequency bin initial value and the pseudo code phase initial value of the navigation satellite navigation signal. At this time, the corresponding frequency bin initial value and the pseudo code phase initial value can be used to search the frequency bin and the pseudo code phase of the first navigation satellite navigation signal through the corresponding first channel. When the frequency bin and the pseudo code phase of the second navigation satellite navigation signal are searched, the same method as that for searching the frequency bin and the pseudo code phase of the first navigation satellite navigation signal can be used to search the frequency bin and the pseudo code phase of the second navigation satellite navigation signal through the corresponding second channel. Finally, through the comprehensive search results of the two, the frequency bin and the pseudo code phase of the navigation satellite navigation signal can be accurately and efficiently determined.

[0098] Further, the first carrier estimated center frequency and the first pseudo code estimated phase are generated according to the stored information of the missile-borne body before the loss of lock of the first navigation satellite navigation signal, and specifically include:

[0099] According to the missile-borne body motion information before the loss of lock of the first navigation satellite navigation signal, a Doppler shift value of the first carrier estimated center frequency and the first pseudo code estimated phase is generated;

[0100] According to the Doppler shift value, the first carrier estimated center frequency and the first pseudo code estimated phase are generated.

[0101] It should be noted that Doppler frequency shift can be understood as the difference between the transmitted and received frequencies caused by the Doppler effect. The stored information on the missile carrier can be found in the data stored before the first navigation satellite signal was lost, and further, the corresponding motion information of the missile carrier at that time can be found. Based on the motion information, the corresponding Doppler frequency shift value can be calculated, and thus the estimated center frequency of the first carrier and the estimated phase of the first pseudocode can be finally calculated. The motion information of the missile carrier is generated under the combined effect of various data. Calculating the corresponding Doppler frequency shift value using the missile carrier's motion information is more accurate, and the final estimated center frequency of the first carrier and the estimated phase of the first pseudocode are closer to the true center frequency of the carrier and the pseudocode phase.

[0102] Specifically, based on the launch vehicle motion information before the first navigation satellite navigation signal is lost, Doppler frequency shift values ​​for the first carrier predicted center frequency and the first pseudo-code predicted phase are generated, including:

[0103] The velocity V2 of the missile carrier before losing the first navigation satellite navigation signal is obtained from the stored information of the missile carrier;

[0104] Obtain the velocity V1 of the navigation satellite before the first navigation satellite's navigation signal is lost from the stored information on the missile carrier;

[0105] Obtain the vector e of the line-of-sight direction between the missile carrier and the first navigation satellite from the stored information of the missile carrier;

[0106] According to the formula:

[0107]

[0108] The Doppler shift values ​​of the estimated center frequency of the first carrier and the estimated phase of the first pseudocode are calculated.

[0109] It should be noted that during the coarse acquisition phase, by combining information from before the loss of lock and ephemeris data, the velocity and acceleration of the carrier and satellite can be obtained, thus allowing the calculation of the Doppler shift. The calculated frequency shift is fed back to the carrier NCO to jointly adjust the local carrier frequency center value. To better utilize the frequency shift estimate, receiver information fusion should be placed early in the acquisition process. Assume the satellite navigation signal is in... The carrier wavelength of the band is The frequency is The speed of the projectile carrier The speed of the navigation satellite is The satellite carrier's unit line-of-sight vector is The estimated Doppler frequency shift caused by the movement of the carrier :

[0110]

[0111] The velocity V2 of the carrier is estimated by the pre-lock information, the velocity V1 of the satellite is calculated by the ephemeris, and the vector e of the line-of-sight direction of the carrier and the satellite can be calculated by the satellite position information provided by the ephemeris. The Doppler shift estimation value is calculated by the velocity of the carrier, the velocity of the navigation satellite and the vector of the line-of-sight direction of the satellite, and the calculated data is more accurate. The Doppler shift value of the first carrier estimated center frequency and the first pseudo code estimated phase can be understood as the Doppler shift estimation value.

[0112] Please refer to Figure 3 and Figure 4 Compared with the conventional search method, the external velocity assistance is introduced after the acquisition control in the present application. The external velocity assistance can also be understood as the external velocity assistance information, which can be used to accurately calculate the Doppler shift value of the frequency and the code, and then the more accurate frequency shift value calculated is calculated into the carrier NCO and the code NCO, so as to control the local carrier and code generator, reduce the search range of the frequency and the code phase, and make the local signal quickly reproduce the satellite transmitted signal.

[0113] For the serial correlation acquisition method, if the GPS signal L1 frequency point is taken as an example, 2046 searches are required to traverse all the pseudo code phases, which greatly increases the acquisition time. If the number of pseudo code phase searches can be reduced, and the search range can be fixed within a few chips, the acquisition speed can be greatly improved, thereby reducing the signal search time. The FFT parallel code phase acquisition method only needs one operation to complete the pseudo code phase search. We use the external INS information and the FFT parallel code phase one operation as a guide to obtain the approximate position of the frequency bin and the pseudo code phase, and then perform fine search in the serial correlation mode. At the same time, the FFT module is only used as a guide, so it can be used in a multiplexing manner to guide the acquisition of multiple channels. After completing the guide work of one channel each time, it can be switched to the next channel until the guide of all channels is completed. First, like the parallel acquisition method, the discrete-time intermediate frequency signal enters the front-end FFT guide module for processing, which is essentially a parallel code phase acquisition based on FFT. After the acquisition is completed, the guide module transmits the satellite number, the carrier Doppler and the pseudo code phase coarse value of the acquired satellite to the acquisition controller, and then continues the coarse acquisition. The acquisition controller distributes the received measurement values to the idle channels for fine acquisition, and then sends the fine measurement results to the tracking module.

[0114] The GPS No. 24 satellite is captured respectively, please refer to Figure 5 for the frequency bin range diagram provided by the embodiment of the present application when the ordinary frequency search method is used. Please refer to Figure 6The frequency bin range diagram provided by the embodiment of the application when using the serial-parallel frequency search method. The serial-parallel frequency search method herein can be understood as the method for the on-board receiver to reacquire the navigation satellite navigation signal when losing lock.

[0115] From Figure 5 and Figure 6 it can be seen that Figure 6 the improved search method is smaller than the general search method in Figure 5 the frequency bin range, and is only about one-eighth of the search range of the latter, so the signal acquisition time is significantly reduced.

[0116] Further, according to the Doppler shift value, a first carrier estimated center frequency is generated, specifically including:

[0117] According to the formula:

[0118]

[0119] The first carrier estimated center frequency value in the first accuracy range is calculated.

[0120] It can be understood that f L1 is the frequency of the satellite navigation signal in the L1 band, is the Doppler shift estimation value due to the movement of the carrier, f c is the local carrier frequency estimation value. At this point, the carrier center frequency can be accurately estimated, the frequency search interval is reduced, and the signal can be quickly acquired.

[0121] Specifically, according to the Doppler shift value, a first carrier estimated center frequency is generated, and further includes:

[0122] At time N, find the highest frequency component in the navigation message sent by the navigation satellite in 1ms ;

[0123] At time N+T, which is T long from time N, find the frequency component in the preset intensity range in the navigation message sent by the navigation satellite in 1ms ;

[0124] Calculate the initial phase of the highest frequency component by the DFT algorithm:

[0125] ;

[0126] Calculate the initial phase of the frequency component by the DFT algorithm:

[0127] ;

[0128] Based on the highest frequency component initial phase and frequency components initial phase Calculate fine frequency

[0129]

[0130] According to the formula: (Here f=fc), the estimated center frequency of the first carrier in the second precision range, which is higher than the first precision range, is calculated.

[0131] It should be noted that in the case of coarse capture, the search range of each search grid is relatively large. If T is selected... coh =1ms navigation message data, frequency locking loop with When used as a frequency discriminator, its frequency pull-in range is wide. The corresponding frequency pull-in range is ±500Hz, where: This is too coarse for a tracking loop, whose operating bandwidth is typically a few Hz or tens of Hz. Therefore, the frequency must be finely processed to meet the bandwidth requirements of the tracking loop.

[0132] If the locally generated signal and the input signal code are phase-matched, multiplying them will result in a continuous input signal. Assume that at time N, the highest frequency component in the 1ms navigation message is found to be... At a very short time interval T after N moments, another component with a high frequency appears. Generally, the fine frequency required to meet the tracking loop can be obtained through phase analysis, and it can be calculated using the DFT algorithm. initial phase :

[0133] ;

[0134] Im and Re represent the imaginary and real parts, respectively. Then, at time T... initial phase for:

[0135] ;

[0136] Based on the highest frequency component initial phase and frequency components initial phase The fine frequency can be calculated as follows:

[0137]

[0138] The carrier frequency at this time is Wherein f=fc. The frequency estimation value f obtained by calculation again is T More accurate, can meet the frequency requirements required by the tracking process. The frequency estimation value f T It can be understood that the first carrier pre-estimation center frequency in the second accuracy range higher than the first accuracy range is calculated.

[0139] Further, according to the Doppler shift value, the first pseudo code pre-estimation phase is generated, and further comprising:

[0140] From the storage information of the missile-borne body, the first carrier phase of the first navigation satellite before the first navigation satellite signal loses lock is obtained;

[0141] The first carrier phase is referenced to the Doppler shift value to generate the first pseudo code pre-estimation phase.

[0142] It should be noted that the storage information of the missile-borne body saves a plurality of signal parameters before losing lock. The storage information can be increased or decreased according to actual conditions. The storage information can include the carrier phase of the navigation satellite stored in advance. The carrier phase can be stored one by one according to the identity information of the corresponding navigation satellite, such as the first carrier phase corresponding to the first navigation satellite. Since the storage information of the missile-borne body is derived from real environment data, the first carrier phase obtained is more accurate, and the first pseudo code pre-estimation phase generated by combining the Doppler shift value is closer to the real first pseudo code phase.

[0143] Specifically, the first navigation satellite signal is received, specifically including:

[0144] In the navigation satellite list, the first navigation satellite is determined;

[0145] The first navigation satellite signal is received.

[0146] It should be noted that after the satellite signal loses lock, the first navigation satellite is determined through the navigation satellite list, which can reduce the blind search of invisibility, thereby narrowing the search range and reducing the search time, and providing the possibility for the final rapid implementation of lock recapture. The first navigation satellite here can be understood as the current visible satellite.

[0147] Further, in the navigation satellite list, the first navigation satellite is determined, specifically including:

[0148] From the storage information of the missile-borne body, the missile-borne body position information, the missile-borne body attitude information, the ephemeris information of the navigation satellite and the antenna installation position information are obtained;

[0149] According to the missile-borne body position information, the missile-borne body attitude information, the ephemeris information of the navigation satellite and the antenna installation position information, a navigation satellite lock-loss recapture list is screened from a navigation satellite list;

[0150] In the navigation satellite lock-loss recapture list, a first navigation satellite is determined.

[0151] It should be noted that after the satellite signal loses lock, the visible satellites need to be determined in time. By using the known storage information of the missile-borne body, the missile-borne body position information, the missile-borne body attitude information, the ephemeris information of the navigation satellite and the antenna installation position information on the body, the current actual visible star map can be calculated in real time. After the navigation satellite loses lock, the visible satellites are quickly judged and added to the lock-loss recapture list, so as to reduce the blind search of invisibility. After the satellite signal loses lock, the related information of the channel before losing lock and the carrier phase can also be reserved, and the interrupted site can be quickly recovered after the capture is completed. In the case of coarse capture, each search range of the search frequency grid is relatively large. The application reduces the blind search of invisibility and quickly recovers the interrupted site, improves the search performance of the receiver, completes the signal tracking from the transient state to the steady state, and thus controls the lock-loss recapture time within the index range. The technical index reached by the application in the lock-loss recapture is that when the acceleration is less than or equal to 5g, the repositioning time within 5s after losing lock is less than 2s; and when the acceleration is less than or equal to 10g, the repositioning within 5s after losing lock is less than 8s. The influence of acceleration on capture is mainly that the code chip slides due to the change of acceleration after losing lock. The application reduces the influence of acceleration on the capture speed by using the capture of the full code phase. In the high-dynamic measurement terminal, the position and velocity information of the body can be accurately measured under the condition that the satellite navigation signal is invalid for a short time, and the actual visible star information and the relative motion condition thereof can be obtained in real time in combination with the satellite ephemeris.

[0152] Please refer to Figure 7 The application also provides a missile-borne receiver for lock-loss recapture of a navigation satellite navigation signal 100, which comprises:

[0153] A first receiving module 11 is configured to receive a first navigation satellite navigation signal.

[0154] A first estimation module 12 is configured to generate a first carrier estimated center frequency and a first pseudo-code estimated phase according to the storage information of the missile-borne body before the first navigation satellite navigation signal loses lock.

[0155] The first processing module 13 is configured to generate a first analog carrier signal local to the missile-borne device according to a first carrier estimated center frequency and a first pseudo code estimated phase, and to perform correlation operation on the first navigation satellite navigation signal and the first analog carrier signal to generate a first frequency bin initial value and a first pseudo code phase initial value of the first navigation satellite navigation signal, and to input the first frequency bin initial value and the first pseudo code phase initial value into the first channel to search for the frequency bin and the pseudo code phase of the first navigation satellite navigation signal.

[0156] The second receiving module 14 is configured to receive a second navigation satellite navigation signal.

[0157] The second estimation module 15 is configured to generate a second carrier estimated center frequency and a second pseudo code estimated phase according to the stored information of the missile-borne device before the second navigation satellite navigation signal loses lock.

[0158] The second processing module 16 is configured to generate a second analog carrier signal local to the missile-borne device according to the second carrier estimated center frequency and the second pseudo code estimated phase, and to perform correlation operation on the second navigation satellite navigation signal and the second analog carrier signal to generate a second frequency bin initial value and a second pseudo code phase initial value of the second navigation satellite navigation signal, and to input the second frequency bin initial value and the second pseudo code phase initial value into the second channel to search for the frequency bin and the pseudo code phase of the second navigation satellite navigation signal.

[0159] The merging module 17 is configured to merge the search results of the first channel and the second channel to determine the frequency bin and the pseudo code phase of the navigation satellite navigation signal.

[0160] It can be understood that for the missile-borne receiver, excessive acceleration, acceleration stress or rapid attitude change will cause the receiver to lose lock on the satellite navigation signal. When the missile-borne receiver loses lock and recaptures the navigation satellite navigation signal, the carrier estimated center frequency and the pseudo code estimated phase corresponding to the navigation satellite can be generated according to the information stored by the missile-borne device before losing lock. According to the carrier estimated center frequency and the pseudo code estimated phase, the corresponding analog carrier signal local to the missile-borne device can be generated. At this time, the correlation operation can be performed on the navigation satellite navigation signal and the analog carrier signal to generate the frequency bin initial value and the pseudo code phase initial value of the navigation satellite navigation signal. Thus, the corresponding frequency bin initial value and the pseudo code phase initial value can be input into the corresponding first channel to search for the frequency bin and the pseudo code phase of the first navigation satellite navigation signal. Further, the same method as the search for the frequency bin and the pseudo code phase of the first navigation satellite navigation signal can be used to search for the frequency bin and the pseudo code phase of the second navigation satellite navigation signal through the corresponding second channel. Finally, the search results of the two can be combined to accurately and efficiently determine the frequency bin and the pseudo code phase of the navigation satellite navigation signal.

[0161] Further, the first estimation module 12 is specifically configured to:

[0162] According to the Doppler shift value, the first estimated center frequency of the first carrier and the first estimated phase of the first pseudo code are generated.

[0163] According to the Doppler shift value, the first estimated center frequency of the first carrier and the first estimated phase of the first pseudo code are generated.

[0164] It should be noted that the Doppler shift can be understood as the difference between the transmitted and received frequencies due to the Doppler effect. In the storage information of the missile-borne body, the data information stored before the first navigation satellite navigation signal loses lock can be found, and further the motion information of the missile-borne body corresponding to the time can be found. According to the motion information, the corresponding Doppler shift value can be calculated, and the first estimated center frequency of the first carrier and the first estimated phase of the first pseudo code are finally calculated.

[0165] Specifically, according to the Doppler shift value of the first estimated center frequency of the first carrier and the first estimated phase of the first pseudo code before the first navigation satellite navigation signal loses lock, the first navigation satellite navigation signal loses lock, and the first navigation satellite navigation signal loses lock. The specific steps include:

[0166] From the storage information of the missile-borne body, the motion speed V2 of the missile-borne body before the first navigation satellite navigation signal loses lock is obtained;

[0167] From the storage information of the missile-borne body, the speed V1 of the navigation satellite before the first navigation satellite navigation signal loses lock is obtained;

[0168] From the storage information of the missile-borne body, the vector e of the line-of-sight direction of the missile-borne body and the first navigation satellite is obtained;

[0169] According to the formula:

[0170]

[0171] The Doppler shift value of the first estimated center frequency of the first carrier and the first estimated phase of the first pseudo code is calculated.

[0172] It should be noted that in the coarse acquisition stage, the speed and acceleration of the carrier and the satellite are provided by combining the pre-lock information and the ephemeris, so that the Doppler shift The calculated frequency shift is fed back to the carrier NCO to jointly adjust the local carrier frequency center value. In order to better utilize the frequency shift estimation, the receiver information fusion should be placed in an early position in the acquisition process. Assuming that the satellite navigation signal is in the carrier wavelength is , the frequency is , the motion speed of the carrier is , the satellite speed is , and the unit line-of-sight vector of the satellite carrier is Doppler shift estimation value due to carrier movement :

[0173]

[0174] The velocity V2 of the carrier is estimated by the pre-loss information, the velocity V1 of the satellite is obtained by the ephemeris, and the vector e of the line-of-sight direction of the carrier and the satellite can be calculated by using the satellite position information provided by the ephemeris.

[0175] Please refer to Figure 3 and Figure 4 Compared with the conventional search method, the external velocity assistance is introduced after the acquisition control in the present application. The external velocity assistance can also be understood as external velocity assistance information, which can be used to accurately calculate the Doppler shift values of the frequency and code, and then the more accurate frequency shift values calculated are calculated into the carrier NCO and code NCO, so as to control the local carrier and code generators, reduce the search range of the frequency and code phase, and enable the local signal to quickly reproduce the satellite transmitted signal.

[0176] For the serial correlation acquisition method, if the GPS signal L1 frequency point is taken as an example, 2046 searches are required to traverse all the pseudo-code phases, which greatly increases the acquisition time. If the number of pseudo-code phase searches can be reduced, and the search range can be fixed within a few chips, the acquisition speed can be greatly improved, thereby reducing the signal search time. The FFT parallel code phase acquisition method only needs one operation to complete the pseudo-code phase search. We use the external INS information and the FFT parallel code phase one-time operation as a guide to first obtain the approximate position of the frequency bin and the pseudo-code phase, and then perform fine search in the serial correlation mode. At the same time, the FFT module is only used for guidance, so it can be used in a multiplexing manner to guide the acquisition of multiple channels. After completing the guidance work of one channel each time, it can be switched to the next channel until the guidance of all channels is completed. First, like the parallel acquisition method, the discrete-time intermediate frequency signal enters the front-end FFT guidance module for processing, which is essentially a parallel code phase acquisition based on FFT. After completion of the acquisition, the guidance module transmits the satellite number, carrier Doppler, and pseudo-code phase coarse value of the acquired satellite to the acquisition controller, and then continues the coarse acquisition. The acquisition controller distributes the received measurement values to the idle channels for fine acquisition, and then sends the fine measurement results to the tracking module.

[0177] Capture of the 24th satellite of GPS, please refer to Figure 5 for the frequency bin range diagram provided by the embodiment of the present application when using the ordinary frequency search method. Please refer to Figure 6The frequency range diagram provided by the embodiment of the application when using the serial-parallel frequency search method. The serial-parallel frequency search method herein can be understood as the method of the on-board receiver of the application for reacquiring the navigation satellite navigation signal when losing lock.

[0178] From Figure 5 and Figure 6 It can be seen that Figure 6 the improved search method in the application has a smaller frequency range than the general search method in the application, which is about one-eighth of the search range of the latter, so the signal acquisition time is significantly reduced. Figure 5

[0179] Further, according to the Doppler shift value, a first carrier estimated center frequency is generated, specifically including:

[0180] According to the formula:

[0181]

[0182] The first carrier estimated center frequency value in the first accuracy range is calculated.

[0183] It can be understood that f L1 is the frequency of the satellite navigation signal in the L1 band, is the Doppler shift estimation value due to the movement of the carrier, and f c is the local carrier frequency estimation value. At this point, the carrier center frequency can be accurately estimated, the frequency search interval is reduced, and the signal can be quickly acquired.

[0184] Specifically, according to the Doppler shift value, a first carrier estimated center frequency is generated, further including:

[0185] At time N, find the highest frequency component in the navigation message sent by the navigation satellite in 1ms ;

[0186] At time N+T, which is T long from time N, find the frequency component in the preset intensity range in the navigation message sent by the navigation satellite in 1ms ;

[0187] The initial phase of the highest frequency component is calculated by the DFT algorithm:

[0188] ;

[0189] The initial phase of the frequency component is calculated by the DFT algorithm:

[0190] ; ​​​

[0191] the initial phase of the highest frequency component the initial phase of the frequency component the fine frequency

[0192]

[0193] According to the formula: (the first carrier estimated center frequency is calculated in the second accuracy range higher than the first accuracy range).

[0194] It should be noted that in the case of coarse acquisition, each search range of the search frequency grid is relatively large, if the navigation message data of T coh =1ms is selected, the frequency pulling-in range of the frequency-locked loop is when the frequency discriminator is , and the corresponding frequency pulling-in range is ±500Hz, wherein: This is too rough for the tracking loop, and the working bandwidth of the tracking loop is generally several Hz or tens of Hz, so the frequency must be finely processed to meet the bandwidth requirement of the tracking loop.

[0195] If the local generated signal is phase-matched with the input signal code, the multiplication is performed, and then the input signal becomes a continuous signal. Assuming that at time N, the highest frequency component in the 1ms navigation message is found , and at time T after a short time interval from time N, a very strong component appears, the fine frequency that meets the tracking loop requirement can be obtained through the phase method, and the initial phase of :

[0196] ;

[0197] Im and Re represent the imaginary part and the real part respectively, and then the initial phase of at time T after the same time is:

[0198] ;

[0199] According to the initial phase of the highest frequency component and the initial phase of the frequency component , the fine frequency is calculated as:

[0200] ​​​​​​

[0201] The carrier frequency at this time is Where f=fc. The frequency estimate f T More accurate, can meet the frequency requirements required by the tracking process. The frequency estimate f T It can be understood that the first carrier pre-estimated center frequency in the second accuracy range higher than the first accuracy range is calculated.

[0202] Further, according to the Doppler shift value, the first pseudo code pre-estimated phase is generated, and further comprising:

[0203] From the storage information of the missile-borne body, the first carrier phase of the first navigation satellite before the first navigation satellite loses lock is obtained;

[0204] The first carrier phase is referenced to the Doppler shift value to generate the first pseudo code pre-estimated phase.

[0205] It should be noted that the storage information of the missile-borne body stores a plurality of signal parameters before losing lock. The storage information can be increased or decreased according to actual conditions. The storage information can include the carrier phase of the navigation satellite stored in advance. The carrier phase can be stored one by one according to the identity information of the corresponding navigation satellite, such as the first carrier phase corresponding to the first navigation satellite.

[0206] Specifically, the first receiving module 11 specifically includes:

[0207] In the navigation satellite list, the first navigation satellite is determined;

[0208] The first navigation satellite navigation signal is received.

[0209] It should be noted that after the satellite signal loses lock, the first navigation satellite is determined through the navigation satellite list, which can reduce the blind search of invisibility. The first navigation satellite here can be understood as the current visible satellite.

[0210] Further, in the navigation satellite list, the first navigation satellite is determined, specifically including:

[0211] From the storage information of the missile-borne body, the missile-borne body position information, the missile-borne body attitude information, the ephemeris information of the navigation satellite, and the antenna installation position information are obtained;

[0212] According to the missile-borne body position information, the missile-borne body attitude information, the ephemeris information of the navigation satellite, and the antenna installation position information, the navigation satellite loss recapture list is screened from the navigation satellite list;

[0213] In the navigation satellite loss recapture list, the first navigation satellite is determined.

[0214] It should be noted that after the satellite signal is lost, the visible satellites need to be determined in time. By using the known storage information of the missile-borne body, the current actual visible star map can be calculated in real time through the missile-borne body position information, the missile-borne body attitude information, the ephemeris information of the navigation satellite and the installation position information of the antenna on the carrier. After the navigation satellite is lost, the visible satellites are quickly judged, and the visible satellites are added to the lost recapture list to reduce the blind search of invisibility. After the satellite signal is lost, the related information of the channel before the loss about the time and the carrier phase can be reserved, and the interrupted site can be quickly recovered after the capture is completed. In the case of coarse capture, each search range of the search frequency grid is relatively large. The application reduces the blind search of invisibility and quickly recovers the interrupted site, improves the search performance of the receiver, completes the signal tracking from the transient state to the steady state process, and thus controls the lost recapture time within the index range. The technical index reached by the application in the lost recapture is that when the acceleration is less than or equal to 5g, the repositioning time is less than 2s within 5s after the loss; and when the acceleration is less than or equal to 10g, the repositioning is less than 8s within 5s after the loss. The influence of acceleration on capture is mainly that the code chip slides due to the change of acceleration after the loss. By using the capture of the full code phase, the application reduces the influence of acceleration on the capture speed, and in the high dynamic measurement terminal, the position and speed information of the carrier can be accurately measured under the condition that the satellite navigation signal is invalid for a short time, and the actual visible star information and the relative motion condition thereof can be obtained in real time combined with the satellite ephemeris.

[0215] It should also be noted that the terms "comprising", "containing", or any other similar term are intended to encompass non-exclusive inclusions, such that a process, method, article, or apparatus that comprises a list of elements does not necessarily include only those elements, but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without more limitations, the element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0216] Those skilled in the art will appreciate that embodiments of the present application can be provided as methods, systems or computer program products. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product embodied in one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) having computer-usable program code embodied therein.

[0217] The above merely provides an example of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the scope of claims of the present application.

Claims

1. A method for a reacquisition of a loss of lock of a navigation satellite navigation signal by a receiver on board a satellite, characterized in that, The method comprises the following steps: receiving a first navigation satellite navigation signal; generating a first carrier estimated center frequency and a first pseudo code estimated phase according to the stored information of the missile-borne body before losing lock of the first navigation satellite navigation signal; generating a first simulated carrier signal locally to the missile-borne body according to the first carrier estimated center frequency and the first pseudo code estimated phase; performing correlation operation on the first navigation satellite navigation signal and the first simulated carrier signal to generate a first frequency bin initial value and a first pseudo code phase initial value of the first navigation satellite navigation signal; inputting the first frequency bin initial value and the first pseudo code phase initial value into a first channel to search for the frequency bin and the pseudo code phase of the first navigation satellite navigation signal; receiving a second navigation satellite navigation signal; generating a second carrier estimated center frequency and a second pseudo code estimated phase according to the stored information of the missile-borne body before losing lock of the second navigation satellite navigation signal; generating a second simulated carrier signal locally to the missile-borne body according to the second carrier estimated center frequency and the second pseudo code estimated phase; performing correlation operation on the second navigation satellite navigation signal and the second simulated carrier signal to generate a second frequency bin initial value and a second pseudo code phase initial value of the second navigation satellite navigation signal; inputting the second frequency bin initial value and the second pseudo code phase initial value into a second channel to search for the frequency bin and the pseudo code phase of the second navigation satellite navigation signal; merging the search results of the first channel and the second channel to determine the frequency bin and the pseudo code phase of the navigation satellite navigation signal.

2. The method of claim 1, wherein, The generating of the first carrier estimated center frequency and the first pseudo code estimated phase according to the stored information of the missile-borne body before losing lock of the first navigation satellite navigation signal comprises: generating a Doppler shift value of the first carrier estimated center frequency and the first pseudo code estimated phase according to the motion information of the missile-borne body before losing lock of the first navigation satellite navigation signal; generating the first carrier estimated center frequency and the first pseudo code estimated phase according to the Doppler shift value.

3. The method of claim 2, wherein, The generating of the Doppler shift value of the first carrier estimated center frequency and the first pseudo code estimated phase according to the motion information of the missile-borne body before losing lock of the first navigation satellite navigation signal comprises: obtaining a motion speed V2 of the missile-borne body before losing lock of the first navigation satellite navigation signal from the stored information of the missile-borne body; obtaining a speed V1 of the navigation satellite before losing lock of the first navigation satellite navigation signal from the stored information of the missile-borne body; obtaining a vector e of the line-of-sight direction of the missile-borne body and the first navigation satellite from the stored information of the missile-borne body; according to the formula: ; A Doppler shift value of the first carrier estimated center frequency and the first pseudo code estimated phase is calculated, wherein The satellite navigation signal is in a carrier wavelength of the L band.

4. The method of claim 3, wherein, the generating of the first carrier estimated center frequency according to the Doppler shift value comprises: according to the formula: The first carrier pre-estimation center frequency value in the first accuracy range is calculated, wherein f L1 is the frequency of the satellite navigation signal in the L1 band, is the Doppler shift estimation value due to the movement of the carrier, f c is the local carrier frequency estimation value.

5. The method of claim 4, wherein, the generating of the first carrier estimated center frequency according to the Doppler shift value further comprises: At time N, find the highest frequency component in the navigation message transmitted by the 1 ms navigation satellite ; At N+T moment, which is T moment away from N moment, the frequency component in the preset intensity range in the navigation message sent by the navigation satellite is found ; The initial phase of the highest frequency component is calculated by the DFT algorithm :​ ； The initial phase of the frequency component is calculated by a DFT algorithm :​ ； from the initial phase of the highest frequency component from the initial phase of the highest frequency component from the initial phase of the highest frequency component from the initial phase of the highest frequency component calculating the fine frequency According to the formula: Here, f = fc, the first carrier estimated center frequency in the second accuracy range higher than the first accuracy range is calculated.

6. The method of claim 2, wherein, the generating of the first pseudo code estimated phase according to the Doppler shift value further comprises: obtaining a first carrier phase of the first navigation satellite before losing lock of the first navigation satellite navigation signal from the stored information of the missile-borne body; generating the first pseudo code estimated phase by referring to the Doppler shift value and the first carrier phase.

7. The method of claim 1, wherein, The receiving of the first navigation satellite navigation signal comprises: determining the first navigation satellite in a navigation satellite list; receiving the first navigation satellite navigation signal.

8. The method of claim 7, wherein, The determining of the first navigation satellite in the navigation satellite list comprises: Obtain missile-borne body position information, missile-borne body attitude information, ephemeris information of navigation satellites and antenna installation position information from the storage information of the missile-borne body; According to the missile-borne body position information, missile-borne body attitude information, ephemeris information of navigation satellites and antenna installation position information, a navigation satellite lock loss recapture list is screened from a navigation satellite list; In the navigation satellite lock loss recapture list, a first navigation satellite is determined.

9. A reacquisition apparatus for a loss of lock of a navigation satellite navigation signal by a receiver on board a vehicle, characterized in that, Comprise: A first receiving module for receiving a first navigation satellite navigation signal; A first estimation module for generating a first carrier estimated center frequency and a first pseudo-code estimated phase according to the storage information of the missile-borne body before the first navigation satellite navigation signal loses lock; A first processing module for generating a first simulated carrier signal of the missile-borne body according to the first carrier estimated center frequency and the first pseudo-code estimated phase; also for performing correlation operation on the first navigation satellite navigation signal and the first simulated carrier signal to generate a first frequency bin initial value and a first pseudo-code phase initial value of the first navigation satellite navigation signal; and further for inputting the first frequency bin initial value and the first pseudo-code phase initial value into a first channel to search for the frequency bin and the pseudo-code phase of the first navigation satellite navigation signal; A second receiving module for receiving a second navigation satellite navigation signal; A second estimation module for generating a second carrier estimated center frequency and a second pseudo-code estimated phase according to the storage information of the missile-borne body before the second navigation satellite navigation signal loses lock; A second processing module for generating a second simulated carrier signal of the missile-borne body according to the second carrier estimated center frequency and the second pseudo-code estimated phase; also for performing correlation operation on the second navigation satellite navigation signal and the second simulated carrier signal to generate a second frequency bin initial value and a second pseudo-code phase initial value of the second navigation satellite navigation signal; and further for inputting the second frequency bin initial value and the second pseudo-code phase initial value into a second channel to search for the frequency bin and the pseudo-code phase of the second navigation satellite navigation signal; A merging module for merging the search results of the first channel and the second channel to determine the frequency bin and the pseudo-code phase of the navigation satellite navigation signal.

10. The apparatus of claim 9, wherein, The first estimation module is specifically used for: Generating a Doppler shift value of the first carrier estimated center frequency and the first pseudo-code estimated phase according to the missile-borne body motion information before the first navigation satellite navigation signal loses lock; Generating the first carrier estimated center frequency and the first pseudo-code estimated phase according to the Doppler shift value.

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