Positioning system in case of carrier attitude changes

Abstract

The application discloses a positioning system under the condition of carrier posture change and severe situation, which comprises two-way receiving antennas, channel circuits, power supply circuits and external interface circuits. The positioning system adopts two-way receiving antennas which are respectively installed in the first quadrant and the third quadrant of the carrier, can ensure that the union of the two antennas receiving visible stars meets the navigation positioning requirements at any time, simultaneously uses the method of real-time storage and instantaneous analysis of intermediate frequency data to complete signal acquisition, and adopts data fusion technology to obtain GPS satellite pseudo-range according to external auxiliary pseudo-range, so as to realize the navigation positioning of the carrier.

Description

Technical Field

[0001] This invention relates to a navigation and positioning system, belonging to the field of satellite navigation and positioning, and is mainly used for navigation and positioning under adverse conditions of carrier attitude change. Background Technology

[0002] Under adverse conditions of carrier attitude change, the carrier motion may simultaneously involve large dynamics and rapid rotation along three axes with six degrees of freedom (not exceeding 720° / s). In such situations, the satellite signal received by the receiving device's antenna is intermittent and intermittent. Traditional satellite navigation receivers require satellite signal acquisition, tracking, pseudorange measurement, and navigation message demodulation to achieve navigation and positioning. To complete these tasks, the receiver needs to receive continuous and stable satellite signals. Therefore, traditional receivers cannot function properly under the aforementioned adverse attitude change conditions.

[0003] Conventional anti-rotation methods primarily employ diversity reception, including two-way diversity and four-way diversity. Both methods offer some degree of anti-rotation capability, but each has limitations in application. Two-way diversity uses two receiving antennas and is mainly used when the carrier occasionally flips but remains stable for extended periods, ensuring that at least one antenna can still receive satellite signals after a flip. Four-way diversity uses four receiving antennas, typically installed in the four quadrants of the carrier. It can withstand single-axis rotation of a certain speed under relatively low dynamic conditions, but it is not suitable for navigation and positioning under conditions of high dynamics or rapid three-axis rotation. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a positioning system under adverse conditions of carrier attitude change. The system adopts dual-antenna reception to ensure that the set of visible stars received by the two antennas at any time meets the navigation and positioning requirements. It completes signal acquisition by using a method of real-time storage and instantaneous analysis of intermediate frequency data, and obtains GPS satellite pseudorange by using data fusion technology based on external auxiliary pseudorange, thereby realizing navigation and positioning under adverse conditions of carrier attitude change.

[0005] The technical solution of the present invention is: a positioning system under adverse conditions of carrier attitude change, comprising two receiving antennas, a channel circuit, a channel circuit, a power supply circuit, and an external interface circuit;

[0006] Two receiving antennas are installed in the first and third quadrants of the carrier, respectively, and independently receive GPS satellite navigation radio frequency signals; the GPS satellite navigation radio frequency signals received by the two receiving antennas and the incoming channel circuit are processed;

[0007] The channel circuit includes two independent channel processing circuits, which process the two GPS satellite navigation radio frequency signals respectively to obtain orthogonal baseband signals; the orthogonal baseband signals output by the channel processing circuits enter the channel circuit for analog-to-digital conversion and baseband digital signal processing;

[0008] The channel circuit includes two A / D converters, an FPGA, and a CPU. The two A / D converters sample the quadrature baseband signal output from the channel processing circuit, convert it into a digital signal, and send it to the FPGA. Under the control of the CPU, the FPGA quickly acquires the input signal. The CPU uses the initial information obtained from the external auxiliary platform to obtain the pseudorange of GPS satellites by data fusion of the acquisition results and performs navigation calculations to obtain the navigation and positioning results of the vehicle. The navigation and positioning results of the vehicle are then transmitted to the FPGA, which outputs the navigation and positioning results of the vehicle to the external system through an external interface. The FPGA and the CPU communicate and exchange data through a data bus and an address bus.

[0009] The power supply circuit provides a stable and reliable power supply for the entire positioning system;

[0010] The interface circuit is mainly responsible for data communication with external systems.

[0011] The process by which the FPGA in the positioning system, under the control of the CPU, rapidly acquires the input signal is as follows:

[0012] (2.1) Under the control of the CPU, the FPGA acquires the digital signals output by the two A / D converters in real time and stores them in the FPGA's data RAM;

[0013] (2.2) The CPU uses the ephemeris and time information obtained from the external auxiliary platform to predict the currently visible GPS satellites and arranges the currently visible GPS satellites in descending order of elevation angle;

[0014] (2.3) The CPU selects the GPS satellite with the highest elevation angle based on the current visible GPS satellite elevation angle and controls the FPGA to generate the local reproduction pseudocode of the GPS satellite with the highest elevation angle.

[0015] (2.4) The CPU controls the FPGA to perform coherent and non-coherent accumulation operations on the digital signal acquired in step (2.1) and the local reproducible pseudocode generated in step (2.3) to obtain the coherent value and then obtain the correlation peak. The CPU reads the correlation peak and judges it. If the correlation peak exceeds the threshold, it is determined that the GPS satellite has been successfully captured. At the same time, the CPU records the capture result of the GPS satellite, that is, the pseudocode phase corresponding to the correlation peak. Otherwise, the capture fails.

[0016] (2.5) After the GPS satellite is captured, remove the captured GPS satellite from the list of satellites to be captured, and repeat steps (2.3), (2.4) and (2.5) until all visible satellites are captured.

[0017] The CPU utilizes initial information obtained from an external auxiliary platform to perform data fusion on the acquisition results to obtain the pseudorange of GPS satellites and performs navigation calculations to obtain the navigation and positioning results of the carrier. The implementation process is as follows:

[0018] (3.1) The CPU uses the ephemeris and time information obtained from the external auxiliary platform to obtain the spatial coordinates of the i-th GPS satellite at the current moment as x. i y i z i , i∈[1,n], where n is the number of satellites successfully captured by the FPGA under the control of the CPU, and the initial value of i is 1;

[0019] (3.2) Calculate the geometric distance ρ between the positioning system and the i-th GPS satellite. i The calculation formula is as follows:

[0020]

[0021] Where, ρ i The unit is meters; x i y i z i Let X be the spatial coordinates of the i-th GPS satellite obtained in step (3.1). s Y s Z s The coordinates of the positioning system are obtained from an external auxiliary platform, in meters.

[0022] (3.3) The geometric distance ρ between the positioning system and the i-th GPS satellite obtained in step (3.2) i The 1ms count value for the i-th GPS satellite is estimated using the following formula:

[0023]

[0024] in, Let c be the 1ms count value of the i-th GPS satellite, and c be the speed of light.

[0025] (3.4) Based on the 1ms count value obtained in step (3.3) The pseudo-code phase N of the i-th GPS satellite captured by the FPGA under the control of the CPU. ci The time when the i-th GPS satellite transmits its signal is calculated. The unit is milliseconds, and the calculation formula is:

[0026]

[0027] (3.5) Based on the local time T of the location system receiving the signal from the i-th GPS satellite recv and the time of satellite signal transmission of the i-th GPS satellite obtained in step (3.4) Calculate the pseudorange P of the i-th GPS satellite i The calculation formula is as follows:

[0028]

[0029] In the formula: P i Let P be the pseudorange of the i-th GPS satellite. i The unit is meters;

[0030] (3.6) The pseudorange P of the i-th GPS satellite obtained in step (3.5) i The correctness of the statement is determined based on the following criteria:

[0031] |ρ i -P i |<0.001*c

[0032] If the geometric distance ρ between the positioning system and the i-th GPS satellite calculated in step (3.2) is... i The pseudorange P of the i-th GPS satellite calculated in step (3.5) i If the criteria in step (3.6) are met, it means that the pseudorange of the GPS satellite is usable; otherwise, the pseudorange is invalid.

[0033] (3.7) Based on the above steps, obtain the pseudorange of all successfully captured GPS satellites and perform navigation calculations to obtain the navigation and positioning results of the positioning system, i.e., the carrier.

[0034] This invention can achieve rapid acquisition of normal signals, as well as rapid acquisition of weak signals.

[0035] The technical advantages of this invention compared to existing technologies are:

[0036] (1) The present invention stores intermediate frequency digital signals in real time, which can realize the rapid acquisition of signals under high dynamic and fast rotation weak signals;

[0037] (2) The present invention uses dual antenna reception to ensure that GPS satellite signals can still be effectively collected when the carrier attitude changes rapidly, thereby achieving positioning;

[0038] (3) Under the condition of severe changes in carrier attitude and without significant increase in hardware investment, the present invention can achieve rapid positioning in 1 second after power-on and output positioning results in real time at 1Hz. The navigation positioning accuracy is better than 1.5km, which meets the navigation positioning needs of landing rescue and search and rescue that require rapid and rough positioning. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structural composition of the positioning system of the present invention. Detailed Implementation

[0040] Navigation and positioning under adverse conditions of vehicle attitude change require navigation devices to achieve rapid positioning under conditions of high dynamics and rapid three-axis rotation of the vehicle. Traditional navigation and positioning receivers need to acquire, track, measure pseudorange, and demodulate navigation messages from satellite signals. However, they cannot guarantee continuous signal reception under adverse attitude changes, thus failing to perform these tasks. Common anti-rotation receiving techniques include diversity reception, but these are only suitable for slowly changing single-axis rotations.

[0041] This invention addresses navigation and positioning requirements under adverse conditions of carrier attitude changes. It employs a dual-antenna scheme, whose installation ensures that the combined set of visible satellite signals received by both antennas at any given time meets navigation and positioning requirements. The system uses real-time acquisition and storage of satellite intermediate frequency (IF) signals received by both antennas. Based on pre-set ephemeris and time data, it predicts currently visible satellites and sequentially generates local reproducible pseudo-codes for each visible satellite. It rapidly performs coherent and non-coherent accumulation operations between the stored IF signals and the local reproducible pseudo-codes to acquire the input signal. If the captured correlation peak exceeds a threshold, the pseudo-code phase corresponding to the correlation peak is recorded. After all visible satellites have been acquired, externally assisted coarse pseudoranges are used, and data fusion technology is employed to obtain the pseudoranges of all successfully acquired GPS satellites, thus achieving navigation and positioning of the carrier. The pseudorange accuracy obtained using this method typically reaches 1 / 2 chip, and for GPS systems, its accuracy is approximately 147m. A schematic diagram of the overall structure of this positioning system is shown below. Figure 1 As shown.

[0042] The positioning system for carrier attitude change under adverse conditions using the above scheme includes two receiving antennas 101 and 102, channel circuit 106, channel circuit 111, power supply circuit 118, and external interface circuit 117; at the same time, the positioning system also needs to obtain initial information and real-time auxiliary information 121 from the external auxiliary platform 120.

[0043] Two receiving antennas, 101 and 102, are respectively installed in the first and third quadrants of the carrier and independently receive GPS satellite navigation radio frequency signals. This installation method ensures that the combined set of visible stars received by both antennas at any given moment during the carrier's rapid rotation meets navigation and positioning requirements. The GPS satellite navigation radio frequency signals 103 and 104 received by the two receiving antennas 101 and 102 enter the channel circuit 106 for signal processing.

[0044] Channel circuit 106 includes two independent channel processing circuits 107 and 108, which process the two GPS satellite navigation radio frequency signals 103 and 104 respectively to obtain orthogonal baseband signals 109 and 110. The functions of channel processing circuits 107 and 108 are to perform signal filtering, amplification, and orthogonal down-conversion. The orthogonal baseband signals 109 and 110 output by channel processing circuits 107 and 108 enter channel circuit 111 for analog-to-digital conversion and baseband digital signal processing.

[0045] The channel circuit 111 includes two A / D converters 112 and 113, an FPGA 114, and a CPU 115. The two A / D converters 112 and 113 (each with two sampling channels) sample the quadrature baseband signals 109 and 110 output from the channel processing circuits 107 and 108, respectively, converting them into digital signals which are then fed into the FPGA 114. Under the control of the CPU 115, the FPGA 114 performs real-time storage, rapid acquisition, and external interface functions for the intermediate frequency sampled digital signals, and sends the relevant results to the CPU 115. Based on the acquisition results, the CPU 115 utilizes initial information obtained from the external auxiliary platform 120, including satellite information, time, initial position, velocity, and real-time auxiliary information, to perform pseudorange calculation and navigation solution by data fusion of the acquisition results, and outputs the navigation and positioning result 119 through the external interface 117. FPGA 114 and CPU 115 communicate and exchange data via data bus and address bus 116.

[0046] In addition, the power module 118 is responsible for providing various voltages to the entire receiving device, such as 5V, 3.3V, and 1.2V, and provides power filtering design, transient suppression design, reverse connection protection design, and short-circuit protection design to provide a stable and reliable power supply for the entire receiving device and improve power utilization efficiency. The interface circuit 117 includes a system interface circuit and a test interface circuit. Both the system interface circuit and the test interface circuit adopt a standard RS-422 interface circuit design, mainly responsible for data communication with external systems and monitoring systems.

[0047] Meanwhile, to achieve rapid positioning, the receiver needs to obtain relevant information from an external auxiliary platform, mainly including initial information and real-time auxiliary information. Initial information primarily includes the latest satellite ephemeris, initial time, position, and velocity. Real-time auxiliary information includes the real-time transmission of the carrier's approximate position and velocity to the receiving device. This information can be relatively coarse, for example, with a position accuracy requirement within 50km, and can be output using low-cost MEMS. This information is mainly used to predict currently visible satellites and eliminate ambiguities in the acquired pseudorange.

[0048] The key to this invention is that, under adverse attitude change conditions, stable tracking of GPS satellite signals is not required. Instead, pseudo-code phase of GPS satellites is acquired by real-time acquisition of intermediate frequency data, and relatively accurate pseudorange measurement is achieved using external auxiliary conditions, thus obtaining more accurate navigation and positioning. Therefore, the two key technologies of this invention are:

[0049] (1) Rapid capture technology under conditions of high dynamics and rapid three-axis rotation;

[0050] (2) Data fusion technology under the condition of external information assistance.

[0051] One of the key technologies, rapid acquisition under conditions of high dynamic range and rapid three-axis rotation, requires quickly acquiring all visible GPS satellites simultaneously and calculating pseudorange under the aforementioned harsh navigation and positioning conditions. Traditional receivers acquire GPS satellite signals, correlate them with local reproducible codes, and track them. Once a GPS satellite signal is tracked, the phase of the local reproducible code matches the code phase in the GPS satellite signal. By collecting information such as the code count of the local channel reproducible codes of all visible satellites at the same time, the transmission time of the received GPS satellite signal at the sampling time is obtained. Pseudorange is then calculated using correlation algorithms, and navigation is achieved using GPS satellite ephemeris data. However, due to the high dynamic range and rapid three-axis rotation of the carrier, the receiving antenna cannot receive stable satellite signals, and the receiver cannot complete normal acquisition and tracking. Furthermore, traditional tracking loops cannot withstand such high dynamic range, thus failing to meet the application requirements under these conditions.

[0052] To address this problem, this invention employs dual-antenna reception and utilizes a real-time data acquisition and instantaneous analysis method to quickly acquire all visible GPS satellites at the acquisition time and determine the pseudo-code phase of all visible GPS satellites at the same transmission time. The key to this technology lies in the real-time storage of a large amount of acquired intermediate frequency (IF) data and the use of this stored IF data to achieve rapid signal acquisition.

[0053] Large-scale FPGAs possess abundant on-chip resources, including embedded RAM, hardware multipliers, and various programmable logic units. The large amount of real-time intermediate frequency data acquired can be stored using the FPGA's embedded RAM. Rapid signal acquisition is achieved by the FPGA in the positioning system under the control of the CPU. The specific implementation process is as follows:

[0054] (2.1) Under the control of the CPU, the FPGA acquires the digital signals output by the two A / D converters 112 and 113 in real time and stores them in the data RAM of the FPGA 114;

[0055] (2.2) The CPU uses the ephemeris and time information obtained from the external auxiliary platform 120 to predict the currently visible GPS satellites and arranges the currently visible GPS satellites from high to low elevation angle;

[0056] (2.3) The CPU selects the GPS satellite with the highest elevation angle based on the current visible GPS satellite elevation angle and controls the FPGA to generate the local reproduction pseudocode of the GPS satellite with the highest elevation angle.

[0057] (2.4) The CPU controls the FPGA to perform coherent and non-coherent accumulation operations on the digital signal acquired in step (2.1) and the local reproducible pseudocode generated in step (2.3) to obtain the coherent value and then obtain the correlation peak. The CPU reads the correlation peak and judges it. If the correlation peak exceeds the threshold, it is determined that the GPS satellite has been successfully captured. At the same time, the CPU records the capture result of the GPS satellite, that is, the pseudocode phase corresponding to the correlation peak. Otherwise, the capture fails.

[0058] (2.5) After the GPS satellite is captured, remove the captured GPS satellite from the list of satellites to be captured, and repeat steps (2.3), (2.4) and (2.5) until all visible satellites are captured.

[0059] This allows for the acquisition of signals from all visible GPS satellites using intermediate frequency (IF) data collected simultaneously, obtaining the pseudo-code phase of all visible GPS satellites at the same sampling time. Typically, the chip step size during acquisition is approximately 1 / 2 chip, so theoretically, the acquisition chip accuracy is about 1 / 4 chip. Considering the impact of acquisition noise, the actual acquisition pseudo-code accuracy may be 1 / 2 chip.

[0060] This invention employs coherent and non-coherent accumulation operations, enabling rapid acquisition of normal signals as well as rapid acquisition of weak signals (-143dBm).

[0061] For receiver sensitivity (including low noise) in weak signal environments, assuming the GPS satellite signal level is -143dBm, the equivalent signal-to-noise ratio of the digital part after AD sampling is:

[0062] SNR=-143-(-174+10log(B))=-32dB

[0063] Where -174dBHz represents the ambient thermal noise, and B is the signal bandwidth, which is 2.046MHz for GPS signals. To obtain a noticeable correlation peak, the signal-to-noise ratio (SNR) after signal processing should typically reach 10dB. Therefore, signal processing, through coherent and incoherent integration, requires a gain of 10 - (-32) = 42dB.

[0064] Assuming a coherence time of 1 ms, an equivalent noise bandwidth of 1 kHz, and a corresponding noise floor of -144 dBm, the equivalent output SNR after 1 ms of coherence is -143 - (-144) = 1 dB. To achieve an output SNR of 10 dB, the incoherent integration needs to provide a gain of 10 - 1 = 9 dB. Typically, the incoherent integration gain is only 5 log(m) due to the squared loss, where m is the number of incoherent iterations. When m is 64, the required sensitivity can be achieved after 1 ms of coherence and 64 incoherent iterations.

[0065] Another key technology, data fusion technology under external pseudorange assistance, mainly studies how to use the captured pseudocode phase, the approximate position and velocity of the carrier provided by the external assistance platform, and the orbital characteristics of GPS satellites to generate pseudorange that can be used for navigation calculation.

[0066] In this invention, GPS satellite navigation and positioning adopts the ranging principle. Generally, the positioning system internally calculates the pseudorange of the GPS satellites involved in the positioning based on the following formula:

[0067] The general equation for calculating pseudorange is:

[0068] P = (T) revc -T tras )*c (1)

[0069] Where P is the measurement pseudorange, in meters; c is the speed of light, in meters per second; T recv T is the local time for the positioning system to receive GPS satellite signals. tras The satellite time for transmitting satellite signals to GPS satellites, in seconds.

[0070] Formula (1) represents the distance from the satellite to the positioning system. Multiplying the propagation delay of the satellite signal to the positioning system by the signal propagation speed allows calculation of the distance between the satellite and the positioning system. The local time T at which the positioning system receives the GPS satellite signal is... recv The satellite time T for GPS satellite signal transmission can be directly calculated using the positioning system's time. trasBecause the positioning system cannot guarantee the continuity of signal reception during severe attitude changes, it cannot provide a 1ms count and cannot use traditional acquisition and tracking to achieve the navigation and positioning of the carrier. In order to realize the positioning function of the positioning system, it is necessary to use the approximate position and velocity of the carrier provided by the external auxiliary platform, combined with the orbital characteristics of the GPS satellites, to estimate the 1ms count. Then, based on the captured pseudocode phase count, the time when each GPS satellite participating in navigation and positioning transmits satellite signals is obtained. Finally, the required pseudorange is calculated according to formula (1). The following are the methods and basic steps for calculating the pseudorange of GPS satellites:

[0071] (3.1) The CPU uses the ephemeris and time information obtained from the external auxiliary platform 120 to obtain the spatial coordinates of the i-th GPS satellite at the current moment as x. i y i z i , i∈[1,n], where n is the number of satellites successfully captured by the FPGA under the control of the CPU, and the initial value of i is 1;

[0072] (3.2) Calculate the geometric distance ρ between the positioning system and the i-th GPS satellite. i The calculation formula is as follows:

[0073]

[0074] Where, ρ i The unit is meters; x i y i z i Let X be the spatial coordinates of the i-th GPS satellite obtained in step (3.1). s Y s Z s The coordinates of the positioning system are obtained from the external auxiliary platform 120, in meters;

[0075] (3.3) The geometric distance ρ between the positioning system and the i-th GPS satellite obtained in step (3.2) i The 1ms count value for the i-th GPS satellite is estimated using the following formula:

[0076]

[0077] in, Let c be the 1ms count value of the i-th GPS satellite, and c be the speed of light.

[0078] (3.4) Based on the 1ms count value obtained in step (3.3) The pseudo-code phase N of the i-th GPS satellite captured by the FPGA under the control of the CPU. ciThe time when the i-th GPS satellite transmits its signal is calculated. The unit is milliseconds, and the calculation formula is:

[0079]

[0080] (3.5) Based on the local time T of the location system receiving the signal from the i-th GPS satellite recv and the time of satellite signal transmission of the i-th GPS satellite obtained in step (3.4) Calculate the pseudorange P of the i-th GPS satellite i The calculation formula is as follows:

[0081]

[0082] In the formula: P i Let P be the pseudorange of the i-th GPS satellite. i The unit is meters;

[0083] (3.6) The pseudorange P of the i-th GPS satellite obtained in step (3.5) i The correctness of the statement is determined based on the following criteria:

[0084] |ρ i -P i |<0.001*c (6)

[0085] If the geometric distance ρ between the positioning system and the i-th GPS satellite calculated in step (3.2) is... i The pseudorange P of the i-th GPS satellite calculated in step (3.5) i If the criteria in step (3.6) are met, it means that the pseudorange of the GPS satellite is usable; otherwise, the pseudorange is invalid.

[0086] (3.7) Based on the above steps, obtain the pseudorange of all successfully captured GPS satellites and perform navigation calculations to obtain the navigation and positioning results of the positioning system, i.e., the carrier.

[0087] With the acquisition of initial information such as GPS satellite ephemeris and time, and external assistance, this invention can achieve positioning within 1 second of power-on and output positioning results at 1Hz in real time, with a positioning accuracy better than 1.5km (1σ).

[0088] The contents not described in detail in the specification are common knowledge to those skilled in the art.

Claims

1. A positioning system for use under adverse conditions of carrier attitude change, characterized in that: It includes two receiving antennas, channel circuit (106), channel circuit (111), power supply circuit (118), and external interface circuit (117); Two receiving antennas are installed in the first and third quadrants of the carrier, respectively, and independently receive GPS satellite navigation radio frequency signals; the GPS satellite navigation radio frequency signals received by the two receiving antennas enter the channel circuit (106) for signal processing; The channel circuit (106) includes two independent channel processing circuits, which process the two GPS satellite navigation radio frequency signals respectively to obtain two orthogonal baseband signals; the two orthogonal baseband signals output by the channel processing circuit enter the channel circuit (111) for analog-to-digital conversion and baseband digital signal processing; The channel circuit (111) includes two A / D converters, an FPGA (114), and a CPU (115). The two A / D converters sample the two quadrature baseband signals respectively, convert the quadrature baseband signals into digital signals, and send them to the FPGA (114). Under the control of the CPU (115), the FPGA (114) realizes the rapid acquisition of the input signals. The CPU (115) uses the initial information obtained from the external auxiliary platform (120), performs data fusion on the acquisition results to obtain the pseudorange of the GPS satellites, performs navigation calculation, obtains the navigation and positioning results of the carrier, and transmits the navigation and positioning results of the carrier to the FPGA (114). The FPGA (114) outputs the navigation and positioning results (119) of the carrier to the external system through the external interface (117). The FPGA (114) and the CPU (115) communicate and exchange data through the data bus and the address bus (116). The power supply circuit (118) provides a stable and reliable power supply for the entire positioning system; The interface circuit (117) is mainly responsible for data communication with external systems.

2. The positioning system for carrier attitude changes under adverse conditions according to claim 1, characterized in that: The process by which the FPGA (114) in the positioning system, under the control of the CPU (115), rapidly acquires the input signal is as follows: (2.1) Under the control of the CPU (115), the FPGA (114) collects the digital signals output by the two A / D converters in real time and stores them in the data RAM of the FPGA (114); (2.2) The CPU (115) uses the ephemeris and time information obtained from the external auxiliary platform (120) to predict the currently visible GPS satellites and arrange the currently visible GPS satellites in descending order of elevation angle; (2.3) The CPU (115) selects the GPS satellite with the highest elevation angle based on the elevation angle of the currently visible GPS satellites and controls the FPGA (114) to generate the local reproduction pseudocode of the GPS satellite with the highest elevation angle. (2.4) The CPU (115) controls the FPGA (114) to perform coherent accumulation operation on the digital signal acquired in step (2.1) and the local reproducible pseudocode generated in step (2.3), and then perform incoherent accumulation operation to obtain the coherent value and then obtain the correlation peak. The CPU (115) reads the correlation peak and judges the correlation peak. If the correlation peak exceeds the threshold, it is determined that the GPS satellite has been successfully captured. At the same time, the CPU (115) records the capture result of the GPS satellite, that is, the pseudocode phase corresponding to the correlation peak. Otherwise, the capture fails. (2.5) After the GPS satellite is captured, remove the captured GPS satellite from the list of satellites to be captured, and repeat steps (2.3) and (2.4) until all visible satellites are captured.

3. The positioning system for adverse carrier attitude changes according to claim 2, characterized in that: The CPU (115) uses the initial information obtained from the external auxiliary platform (120), performs data fusion on the acquisition results to obtain the pseudorange of GPS satellites, and performs navigation calculations to obtain the navigation and positioning results of the carrier. The implementation process is as follows: (3.1) The CPU (115) uses the ephemeris and time information obtained from the external auxiliary platform (120) to obtain the spatial position coordinates of the i-th GPS satellite at the current time as x. i y i z i , i∈[1,n], where n is the number of satellites successfully captured in claim 2, and the initial value of i is 1; (3.2) Calculate the geometric distance ρ between the positioning system and the i-th GPS satellite. i The calculation formula is as follows: Where, ρ i The unit is meters; x i y i z i Let X be the spatial coordinates of the i-th GPS satellite obtained in step (3.1). s Y s Z s The position coordinates of the positioning system obtained from the external auxiliary platform (120) are in meters; (3.3) The geometric distance ρ between the positioning system and the i-th GPS satellite obtained in step (3.2) i The 1ms count value for the i-th GPS satellite is estimated using the following formula: in, Let c be the 1ms count value of the i-th GPS satellite, and c be the speed of light. (3.4) Based on the 1ms count value obtained in step (3.3) The pseudocode phase N of the i-th GPS satellite captured in claim 2 ci Calculate the time when the i-th GPS satellite transmits navigation radio frequency signals. The unit is milliseconds, and the calculation formula is: (3.5) Based on the local time T of the GPS navigation radio frequency signal received by the positioning system from the i-th GPS satellite recv and the time of the navigation radio frequency signal transmitted by the i-th GPS satellite obtained in step (3.4) Calculate the pseudorange P of the i-th GPS satellite i The calculation formula is as follows: In the formula: P i Let P be the pseudorange of the i-th GPS satellite. i The unit is meters; (3.6) The pseudorange P of the i-th GPS satellite obtained in step (3.5) i The correctness of the statement is determined based on the following criteria: |ρ i -P i |90.001*c If the geometric distance ρ between the positioning system and the i-th GPS satellite calculated in step (3.2) is... i The pseudorange P of the i-th GPS satellite calculated in step (3.5) i If the criteria in step (3.6) are met, it means that the pseudorange of the GPS satellite is usable; otherwise, the pseudorange is invalid. (3.7) Based on the above steps, obtain the pseudorange of all successfully captured GPS satellites and perform navigation calculations to obtain the navigation and positioning results of the positioning system, i.e., the carrier.

4. The positioning system for adverse carrier attitude changes according to claim 1, characterized in that: The positioning system can quickly capture normal signals, as well as quickly capture weak signals.

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