Space-based GPS M code signal power monitoring method and system

Abstract

The invention provides a space-based GPS M code signal power monitoring method and system, and the method comprises the steps: receiving a GPS signal, and outputting a digital signal; adopting a band-pass filtering mode to extract a GPS M code digital signal; reading dynamic information data of a low-orbit satellite platform and dynamic information data of a GPS satellite; estimating GPS M code signal delay and Doppler; estimating the carrier phase of the GPS M code signal; generating a GPS M code signal local carrier; multiplying the generated GPS M code signal local carrier by the GPS M code digital signal extracted by filtering to complete GPS M code signal carrier demodulation; carrying out pseudo code elimination on the GPS M code signal; the signal-to-noise ratio of the signal component is improved through coherent integration; and estimating the power of the GPS M code signal. The method has the advantages that the defect that a traditional foundation monitoring GPS M code signal power means cannot monitor GPS M code signal spot beam power enhancement is overcome.

Description

Technical Field

[0001] The present application relates to the fields of satellite navigation and aerospace electronic reconnaissance, and specifically to a method and system for space-based monitoring of GPS and M-code signal power. Background Art

[0002] The Global Navigation Satellite System (GNSS) has significantly promoted economic and social development, advanced scientific research, and transformed people's lifestyles. With its rapid development and widespread application, users, both in civilian and military fields, have placed higher demands on GNSS performance. Against this backdrop, the United States has proposed a Global Positioning System (GPS) modernization plan, which aims to replace the existing GPS IIR and GPS IIF satellites with the next-generation GPS IIIA and GPS IIIF satellites.

[0003] GPS IIIA and GPS IIIF satellites will independently broadcast M-code signals on the L1 frequency band (1575.42 MHz) and the L2 frequency band (1227.60 MHz). The M-code signal is one of the authorized signals broadcast by GPS and will become the mainstream authorized signal for GPS, serving authorized users approved by the United States. Furthermore, GPS IIIF satellites will feature an M-code signal spot beam power boost capability, significantly increasing the M-code signal transmission power within a specific area of ​​approximately 1,000 kilometers. This ensures that authorized users' GPS terminals in this area can function normally and effectively even under strong GPS interference conditions.

[0004] As we all know, monitoring GPS M-code signal power has extremely important practical significance and application value. Currently, existing ground-based methods for monitoring GPS M-code signal power in China are only effective when GPS M-code signal power is globally enhanced. As mentioned earlier, future mainstream GPS IIIF satellites will feature M-code signal spot beam power enhancement capabilities, rendering traditional ground-based methods for monitoring GPS M-code signal power ineffective in China. Therefore, it is necessary to develop space-based methods and systems for monitoring GPS M-code signal power to enable enhanced GPS M-code signal spot beam power monitoring.

[0005] In summary, space-based monitoring of GPS M-code signal power can not only achieve global enhanced monitoring of GPS M-code signal power, but also achieve enhanced monitoring of GPS M-code signal spot beam power. It has very important practical significance and application value, and has become one of the hot topics in the fields of satellite navigation and aerospace electronic reconnaissance. Summary of the Invention

[0006] The purpose of this application is to propose a method and system for space-based monitoring of GPS M-code signal power. This method and system, as an effective solution, can be applied to low-orbit satellite platforms and can not only achieve global enhanced monitoring of GPS M-code signal power, but also enhance monitoring of GPS M-code signal spot beam power.

[0007] To achieve the above objectives, this application proposes a space-based method for monitoring GPS M-code signal power, comprising:

[0008] Step S101: receiving GPS signals;

[0009] Step S102: The received GPS signal is sequentially subjected to low-noise amplification, filtering, down-conversion, re-filtering, re-amplification, sampling and quantization, and finally output as a GPS digital signal;

[0010] Step S103: extracting the GPS M-code digital signal from the GPS digital signal using a bandpass filter;

[0011] Step S104: Reading low-orbit satellite platform dynamic information data;

[0012] Step S105: Read GPS satellite dynamic information data;

[0013] Step S106: Estimate GPS M-code signal delay and Doppler;

[0014] Step S107: estimating the carrier phase of the GPS M-code signal based on the estimated delay and Doppler of the GPS M-code signal;

[0015] Step S108: Generate a GPS M-code signal local carrier based on the carrier phase of the GPS M-code signal;

[0016] Step S109: multiplying the generated GPS M-code signal local carrier with the GPS M-code digital signal extracted by filtering to complete GPS M-code signal carrier demodulation;

[0017] Step S110: performing pseudo code elimination on the GPS M code signal;

[0018] Step S111: improving the signal-to-noise ratio of the signal component obtained after the GPS M-code signal pseudo-code is eliminated through coherent integration;

[0019] Step S112: Estimate the GPS M-code signal power.

[0020] As an improvement to the above method, in step S104 , dynamic information data of the low-orbit satellite platform is read, including the real-time position and real-time speed of the low-orbit satellite platform.

[0021] As an improvement to the above method, in step S105 , GPS satellite dynamic information data is read, including the real-time position and real-time speed of the GPS satellite.

[0022] As an improvement to the above method, the GPS M-code signal delay and Doppler in step S106 are expressed as:

[0023]

[0024] Among them, τ i (n) and d i (n) represents the delay and Doppler of the GPS M-code signal broadcast by the i-th GPS satellite reaching the low-orbit satellite platform; c represents the speed of light in vacuum; f L Indicates the carrier center frequency corresponding to the center frequency point of the current GPS M code signal; P L (n) represents the real-time position of the low-orbit satellite platform; P G,i (n) represents the real-time position of the i-th GPS satellite; V L (n) represents the real-time speed of the low-orbit satellite platform; V G,i (n) represents the real-time velocity of the i-th GPS satellite; ||·|| represents the modulus of the orientation quantity.

[0025] As an improvement to the above method, in step S107, the carrier phase of the GPS M-code signal broadcast by the i-th GPS satellite arriving at the low-orbit satellite platform is expressed as:

[0026]

[0027] in, represents the carrier phase of the GPS M-code signal broadcast by the i-th GPS satellite arriving at the low-orbit satellite platform; f L Indicates the carrier center frequency corresponding to the center frequency point of the current GPS M code signal; n represents the nth signal data obtained by sampling; T s represents the sampling interval; τ i (n) and d i (n) represents the delay and Doppler of the GPS M-code signal broadcast by the i-th GPS satellite reaching the low-orbit satellite platform.

[0028] As an improvement to the above method, in step S108, the local carrier of the generated GPS M-code signal is represented as:

[0029]

[0030] Among them, Car i(n) represents the local carrier of the GPS M-code signal generated by the i-th GPS satellite; j represents the imaginary unit; It represents the carrier phase of the GPS M-code signal broadcast by the i-th GPS satellite arriving at the low-orbit satellite platform.

[0031] As an improvement to the above method, in step S110, the GPSM code signal pseudo code is eliminated using the square method, which is expressed as:

[0032] C M,i (n)=[D M,i (n)] 2

[0033] Among them, C M,i (n) represents the result after the pseudo code of the GPS M code signal broadcast by the i-th GPS satellite is eliminated; D M,i (n) represents the result of carrier demodulation of the GPSM code signal broadcast by the i-th GPS satellite.

[0034] As an improvement to the above method, the coherent integration in step S111 is expressed as:

[0035]

[0036] Where N represents the number of data accumulated in the coherent integration operation; k represents the kth coherent integration operation; R M,i (k) represents the kth coherent integration result; C M,i (n) represents the result after the pseudo code of the GPS M-code signal broadcast by the i-th GPS satellite is eliminated.

[0037] As an improvement to the above method, in step S112, the GPS M-code signal power estimation method is:

[0038] P M,i (k) = G M (Tp(k))·R M,i (k)

[0039] Among them, G M (Tp(k)) represents the total gain of the space-based monitoring GPS M-code signal power system; Tp(k) represents the temperature of the RF front end of the space-based monitoring GPS M-code signal power system measured in real time; P M,i (k) represents the estimated GPS M-code signal power broadcast by the i-th GPS satellite; R M,i (k) represents the k-th coherent integration result.

[0040] The present application also provides a system for space-based monitoring of GPS M-code signal power, which is implemented based on the above method, and the system includes:

[0041] GPS signal receiving module, used for receiving GPS signals;

[0042] The GPS digital signal acquisition module is used to perform low-noise amplification, filtering, down-conversion, re-filtering, re-amplification, sampling and quantization on the received GPS signal, and finally output the GPS digital signal;

[0043] A GPSM code digital signal extraction module is used to extract the GPSM code digital signal from the GPS digital signal by using a bandpass filtering method;

[0044] The low-orbit satellite platform data reading module is used to read the dynamic information data of the low-orbit satellite platform;

[0045] GPS satellite data reading module, used to read GPS satellite dynamic information data;

[0046] Delay and Doppler estimation module, used to estimate GPSM code signal delay and Doppler;

[0047] The carrier phase estimation module is used to estimate the carrier phase of the GPS M code signal according to the estimated delay and Doppler of the GPS M code signal;

[0048] A local carrier generation module is used to generate a local carrier of the GPSM code signal based on the carrier phase of the GPSM code signal;

[0049] The carrier demodulation module is used to multiply the generated GPSM code signal local carrier with the GPSM code digital signal extracted by filtering to complete the GPSM code signal carrier demodulation;

[0050] Pseudo-code elimination module, used to eliminate pseudo-code of GPSM code signal;

[0051] A signal-to-noise ratio improving module is used to improve the signal-to-noise ratio of the signal component obtained after the GPSM code signal pseudo code is eliminated through coherent integration;

[0052] The signal power estimation module is used to estimate the GPSM code signal power.

[0053] Compared with the prior art, the advantages of this application are:

[0054] 1. The method and system proposed in the present invention are applicable to low-orbit satellite platforms. They can not only realize global enhanced monitoring of GPS M-code signal power, but also realize enhanced monitoring of GPS M-code signal spot beam power. This overcomes the deficiency of traditional ground-based monitoring methods of GPS M-code signal power that cannot monitor GPS M-code signal spot beam power enhancement.

[0055] 2. The method proposed in the present invention is simple, effective and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 Shown is a flow chart of a method for space-based monitoring of GPS M-code signal power;

[0057] Figure 2 Figure 2 is a schematic diagram of a space-based monitoring system for GPS M-code signal power. DETAILED DESCRIPTION

[0058] The technical solution of this application is described in detail below with reference to the accompanying drawings.

[0059] like Figure 1 As shown, the present invention proposes a space-based method for monitoring GPS M-code signal power, comprising:

[0060] Step S101) Receive GPS signals.

[0061] To monitor the GPS M-code signal power, the GPS signal must first be received, then processed, and finally the GPS M-code signal power estimated. To improve the signal-to-noise ratio (SNR) of the received signal, a right-hand circularly polarized receiving antenna with high gain is typically used to receive the GPS signal. The received GPS signal can be expressed as:

[0062]

[0063] Where t represents time; I represents the total number of GPS satellites within the field of view; i represents the i-th GPS satellite within the field of view; S(t) represents the received GPS signal; S M (t) represents the GPS M-code signal to be monitored; S X (t) represents the sum of all signals except the GPS M-code signal to be monitored; S M,i (t) represents the GPS M-code signal expected to be monitored and broadcast by the i-th GPS satellite; S X,i (t) represents the sum of all signals broadcast by the i-th GPS satellite except the GPS M-code signal to be monitored; η(t) represents the received thermal noise.

[0064] Step S102) The RF front end outputs a GPS digital signal.

[0065] Generally, the RF front end performs low-noise amplification, filtering, down-conversion, re-filtering, amplification, sampling, and quantization on the GPS signal received by the receiving antenna, and finally outputs the GPS digital signal. The GPS digital signal output by the RF front end can be expressed as:

[0066]

[0067] Where n represents the nth signal data obtained by sampling, and corresponds to the sampling time nT s (T s represents the sampling interval and satisfies the sampling law requirements).

[0068] Step S103) Filter and extract the GPS M-code digital signal.

[0069] Because the GPS M-code signal uses Binary Offset Carrier (BOC) modulation, specifically BOC(10,5), its power spectrum is split to either side of the center frequency and separate from the power spectrum of other GPS signals. Therefore, bandpass filtering can be used to extract the GPS M-code digital signal from the GPS digital signal output by the RF front-end.

[0070] In summary, the GPS M-code digital signal extracted by filtering can be expressed as:

[0071] F M (n)=BPF{S(n)} (3)

[0072] Where BPF{·} represents the bandpass filtering operation; F M (n) represents the GPS M-code digital signal extracted by filtering.

[0073] Step S104) Reading low-orbit satellite platform dynamic information data.

[0074] Low-orbit satellite platforms are generally equipped with onboard GNSS receivers, which are used to calculate the position, velocity, and time (PVT) information of the low-orbit satellite platform in real time and can be read in real time. The dynamic information data of the low-orbit satellite platform includes: (1) the real-time position of the low-orbit satellite platform, denoted as P L (n); (2) Real-time speed of the low-orbit satellite platform, denoted as V L (n). Based on the Earth-Centered Earth-Fixed (ECEF) coordinate frame, the dynamic information of these low-orbit satellite platforms can be expressed as:

[0075]

[0076] Among them, X L (n), Y L (n), Z L (n) represents the projection of the real-time position of the low-orbit satellite platform on the X-axis, Y-axis, and Z-axis in the ECEF coordinate frame; V X,L (n), V Y,L (n), VZ,L (n) represents the projection of the real-time velocity of the low-orbit satellite platform on the X-axis, Y-axis, and Z-axis in the ECEF coordinate frame; the superscript T indicates transposition.

[0077] Step S105) Read GPS satellite dynamic information data.

[0078] Low-orbit satellite platforms are generally equipped with onboard GNSS receivers. By receiving and processing GPS signals in real time, they can calculate the position and velocity information of GPS satellites in real time. The dynamic information data of the i-th GPS satellite includes: (1) the real-time position of the i-th GPS satellite, denoted as P G,i (n); (2) Real-time speed of the i-th GPS satellite, denoted as V G,i (n). Based on the ECEF coordinate framework, the dynamic information of the i-th GPS satellite can be expressed as:

[0079]

[0080] Among them, X G,i (n), Y G,i (n), Z G,i (n) represents the projection of the real-time position of the GPS satellite on the X-axis, Y-axis, and Z-axis in the ECEF coordinate frame; V X,G,i (n), V Y,G,i (n), V Z,G,i (n) represents the projection of the real-time velocity of the GPS satellite on the X-axis, Y-axis, and Z-axis in the ECEF coordinate frame.

[0081] Step S106) Estimate GPS M-code signal delay and Doppler.

[0082] Based on the dynamic information data of the low-orbit satellite platform and the dynamic information data of the GPS satellite, the delay and Doppler of the GPS M-code signal are directly estimated. The delay and Doppler of the GPS M-code signal broadcast by the i-th GPS satellite reaching the low-orbit satellite platform are expressed as:

[0083]

[0084] Among them, τ i (n) and d i (n) represents the delay and Doppler of the GPS M-code signal broadcast by the i-th GPS satellite reaching the low-orbit satellite platform; c represents the speed of light in vacuum; f L Indicates the carrier center frequency corresponding to the center frequency point of the current GPS M-code signal; ||·|| indicates the modulus of the orientation quantity.

[0085] Step S107) Restore the GPS M-code signal carrier phase.

[0086] Based on the estimated delay and Doppler of the GPS M-code signal, the carrier phase of the GPS M-code signal is directly estimated. The carrier phase of the GPS M-code signal broadcast by the i-th GPS satellite when it reaches the low-orbit satellite platform is expressed as:

[0087]

[0088] in, It represents the carrier phase of the GPS M-code signal broadcast by the i-th GPS satellite arriving at the low-orbit satellite platform.

[0089] Step S108) Generate GPS M-code signal local carrier.

[0090] Based on the recovered GPS M-code signal carrier phase, the GPS M-code signal local carrier can be generated. For the GPS M-code signal broadcast by the i-th GPS satellite, the generated local carrier is expressed as:

[0091]

[0092] Among them, Car i (n) represents the local carrier of the GPS M-code signal generated by the i-th GPS satellite; j represents the imaginary unit, and exp(·) represents the e-exponential function.

[0093] Step S109) GPS M-code signal carrier demodulation.

[0094] The generated GPS M-code signal local carrier is multiplied by the filtered extracted GPS M-code digital signal to complete the GPS M-code signal carrier demodulation. Carrier demodulation of the GPS M-code signal broadcast by the i-th GPS satellite can be expressed as:

[0095] D M,i (n) = F M (n) Car i (n) (9)

[0096] Among them, D M,i (n) represents the result of carrier demodulation of the GPS M-code signal broadcast by the i-th GPS satellite.

[0097] Step S110) GPS M-code signal pseudo code elimination.

[0098] Because the GPS M-code signal is an authorized signal, the pseudo-code signal modulated on the GPS M-code signal is unknown, so it is impossible to eliminate the pseudo-code by locally generating a replica code. In summary, the present invention uses the "square" method to eliminate the pseudo-code of the GPS M-code signal, which is expressed as:

[0099] CM,i (n)=[D M,i (n)] 2 (10)

[0100] Among them, C M,i (n) represents the result after the pseudo code of the GPS M-code signal broadcast by the i-th GPS satellite is eliminated.

[0101] Step S111) Coherent integration.

[0102] Because the GPS M-code signal's pseudo-code cancellation is performed using the "squaring" method, the process of pseudo-code cancellation results in an increase in noise power. By performing long-term coherent integration, the signal-to-noise ratio of the signal component obtained after the GPS M-code signal's pseudo-code cancellation can be improved. The coherent integration operation is expressed as:

[0103]

[0104] Where N represents the number of data accumulated in the coherent integration operation; k represents the kth coherent integration operation; R M,i (k) represents the k-th coherent integration result.

[0105] Step S112) GPS M-code signal power estimation.

[0106] Based on the coherent integration results, the GPS M-code signal power broadcast by the i-th GPS satellite can be estimated. The GPS M-code signal power estimation method is:

[0107]

[0108] Among them, G M represents the total gain of the space-based monitoring GPS M-code signal power system, which can be measured by ground calibration; Tp represents the temperature of the RF front end of the space-based monitoring GPS M-code signal power system measured in real time; P M,i (k) represents the estimated GPS M-code signal power broadcast by the i-th GPS satellite.

[0109] The present application also provides a system for space-based monitoring of GPS M-code signal power, which is implemented based on the above method, and the system includes:

[0110] GPS signal receiving module, used for receiving GPS signals;

[0111] The GPS digital signal acquisition module is used to perform low-noise amplification, filtering, down-conversion, re-filtering, re-amplification, sampling and quantization on the received GPS signal, and finally output the GPS digital signal;

[0112] The GPS M-code digital signal extraction module is used to extract the GPS M-code digital signal from the GPS digital signal by using a bandpass filtering method;

[0113] The low-orbit satellite platform data reading module is used to read the dynamic information data of the low-orbit satellite platform;

[0114] GPS satellite data reading module, used to read GPS satellite dynamic information data;

[0115] Delay and Doppler estimation module, used to estimate GPS M-code signal delay and Doppler;

[0116] The carrier phase estimation module is used to estimate the carrier phase of the GPS M code signal according to the estimated delay and Doppler of the GPS M code signal;

[0117] A local carrier generation module is used to generate a local carrier of the GPS M code signal based on the carrier phase of the GPS M code signal;

[0118] The carrier demodulation module is used to multiply the generated GPS M-code signal local carrier with the GPS M-code digital signal extracted by filtering to complete the GPS M-code signal carrier demodulation;

[0119] Pseudo-code elimination module, used to eliminate pseudo-code of GPS M-code signal;

[0120] A signal-to-noise ratio improvement module is used to improve the signal-to-noise ratio of the signal component obtained after the GPS M-code signal pseudo-code is eliminated through coherent integration;

[0121] The signal power estimation module is used to estimate the GPS M-code signal power.

[0122] The present application may also provide a computer device comprising: at least one processor, memory, at least one network interface, and a user interface. The various components in the device are coupled together via a bus system. It will be understood that the bus system is used to enable communication between these components. In addition to a data bus, the bus system also includes a power bus, a control bus, and a status signal bus.

[0123] The user interface may include a display, a keyboard, or a pointing device, such as a mouse, a trackball, a touchpad, or a touch screen.

[0124] It is understood that the memory in the embodiments disclosed in the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous DRAM (DDRSDRAM), enhanced synchronous DRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct RAM bus RAM (DRRAM). The memories described herein are intended to include, but are not limited to, these and any other suitable types of memory.

[0125] In some embodiments, the memory stores the following elements, executable modules or data structures, or a subset or an extension thereof: an operating system and applications.

[0126] The operating system includes various system programs, such as the framework layer, core library layer, and driver layer, which are used to implement various basic services and handle hardware-based tasks. Application programs include various application programs, such as media players and browsers, which are used to implement various application services. The program that implements the method of the embodiment of the present disclosure can be included in the application program.

[0127] In the above embodiment, the processor may also call a program or instruction stored in the memory, specifically, a program or instruction stored in the application program, to:

[0128] Perform the steps of the above method.

[0129] The above method can be applied to or implemented by a processor. The processor may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method can be completed by hardware integrated logic circuits in the processor or by software instructions. The above processor may be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. The above-disclosed methods, steps, and logic block diagrams can be implemented or executed. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the above-disclosed method can be directly implemented and executed by a hardware decoding processor, or by a combination of hardware and software modules in the decoding processor. The software module can be located in a storage medium well-known in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, etc. The storage medium is located in the memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the above method.

[0130] It is understood that the embodiments described herein may be implemented using hardware, software, firmware, middleware, microcode, or a combination thereof. For hardware implementation, the processing unit may be implemented in one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), general-purpose processors, controllers, microcontrollers, microprocessors, or other electronic units or combinations thereof for performing the functions described herein.

[0131] For software implementation, the technology of the present application can be implemented by executing the functional modules (e.g., procedures, functions, etc.) of the present application. The software code can be stored in a memory and executed by a processor. The memory can be implemented in the processor or external to the processor.

[0132] The present application may also provide a non-volatile storage medium for storing a computer program. When the computer program is executed by a processor, each step in the above method embodiment can be implemented.

[0133] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of this application and are not intended to limit the scope of the present invention. Although this application has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions to the technical solutions of this application do not depart from the spirit and scope of the technical solutions of this application and should be encompassed by the claims of this application.

Claims

1. A method for space-based monitoring of GPS M-code signal power, comprising: Step S101: receiving GPS signals; Step S102: The received GPS signal is sequentially subjected to low-noise amplification, filtering, down-conversion, re-filtering, re-amplification, sampling and quantization, and finally output as a GPS digital signal; Step S103: extracting the GPS M-code digital signal from the GPS digital signal using a bandpass filter; Step S104: Reading low-orbit satellite platform dynamic information data; Step S105: Read GPS satellite dynamic information data; Step S106: Estimate GPS M-code signal delay and Doppler; Step S107: estimating the carrier phase of the GPS M-code signal based on the estimated delay and Doppler of the GPS M-code signal; Step S108: Generate a GPS M-code signal local carrier based on the carrier phase of the GPS M-code signal; Step S109: multiplying the generated GPS M-code signal local carrier with the GPS M-code digital signal extracted by filtering to complete GPS M-code signal carrier demodulation; Step S110: performing pseudo code elimination on the GPS M code signal; Step S111: improving the signal-to-noise ratio of the signal component obtained after the GPS M-code signal pseudo-code is eliminated through coherent integration; Step S112: Estimate the GPS M-code signal power.

2. The method for monitoring GPS M-code signal power based on space according to claim 1, wherein: In step S104, the dynamic information data of the low-orbit satellite platform is read, including the real-time position and real-time speed of the low-orbit satellite platform.

3. The method for monitoring GPS M-code signal power based on space according to claim 1, wherein: In step S105 , GPS satellite dynamic information data is read, including the real-time position and real-time speed of the GPS satellite.

4. The method for space-based monitoring of GPS M-code signal power according to claim 1, wherein: The GPS M-code signal delay and Doppler in step S106 are expressed as: Among them, τ i (n) and d i (n) represents the delay and Doppler of the GPS M-code signal broadcast by the i-th GPS satellite reaching the low-orbit satellite platform; c represents the speed of light in vacuum; f L Indicates the carrier center frequency corresponding to the center frequency point of the current GPS M code signal; P L (n) represents the real-time position of the low-orbit satellite platform; P G,i (n) represents the real-time position of the i-th GPS satellite; V L (n) represents the real-time speed of the low-orbit satellite platform; V G,i (n) represents the real-time velocity of the i-th GPS satellite; ||·|| represents the modulus of the orientation quantity.

5. The method for monitoring GPS M-code signal power based on space according to claim 1, wherein: In step S107, the carrier phase of the GPS M-code signal broadcast by the i-th GPS satellite arriving at the low-orbit satellite platform is expressed as: in, represents the carrier phase of the GPS M-code signal broadcast by the i-th GPS satellite arriving at the low-orbit satellite platform; f L Indicates the carrier center frequency corresponding to the center frequency point of the current GPS M code signal; n represents the nth signal data obtained by sampling; T s represents the sampling interval; τ i (n) and d i (n) represents the delay and Doppler of the GPS M-code signal broadcast by the i-th GPS satellite reaching the low-orbit satellite platform.

6. The method for space-based monitoring of GPS M-code signal power according to claim 1, wherein: In step S108, the generated GPS M-code signal local carrier is represented as: Among them, Car i (n) represents the local carrier of the GPS M-code signal generated by the i-th GPS satellite; j represents the imaginary unit; It represents the carrier phase of the GPS M-code signal broadcast by the i-th GPS satellite arriving at the low-orbit satellite platform.

7. The method for space-based monitoring of GPS M-code signal power according to claim 1, wherein: In step S110, the GPS M-code signal pseudo code is eliminated using the square method, which is expressed as: C M,i (n)=[D M,i (n)] 2 Among them, C M,i (n) represents the result after the pseudo code of the GPS M code signal broadcast by the i-th GPS satellite is eliminated; D M,i (n) represents the result of carrier demodulation of the GPS M-code signal broadcast by the i-th GPS satellite.

8. The method for space-based monitoring of GPS M-code signal power according to claim 1, wherein: The coherent integration in step S111 is expressed as: Where N represents the number of data accumulated in the coherent integration operation; k represents the kth coherent integration operation; R M,i (k) represents the kth coherent integration result; C M,i (n) represents the result after the pseudo code of the GPS M-code signal broadcast by the i-th GPS satellite is eliminated.

9. The method for space-based monitoring of GPS M-code signal power according to claim 1, wherein: In step S112, the GPS M-code signal power estimation method is: P M,i (k)=G M (Tp(k))·R M,i (k) Among them, G M (Tp(k)) represents the total gain of the space-based monitoring GPS M-code signal power system; Tp(k) represents the temperature of the RF front end of the space-based monitoring GPS M-code signal power system measured in real time; P M,i (k) represents the estimated GPS M-code signal power broadcast by the i-th GPS satellite; R M,i (k) represents the k-th coherent integration result.

10. A system for space-based monitoring of GPS M-code signal power, implemented based on the method according to any one of claims 1 to 9, characterized in that: The system comprises: GPS signal receiving module, used for receiving GPS signals; The GPS digital signal acquisition module is used to perform low-noise amplification, filtering, down-conversion, re-filtering, re-amplification, sampling and quantization on the received GPS signal, and finally output the GPS digital signal; The GPS M-code digital signal extraction module is used to extract the GPS M-code digital signal from the GPS digital signal by using a bandpass filtering method; The low-orbit satellite platform data reading module is used to read the dynamic information data of the low-orbit satellite platform; GPS satellite data reading module, used to read GPS satellite dynamic information data; Delay and Doppler estimation module, used to estimate GPS M-code signal delay and Doppler; The carrier phase estimation module is used to estimate the carrier phase of the GPS M-code signal based on the estimated delay and Doppler of the GPS M-code signal; A local carrier generation module is used to generate a local carrier of the GPS M code signal based on the carrier phase of the GPS M code signal; The carrier demodulation module is used to multiply the generated GPS M-code signal local carrier with the GPS M-code digital signal extracted by filtering to complete the GPS M-code signal carrier demodulation; Pseudo-code elimination module, used to eliminate pseudo-code of GPS M-code signal; A signal-to-noise ratio improving module, configured to improve the signal-to-noise ratio of a signal component obtained after the GPS M-code signal pseudocode is eliminated through coherent integration; and The signal power estimation module is used to estimate the GPS M-code signal power.

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