Master-slave distributed synchronous satellite navigation decoy system and control method

Abstract

The invention provides a master-slave distributed synchronous satellite navigation decoy system and a control method, and belongs to the field of satellite navigation. The system is composed of a master control station and a plurality of synchronous deception signal generators arranged in different directions. And the master control station plans a deception trajectory by using a closed-loop control principle according to modes and parameters set by a user, satellite signal parameters output by the common-view GNSS receiver and target position and speed information transmitted by the detection system, generates a satellite number distribution and power control strategy, and generates a control instruction. And the master control station controls the deception signal generator to generate and emit a navigation deception signal causing false GNSS positioning according to the flow of the GNSS navigation signal simulator. When the signal reaches a target GNSS receiver antenna, the signal is synchronized with a GNSS satellite signal received by a target so as to control and decoy an integrated navigation system carried on the target, so that the target deviates from a preset course and track, and the purpose of hiding and efficiently preventing the target from invading a no-fly zone is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of satellite navigation, and in particular relates to a master-slave distributed synchronous satellite navigation deception system and a control method. Background Art

[0002] GNSS (Global Navigation Satellite System) deception and jamming technology plays an important role in defending and controlling drones from invading no-fly zones.

[0003] The civilian signal system of GNSS is public and the power of satellite signals reaching the ground is weak, which makes it easy to be interfered by artificially generated spoofing signals that are similar to real GNSS satellite signals but lead to false navigation and positioning results. With the development of GNSS navigation spoofing technology, the technology to combat GNSS spoofing has also developed rapidly, making the deception interference method using a single spoofing signal generation and transmission source gradually lose its advantages. For example, GNSS navigation receivers using multiple antennas or array antennas can suppress spoofing signals by detecting and identifying the direction of the arriving signal, causing the spoofing source to lose its concealment and effectiveness.

[0004] Therefore, the distributed GNSS spoofing method using multiple spoofing sources can simulate the GNSS space constellation to a certain extent, has stronger concealment, and can effectively deal with the detection and identification of the direction of the arriving signal.

[0005] In a distributed system, each spoofing source adopts a synchronous spoofing method, which will be beneficial to concealment. Asynchronous spoofing methods usually rely on the power of the spoofing signal to be significantly higher than the power of the real GNSS signal to implement repressive spoofing. The method is simple but has a high risk of being identified by spoofing detection methods. Synchronous spoofing estimates the power, code phase, carrier Doppler and other parameters of the real GNSS signal, simulates the generation of spoofing signals including code phase alignment, power gradual enhancement and code phase traction change process, and implements navigation spoofing without being easily detected by GNSS navigation receivers.

[0006] The current GNSS spoofing signal sources are mainly single-machine, which makes it difficult to build a multi-satellite multi-signal deception interference scenario, and difficult to deal with GNSS navigation spoofing detection based on multiple antennas or array antennas. Summary of the invention

[0007] The present invention provides a master-slave distributed synchronous satellite navigation deception system and control method, which can realistically simulate multiple GNSS satellite signals within the field of view of a GNSS receiver during the actual GNSS satellite signal reception process, generate highly similar and highly concealed GNSS navigation deception signals, thereby constructing a deception interference environment for the GNSS receiver; it can form various deception interference scenarios, and provide effective tools for modeling and simulating various deception effects and testing and evaluating the anti-deception performance of the receiver, and can be applied to the fields of drone control and electronic countermeasures.

[0008] The master-slave distributed synchronous satellite navigation deception system includes: a master control station and multiple synchronous deception signal generators deployed in different positions.

[0009] The master control station consists of a master control software module, a common view GNSS receiver and a wireless communication module, and is connected to the deceiving target's detection system through a wired or wireless link.

[0010] Each deception signal generator consists of a navigation deception signal generation module, a GNSS timing receiver and a wireless communication module. The navigation deception signal generation module includes: an ARM processor, an FPGA circuit and a radio frequency transceiver.

[0011] In the master control station, the user sets the working mode, desired spoofing trajectory and speed parameters through the interface of the master control software module; the master control station also receives the spoofed target position and speed sent back by the target detection system, and observes the real GNSS satellite signal parameters and satellite number through the common view GNSS receiver.

[0012] The main control software module assigns a satellite number to each spoofing signal generator and calculates the corresponding spoofing signal power based on the real GNSS signal parameters. The spoofing signal power is close to the signal power of the real satellite.

[0013] Furthermore, based on the real-time position of the deception target and the deception trajectory expected by the user, the main control software module plans the deception trajectory in real time based on the PID closed-loop control, calculates the control parameters and instruction parameters used to generate the deception signal in real time, and packages them and sends them to each deception signal generator through the wireless communication module.

[0014] The navigation decoy signal generation module of each deception signal generator modulates and generates deception signals. The GNSS timing receiver receives and processes the GNSS satellite signals and telegram information corresponding to the satellite number assigned by the master control station to initialize the ephemeris parameters. The high-precision clock signal output by the GNSS timing receiver is used to synchronize the local clock of the deception signal generator with the GNSS system time. At the same time, the pseudo code and intermediate frequency carrier corresponding to the assigned satellite number are generated by direct digital frequency synthesis, and the digital intermediate frequency signal is obtained by multiplying it with the telegram. The digital intermediate frequency signal is sent to the RF transceiver for digital-to-analog conversion, filtering, up-conversion and amplification to obtain a RF-level deception signal.

[0015] The generated deception signal can be expressed as:

[0016]

[0017] Among them, P i The deception signal power allocated to the master station; C i is a pseudo (random) code; D i It is the message data corresponding to the ephemeris parameters output by the GNSS timing receiver; cos(2πf i t+θ i ) is the carrier signal.

[0018] The spoofing signal generator will report the status and validity of the spoofing signal generation to the master control station. The master control station will display the validity report of each spoofing signal generator to the user. The user can modify and reset the desired spoofing trajectory, further generate control parameters and command parameters, and then send them to each spoofing signal generator. The spoofing signal generator receives the parameters and instructions from the master control station, estimates the parameters of the real GNSS satellite signal at the spoofing target position, and then generates and transmits the navigation spoofing signal according to the workflow of the GNSS signal simulator.

[0019] The specific functions are divided into:

[0020] Each spoofing signal generator receives the control parameters and command parameters from the master control station through the wireless communication module and transmits them to the ARM processor. The ARM processor is connected to the GNSS timing receiver to obtain the GNSS system time and ephemeris parameter information. According to the synchronous spoofing generation method, the real GNSS signal parameters at the spoofing target position are estimated, and then the spoofing signal parameters are generated according to the workflow of the GNSS simulator and sent to the FPGA circuit.

[0021] The FPGA circuit contains parallel signal processing and generation channels. Each channel has a code NCO, a message buffer, and a carrier DDS, which generate pseudo code, message bits, and a carrier signal containing Doppler. The three-layer signal of the message, pseudo code, and carrier is equivalently multiplied through a combinational logic circuit, and finally multiplied by the power control word to obtain the signal S i (t) in digital intermediate frequency form, and then sent to the RF transceiver via the LVDS bus;

[0022] The RF transceiver integrates modules such as digital-to-analog converters, filters, local crystal oscillators, PLLs, mixers and amplifiers, and has a complete RF front end and antenna.

[0023] The master-slave distributed synchronous satellite navigation deception system and control method comprises the following specific steps:

[0024] Step 1: After the spoof signal generator is powered on, the ARM processor is initialized and the FPGA circuit is configured.

[0025] Step 2: The ARM processor waits to receive the message information output by the GNSS timing receiver through the serial port to initialize the ephemeris parameters.

[0026] The GNSS timing receiver continuously outputs the ephemeris parameters of each visible star. The ARM processor collects a main frame message from all visible stars; when the message information is loaded and the validity is judged, the valid signal channel is enabled, the message is parsed and the ephemeris is extrapolated, the ephemeris parameter structure is constructed, and the ephemeris and message parameters are initialized.

[0027] Step 3: The spoofing signal generator calibrates the local crystal oscillator frequency of the spoofing signal generator according to the GNSS system time information provided by the GNSS timing receiver, thereby achieving synchronization between the local clock and the GNSS time.

[0028] Step 4: The master control station sends the start command and the location coordinates of the deceptive target through the wireless communication module. After receiving the command, the ARM processor sends the signal channel control word to the FPGA circuit to enable the channel. The deceptive signal generator starts to modulate and generate and transmit the deceptive signal into the air.

[0029] Step 5: After the master station is started, it enters the waiting state to check the validity of the deception target position information returned from the target detection system and the user input settings. When the user settings are confirmed to be valid, the master station sends instructions to the deception signal generator.

[0030] Step 6. After receiving the command from the master control station, the spoofing signal generator performs synchronous spoofing signal generation, controls the spoofing signal generated by its signal channel to align the code phase with the real satellite signal at the spoofing target receiving antenna, and then gradually enhances the spoofing signal power to affect the tracking loop of the spoofing target GNSS receiver, and gradually pulls the code phase to capture and control the tracking loop of the target receiver, and finally changes the GNSS navigation results of its positioning coordinates and time.

[0031] Step 7: The main control software module will use the PID control algorithm to plan the deception trajectory in real time according to the real-time position of the deception target provided by the target detection system and the deception trajectory expected by the user.

[0032] In summary, the beneficial effects of the present invention are as follows:

[0033] 1. Multiple spoofing signal generators can be used to generate spoofing signals with different arrival directions, more realistically simulating the actual GNSS space constellation, concealing the spatial characteristics of the spoofing signals, and thus improving the success rate of spoofing.

[0034] 2. It can invade the target navigation receiver and control its tracking loop with low-power deceptive signals. The deceptive process is covert and not easily detected by the deceptive target.

[0035] 3. Based on the output of the target detection device, the real-time position and speed of the deceptive target can be obtained, and the deceptive trajectory can be closed-loop controlled so that the motion trajectory of the deceptive target gradually approaches the deceptive trajectory preset by the user.

[0036] 4. The user inputs and configures the system and target deception through the interface of the main control software module. The main control station controls the topological structure of each deception signal generator, which can effectively simplify user operations. At the same time, multiple deception signal generators can work together through the deception signal generation task allocation.

[0037] 5. The deception signal generator is based on a new architecture platform of ARM+FPGA+AD9361, which improves the system integration and stability and reduces the system cost and volume. The navigation deception signal is generated in a fully digital way, which improves the accuracy and stability of the deception signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of the structure of a master-slave distributed synchronous satellite navigation deception system of the present invention;

[0039] Figure 2 It is a schematic diagram of the composition of a master-slave distributed synchronous satellite navigation deception system in an embodiment of the present invention;

[0040] Figure 3 is a schematic diagram of a navigation deception signal generator in an embodiment of the present invention;

[0041] Figure 4 Schematic diagram of the implementation and interface mode of the spoofing signal generator in the embodiment of the present invention;

[0042] Figure 5 A schematic diagram of a navigation deception signal generation process in an embodiment of the present invention;

[0043] Figure 6 It is a schematic diagram of the deception signal capture and control target receiver signal tracking in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to facilitate the system construction and method implementation, the present invention is further described below in conjunction with the accompanying drawings and embodiments. The described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, other forms of embodiments derived should belong to the scope of protection of the present invention.

[0045] The present invention provides a master-slave distributed synchronous satellite navigation deception system and control method, which can generate GNSS navigation deception signals with multiple signal arrival directions, concealed deception process and leading to false positioning results.

[0046] like Figure 1 and Figure 2 As shown, the master-slave distributed synchronous satellite navigation deception system consists of a master control station and multiple synchronous navigation deception signal generators. Among them, the master control station consists of a master control software module, a common view GNSS receiver and a wireless communication module, and is connected to the target detection system through a wired or wireless link. The synchronous satellite navigation deception signal generator can be flexibly deployed on a ground-based, air-based or satellite-based platform, and is mainly composed of a navigation deception signal generation module, a GNSS timing receiver and a wireless communication module.

[0047] The master-slave distributed synchronous satellite navigation deception system and control method include:

[0048] The master control station plans the deception trajectory in real time using the closed-loop control principle according to the working mode and parameters set by the user through the master control software interface, the real satellite signal parameters calculated and output by the common view GNSS receiver, and the real-time position and speed of the deception target transmitted by the target detection system. It allocates the satellite number and the power of the deception signal according to the number of synchronous navigation deception signal generators greater than or equal to 2, generates control parameters and instructions, and sends them to each deception signal generator to control the deception signal generator to generate and transmit GNSS navigation deception signals according to the workflow of the GNSS satellite navigation signal simulator. The navigation deception signal generated in this way is synchronized with the real satellite signal received by the target when it reaches the target GNSS receiver antenna, thereby manipulating and deceiving the GNSS and its combined navigation system carried by the target at a low power cost, causing its movement to deviate from the course and track, and achieving the purpose of countering its intrusion in a covert, flexible and efficient manner. The following two points need to be explained:

[0049] (1) The target receiver refers to the GNSS receiver carried by the intrusion target (such as a drone), which is the object deceived by the system and method of the present invention and does not fall within the scope of the present invention.

[0050] (2) The target detection system can directly use existing products or modules, such as radar and visual detection equipment, which does not fall within the scope of the present invention.

[0051] The master control station packages the aforementioned command parameters and data parameters and sends them to each spoof signal generator through the wireless communication module (Lora). Each spoof signal generator uses the same communication module to receive the commands and parameters from the master control station, and after receiving and parsing them in the ARM processor, they are used to modulate and generate navigation spoof signals. At the same time, the spoof signal generator sends its own status and other information to the master control station. The content definition of the Lora wireless communication protocol is shown in Table 1 below.

[0052] Table 1

[0053]

[0054] In the master control station, users can set the working mode, desired deception trajectory and speed parameters through the interface of the master control software module.

[0055] The master control station simultaneously receives the deceptive target position and speed sent back by the target detection system, and the real GNSS satellite signal parameters and satellite number observed by the common view GNSS receiver.

[0056] The main control software module assigns satellite numbers to each spoofing signal generator and calculates the spoofing signal power based on the GNSS satellite signals and information that are in the same field of view as the spoofing target. The spoofing signal power is close to that of the real satellite.

[0057] Furthermore, based on the real-time feedback of the position of the deception target and the user's expected deception trajectory, the main control software module plans the deception trajectory in real time based on PID closed-loop control, calculates the control parameters and instruction parameters used to generate the deception signal in real time, and packages them and sends them to each deception signal generator through the wireless communication module.

[0058] The synchronous satellite navigation deception signal generator of the present invention comprises: an ARM processor, an FPGA circuit and a radio frequency transceiver.

[0059] Principle Figure 3 , Figure 4 and Figure 5 As shown in the figure, each spoofing signal generator also receives the control parameters and instruction parameters of the master control station through the wireless communication module and transmits them to the ARM processor. The ARM processor receives the spoofing signal parameters corresponding to the spoofing trajectory from the master control station. At the same time, the ARM processor is connected to the GNSS timing receiver to obtain the GNSS system time and satellite ephemeris parameters. The real GNSS signal parameters at the spoofing target position are estimated according to the synchronous spoofing method, and then the spoofing signal parameters are generated according to the workflow of the GNSS simulator, including the satellite number, power, telegram, code frequency control word and Doppler frequency control word of each parallel signal channel. The modulation parameters are packaged and sent to the FPGA circuit through the AXI bus for signal modulation and generation.

[0060] The FPGA circuit contains parallel signal processing and generation channels. Each channel has a code NCO, a message buffer, and a carrier DDS, which generate pseudo code, message bits, and a carrier signal containing Doppler. The three-layer signal of the message, pseudo code, and carrier is equivalently multiplied through a combinational logic circuit, and finally multiplied by the power control word to obtain the spoofing signal S. i The digital intermediate frequency form of (t) is then sent to the RF transceiver (AD9361) through the LVDS bus for digital-to-analog conversion and up-conversion.

[0061] The RF transceiver integrates modules such as digital-to-analog converters, filters, local crystal oscillators, PLLs, mixers and amplifiers, and has a complete RF front end and antenna.

[0062] The navigation spoofing signal generation module modulates and generates spoofing signals, and initializes the ephemeris parameters by converting the GNSS satellite signals and telegram information corresponding to the satellite numbers output by the GNSS timing receiver. The high-precision 10MHz clock signal output by the GNSS timing receiver synchronizes the local clock with the GNSS system time. At the same time, the pseudo code and intermediate frequency carrier corresponding to the satellite number are generated by direct digital frequency synthesis, and the digital intermediate frequency signal is obtained by multiplying the telegram. The digital intermediate frequency signal is sent to the RF transceiver for digital-to-analog conversion, filtering, up-conversion and amplification to obtain a synchronous spoofing signal.

[0063] The generated deception signal can be expressed as:

[0064]

[0065] Among them, P i The deception signal power allocated to the master station; C i is a pseudo (random) code; D i It is the message data corresponding to the ephemeris parameters received by the GNSS timing receiver; cos(2πf i t+θ i ) is the carrier signal.

[0066] The spoofing signal generator reports the status and validity of the spoofing signal generation to the master control station. The master control station displays the validity report of each spoofing signal generator to the user. The user can re-enter the working mode and reset the desired spoofing trajectory and speed to the master control station through the host computer interface. The spoofing signal generator receives the parameters and instructions of the master control station, estimates the parameters of the real GNSS satellite signal at the spoofing target position, and then generates and transmits the navigation spoofing signal according to the workflow of the GNSS signal simulator.

[0067] The master-slave distributed synchronous satellite navigation deception system and control method comprises the following specific steps:

[0068] Step 1: After the spoof signal generator is powered on, the ARM processor is initialized and the FPGA circuit is configured.

[0069] Step 2: The ARM processor waits to receive the message information output by the GNSS timing receiver through the serial port to initialize the ephemeris parameters.

[0070] The GNSS timing receiver continuously outputs a main frame message for each visible star, and the ARM processor collects the main frame messages of all visible stars. When the message information is loaded and the validity is judged, the valid signal channel is enabled, the message is parsed and the ephemeris is extrapolated, the ephemeris parameter structure is constructed, and the ephemeris and message parameters are initialized.

[0071] Step 3: The spoofing signal generator calibrates the local crystal oscillator frequency of the spoofing signal generator according to the GNSS time information provided by the GNSS timing receiver, thereby achieving synchronization between the local clock and the GNSS time.

[0072] After receiving the positioning and time information output by the GNSS timing receiver, the ARM processor receives the count value of the local crystal oscillator between the 1PPS pulse signals and recalibrates the crystal oscillator frequency to achieve time synchronization with the GNSS system.

[0073] Step 4: The master control station sends the start command and the location coordinates of the deceptive target through the wireless communication module. After receiving the command, the ARM processor enables the channel by sending a signal channel control word to the FPGA circuit and lights up the operation indicator light, indicating that the deceptive signal generator starts to modulate, generate and transmit the signal.

[0074] Step 5: After the master station is started, it enters the waiting state to check the validity of the deception target position information returned from the target detection system and the user input settings. When the user settings are confirmed to be valid, the master station sends instructions to the deception signal generator.

[0075] Step 6. After receiving the command, the spoofing signal generator starts to execute synchronous spoofing signal generation, controls the spoofing signal generated by its signal channel to align the code phase with the real satellite signal at the spoofing target antenna, and then gradually enhances the spoofing signal power to affect the tracking loop of the spoofing target GNSS navigation receiver, and gradually pulls the code phase to capture and control the tracking loop of the target receiver, and finally changes the GNSS navigation results of its positioning coordinates and time.

[0076] Step 7: The main control software module will use the PID control algorithm to plan the deception trajectory in real time according to the actual position of the deception target provided by the detection system and the deception trajectory expected by the user.

[0077] Example:

[0078] like Figure 3 As shown, the navigation deception signal generation module includes: an ARM processor, an FPGA (Field Programmable Gate Array) circuit and a radio frequency transceiver module. Among them, the ARM processor and the FPGA circuit constitute the intermediate frequency digital signal generation part. The ARM processor is suitable for complex mathematical calculations and multi-task control, and is used to calculate signal modulation parameters; the FPGA is suitable for high-speed parallel computing, used to generate digital intermediate frequency signals, and is responsible for global clock control.

[0079] The ARM processor is used to control the task flow of the spoofing signal generator, communicate with the master control station to obtain control parameters and instructions, and connect to the GNSS timing receiver to obtain GNSS system time and ephemeris parameters. After the estimation of the real signal parameters at the spoofing target is completed according to the synchronous spoofing strategy, the debugging parameters are generated according to the workflow of the GNSS simulator and sent to the FPGA circuit.

[0080] The FPGA circuit generates a digital intermediate frequency signal according to the modulation parameters calculated by the ARM processor and driven by a sampling clock based on a local clock.

[0081] The RF transceiver is used to convert the digital intermediate frequency signal generated by the FPGA circuit into a RF signal.

[0082] like Figure 4 As shown, the ARM processor includes: a parameter initialization module, an instruction receiving module, an ephemeris extrapolation module, a signal transmission time calculation module and a parameter updating module.

[0083] The above parameter initialization module is implemented through the communication serial port and string processing program.

[0084] The FPGA circuit comprises: a code NCO, a Doppler carrier DDS, a message ping-pong buffer, an interrupt event generator and a LVDS transceiver.

[0085] Driven by the sampling clock, the Doppler carrier DDS and code NCO output the Doppler carrier signal and pseudo-random code by table lookup. DDS uses a dedicated DDS compiler IP to generate a sine wave. When the sampling rate is set to 40MHz, the frequency resolution is set to 0.1Hz, the dynamic range is 45dB, the phase and frequency control words are external inputs, and the sine-cosine mode is output. The DDS phase wheel bit width is set to 22 bits and the output is 12 bits. The DDS has a phase wheel lookup table structure inside. For the negative frequency, the periodic characteristics of the phase wheel can be used to superimpose a phase wheel module length on all frequency control words to achieve positive and negative frequency control of the IQ complex signal. The code NCO also uses a table lookup method to generate and store all the required pseudo codes in the ROM in advance. The pseudo code required for the current modulation can be output by taking the high 10 bits of the code phase wheel as the address. When the sampling frequency is fixed, the code frequency control value is determined by the code phase wheel bit width.

[0086] The message ping-pong controller controls the alternating reading and writing between the two segments of messages to ensure the continuous writing of messages by ARM and the continuous reading of messages by FPGA. The transmission and reception of messages are in units of words, which are combined in ARM and sent to FPGA through AXI bus for modulation.

[0087] The interrupt event generator is used to generate global update events. The system runs with interrupt events as the smallest unit, including ARM processor interrupt transactions and FPGA update transactions. It is essentially a counter that can generate two pulse signals, one is the ARM processor interrupt signal, which is used to trigger the ARM interrupt; the other is the FPGA interrupt signal, which uses the FPGA part to update the channel parameters. The period of the counter is the period of updating the parameters. It is limited by the computing speed of the ARM processor. This period is 0.001s, which can ensure that the calculation and writing of the new parameters are completed. The count value is 4×10 4. When the counter is reset, the ARM processor interrupt signal is pulled high, triggering the ARM interrupt, and the ARM side starts to calculate the parameters of the next parameter update cycle. After the calculation is completed, a valid signal is generated. At the end of the count, the FPGA interrupt generates a pulse with a width of 1. When the pulse and valid are both valid, each channel updates the parameters under the sampling clock. By designing the timing of the ARM processor interrupt and the FPGA interrupt, the task process of the ARM side and the FPGA side is coordinated to avoid the problem of cross-clock communication, so that the initiative of the timing is on the FPGA side, and the ARM side only needs to perform operations without precise requirements for the clock frequency.

[0088] The LVDS transceiver is implemented through Xilinx's ODDR and ODRV primitives, using the hardware circuit inside the chip. ODRV converts single-ended signals into differential signals; ODDR converts single-edge signals into double-edge signals. The signal of a sampling point is divided into four groups for transmission: I, Q, high and low. After the data is converted into double-edge, the data rate is doubled. For this purpose, the FPGA IP core is used to double the communication clock.

[0089] Preferably, the ARM processor and FPGA use the ZYNQ XC7Z020 SOC chip. ZYNQ is a heterogeneous programmable SOC that integrates CPU and FPGA of Xilinx, namely, the programmable logic part (Programmable Logic, FPGA) and the processing system (Processing System, ARM processor) part. ZYNQ combines the software programmability and hardware programmability of the processor, and provides a high-speed on-chip communication bus AXI between the two. AXI is far superior to traditional board-level communication in terms of throughput rate and stability. Generally speaking, FPGA has high-speed signal processing capabilities, while CPU is suitable for more complex task control. The two have complementary advantages and are suitable for occasions with large and complex computing tasks. Compared with traditional discrete heterogeneous platforms, ZYNQ simplifies the design complexity and difficulty of use, reduces the area, and improves system stability. The chip used in this embodiment is ZYNQ XC7Z020, in which the ARM processor part is a dual-core ARM Cortex A9 structure, and the FPGA part is Artix-7FPGA, which can support 8G DDR3 memory and integrate Gigabit Ethernet, 12-bit analog-to-digital converter (ADC), SD card controller, SPI interface, IIC interface, USB OTC interface and UART serial port.

[0090] Preferably, the RF transceiver adopts AD9361 transceiver. ADI's AD936x series chips fully integrate the RF link and directly provide a baseband data interface. The RF parameters are all digitally configured, which reduces the design difficulty of the RF part. The parameter configuration is completed by writing the register through the SPI interface.

[0091] AD9361 integrates complete transmission and reception functions, including dual-transmission and dual-reception four channels. The chip integrates digital control FPGAL, RF mixer, divider, digital filter, AD / DA converter and amplifier. The baseband data communication uses LVDS bus to improve the communication rate and anti-interference ability.

[0092] Preferably, the GNSS timing receiver uses the Ublox NEO-M8T receiver, which can not only output position and time positioning information, but also output original observation quantities such as telegrams and pseudoranges, as well as a high-precision 10MHz clock signal synchronized with the GNSS time. It is used as the preferred clock for keeping the local clock synchronized with the GNSS system.

[0093] Preferably, the wireless communication module uses a Lora wireless serial port module, which is essentially a converter between RS232 and Lora protocols, with a frequency of 433 MHz, a maximum transmission power of 0 dBm, and a maximum communication rate of 9600 bauds at a distance of 1 km in an open area.

[0094] The main processing flow of the above-mentioned navigation deception signal generator is as follows: Figure 5 shown.

[0095] After the navigation spoofing signal generator is powered on, the ARM processor first starts and configures the FPGA. Since the initial state of the channel is not enabled and the satellite time counter is not enabled, the channel will not have any output.

[0096] The ARM processor then starts to initialize the system and peripherals, and waits to receive the message output by the GNSS timing receiver through the serial port. The receiver will output a main frame message for each visible star until all the main frame messages of all visible stars are collected. When the message information is loaded and the validity is judged, only the channels that are verified to be valid are enabled. Next, the message will be extrapolated and parsed, the ephemeris parameter structure will be constructed, and the ephemeris and message parameters will be initialized.

[0097] After receiving the position coordinates and time output by the GNSS timing receiver, the preparations for implementing the deception strategy are also completed. The ARM processor also receives the 1PPS pulse signal count value output by the timing GNSS receiver to recalibrate the frequency of the local clock crystal, which is a key step in achieving time synchronization. At this point, the information initialization work is completed, and the system enters a state of waiting for instructions from the master control station, ready to modulate and generate deception signals. The master control station sends the start command and the signal parameters corresponding to the deception trajectory through the wireless communication serial port. After receiving the above information, the ARM processor sends a channel control word to the FPGA to enable the signal channel and lights up the operation indicator light, indicating that the device starts to modulate and transmit signals.

[0098] During the modulation process, the system runs with interrupt events as the basic unit. The FPGA is responsible for timing and generating interrupt signals, thereby triggering the ARM processor to calculate and update parameters, including signal channel status control words, transmission time, Doppler frequency, and telegram content. The interrupt frequency is the minimum task cycle unit. The system divides the work into multiple tasks according to different execution cycles. At the same time, UART1 is always ready to receive instructions and data. The interrupt priority of UART1 is lower than the interrupt priority of FPGA. When two interrupt events conflict, the FPGA interrupt is executed first. When the UART1 interrupt program is in execution, it can also be preempted by the FPGA interrupt. FPGA has the highest priority for the normal modulation, and no other program can affect the execution of FPGA interrupts. FPGA always runs the intermediate frequency digital signal modulation task, but the control parameters are constantly updated.

[0099] The master control station in the embodiment of the present invention is responsible for the top-level control of each synchronous satellite navigation spoofing signal generator, including a single-chip microcomputer, a GNSS receiver, a wireless communication module and a target detection device, etc. Preferably, the above-mentioned wireless communication module adopts the same configuration wireless communication module as that carried by the synchronous satellite navigation spoofing signal generator.

[0100] The operation and control process of the master control station is as follows: after startup, the master control station first enters a waiting state to check the validity of the deceptive position information returned from the target detection system and the user input settings. Then, it is up to the user to decide whether to proceed to the next step. If the user confirms the information, the master control station begins to issue instructions for transmitting signals. After receiving the instructions, the synchronous satellite navigation deceptive signal generator performs synchronous deception. The deceptive signals of each channel are controlled to be aligned with the code phase of the real satellite signal at the target antenna, and then the deceptive signal power is gradually enhanced to affect the tracking loop of the target receiver, and then the code phase is gradually pulled to complete the capture and control of the tracking loop of the target receiver, thereby changing the positioning results of its position and time. The schematic diagram of the deceptive signal capture and control of the target receiver signal tracking in this embodiment is shown in the figure. Figure 6As shown. Considering the instability of wireless communication, a state monitoring strategy is introduced in the processing flow. Communication is not performed only when sending and receiving instructions, but periodically. The master station performs interrupt processing at a frequency of 5Hz, executes all tasks, and ensures the effective execution of each task through conditional judgment.

[0101] The master station uses the serial port to communicate with all devices, with the baud rate of the wired serial port being 38400 and the baud rate of the wireless serial port being 9600. The single-chip microcomputer STM32G0B0 integrates 6 independent serial ports. All serial ports are controlled by interrupts. Since the delay caused by interrupt conflicts is in the order of microseconds, and there is no strict time limit in all communication tasks of the master station, there is no need to strictly configure the priority of the serial port interrupts. When wirelessly communicating with the spoofing signal generator, since the wireless serial port module model and frequency are the same, direct sharing will cause cross-station phenomenon. For this reason, the device number of the spoofing signal generator is added to the communication protocol frame of the master station, and the group call address is used. When a group call message is received, all spoofing signal generators can receive it, but only the spoofing signal generator corresponding to the address will respond.

[0102] The innovative features of the system and method of the present invention include:

[0103] (1) The designed hardware platform is more integrated than the traditional software radio platform, with lower volume, cost and power consumption. The baseband chip ZYNQ includes an ARM processor and FPGA; the RF transceiver chip AD9361 includes a complete RF link, thus realizing the functions of a complete software radio platform.

[0104] (2) In response to the needs of time synchronization and code phase estimation, a high-precision and robust timing method is designed to achieve synchronization between the local clock and the GNSS system time.

[0105] (3) In terms of navigation deception strategy, compared with asynchronous deception with larger signal power, the synchronous mode deception intrusion process adopted by the deception signal generator is more concealed.

[0106] The system and method of the present invention have the following design innovations:

[0107] (1) In order to achieve multiple arrival signal directions, multiple spoofing signal generators need to work together. For this purpose, a master control station is designed to coordinate the control of multiple spoofing signal generators. In addition, the master control station is also connected to the target detection device to obtain information such as the real-time location of the spoofed target, and provides a user-friendly master control software module.

[0108] (2) For spoofed targets such as drones, since their navigation systems do not rely solely on the GNSS system, but involve a combined navigation mode of the GNSS and inertial systems, there will be a significant deviation between the actual spoofed trajectory and the expected spoofed trajectory. A closed-loop control strategy is adopted to adjust the spoofed trajectory in real time, and then the control feedback is obtained based on the real-time position of the spoofed target transmitted back by the target detection device, and the spoofed trajectory is planned in real time to approach the spoofed trajectory expected by the user.

Claims

1. A master-slave distributed synchronous satellite navigation deception system, characterized in that: include: The master control station module plans the target's deception trajectory based on the working mode and expected target deception trajectory set by the user in the software interface, the real satellite signal parameters output by the common-view GNSS receiver and the target's real-time position and speed information transmitted by the target detection system, and uses the closed-loop control principle to generate satellite number allocation and power control strategies, and generates control parameters and instructions, which are sent to multiple synchronous satellite navigation deception signal generators through the wireless communication module; The synchronous satellite navigation spoofing signal generator generates parameters based on the spoofing signal sent by the master control station. It first generates a baseband-level spoofing signal through digital synthesis, and then obtains a digital intermediate frequency signal through digital orthogonal up-conversion. After digital-to-analog conversion, filtering, up-conversion and amplification, the digital intermediate frequency signal is converted into a RF-level spoofing signal and transmitted through the antenna.

2. The master-slave distributed synchronous satellite navigation deception system according to claim 1 is characterized in that: The number of the synchronous satellite navigation deception signal generators is greater than or equal to 2, and they are distributed in different directions of the deception target, and can form different signal arrival directions relative to the deception target.

3. The master-slave distributed synchronous satellite navigation deception system according to claim 1, characterized in that: The local clock of the synchronous satellite navigation spoofing signal generator is synchronized with the GNSS system time through training, and when the spoofing signal reaches the target GNSS receiver antenna, it is synchronized with the real GNSS satellite signal received by the target.

4. The master-slave distributed synchronous satellite navigation deception system according to claim 1, characterized in that: The synchronous satellite navigation deception signal generator comprises: The navigation decoy signal generation module generates parameters according to the deception signal sent by the master control station module, generates a digital intermediate frequency signal by direct digital frequency synthesis, and then obtains a radio frequency level deception signal after digital-to-analog conversion, filtering, up-conversion and amplification through an integrated radio frequency transceiver; GNSS timing receiver, which receives real GNSS satellite signals and estimates the signal state parameters required to generate spoofing signals. It also outputs high-precision clock synchronization signals to synchronize the local clock used to generate spoofing signals with the GNSS system time. The wireless communication module is used for communication and transmission of instructions, parameters and status information with the master control station.

5. The master-slave distributed synchronous satellite navigation deception system according to claim 1, characterized in that: The master control station comprises: The main control software module is used to interact with the user, display the target position and speed information sent back by the target detection system, plan the deception trajectory in real time, and generate satellite number allocation and power control strategies for each synchronous satellite navigation deception signal generator; A common view GNSS receiver module is used to obtain the GNSS satellite constellation distribution, satellite number information and satellite signal power estimation within the same field of view as the spoofing target; The wireless communication module is used for communicating and transmitting instructions, parameters and status information between each synchronous satellite navigation deception signal generator.

6. The master-slave distributed synchronous satellite navigation deception system according to claim 1, characterized in that: Multiple synchronous satellite navigation spoofing signal generators work together under the control of a master control station. Based on the real satellite signal parameters obtained by the common-view GNSS receiver and the distribution of the GNSS satellite constellation, the master control station assigns the satellite number corresponding to the spoofing signal generation channel, the power control word of the spoofing signal, and the spoofing signal parameters corresponding to the spoofing trajectory to each synchronous satellite navigation spoofing signal generator.

7. The master-slave distributed synchronous satellite navigation spoofing system according to claim 1 is characterized in that: in the communication uplink from the master control station to the synchronous satellite navigation spoofing signal generator, the communication content includes the satellite number assigned to the corresponding spoofing signal generation channel, the power control word of the spoofing signal, the spoofing signal parameters and working status corresponding to the spoofing trajectory; in the communication downlink from the synchronous satellite navigation spoofing signal generator to the master control station, the communication content includes the parameters of the spoofing signal generation channel and the status of the spoofing signal generator.

8. A synchronous satellite navigation spoofing signal control method based on a master-slave distributed synchronous satellite navigation spoofing system according to claim 1, characterized in that: include: First, the modulation parameters of the spoofing signal are calculated based on the real GNSS satellite signal parameters output by the GNSS timing receiver and the control parameters transmitted by the master control station; At the same time, the local clock is tamed based on the clock synchronization signal of the GNSS timing receiver; Then, a digital intermediate frequency level spoofing signal is generated through direct digital frequency synthesis and orthogonal up-conversion, and then a digital-to-analog conversion, filtering, up-conversion and amplification are performed through an integrated RF transceiver to obtain a RF level spoofing signal.

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