Low-orbit navigation simulator based on embedded data simulation software

Abstract

The invention discloses a low-orbit navigation simulator based on embedded data simulation software, which belongs to the technical field of low-orbit navigation system data simulation and consists of an embedded data simulation software module, a signal generation module, a time-frequency synchronization and shunt module and a power supply module. The embedded data simulation software module completes low-orbit navigation signal data simulation and sends simulated data to the signal processing module; the signal processing module interacts with embedded data simulation software, receives low-orbit navigation signal simulation data and completes generation of a baseband signal and a radio frequency signal; the time-frequency synchronization and shunt module is used for receiving a space real navigation signal, providing an ephemeris file and time, providing PPS and 10MHz time references for a hardware platform, and completing time synchronization of the low-orbit navigation simulator and the space navigation signal; and the power supply module supplies power to the low-orbit navigation simulator. According to the invention, various use requirements of vehicle-mounted, airborne, distributed unattended operation and the like can be met.

Description

Technical Field

[0001] The invention relates to the technical field of low-orbit navigation system data simulation, in particular to a low-orbit navigation simulator based on embedded data simulation software. Background Art

[0002] With the development of low-orbit navigation systems, low-orbit navigation simulators have emerged. As the core of low-orbit navigation simulators, low-orbit navigation simulator data simulation software needs to complete navigation system constellation simulation, error model simulation, pseudo-range observation simulation, message framing, channel control, etc. At present, low-orbit navigation simulator data simulation software mostly runs on external notebooks, industrial computers and other platforms. The interaction with the low-orbit navigation simulator is relatively complex, the number of devices is large, and the application scenarios are limited. Summary of the invention

[0003] In response to the low-cost and lightweight requirements of low-orbit navigation, the present invention proposes a low-orbit navigation simulator based on embedded data simulation software. The low-orbit navigation simulator data simulation software can be run on an embedded platform, supports independent operation, is not restricted by external simulation systems, does not rely on external devices, and can meet a variety of usage scenarios such as vehicle-mounted, airborne, and unmanned.

[0004] The object of the present invention is achieved in that:

[0005] A low-orbit navigation simulator based on embedded data simulation software, comprising an embedded data simulation software module, a signal generation module, and a time-frequency synchronization and branching module;

[0006] The embedded data simulation software module is used to complete the data simulation function of the low-orbit navigation simulator;

[0007] The signal generation module is used to complete the generation of baseband signals and radio frequency signals;

[0008] The time-frequency synchronization and branching module is used to receive real space navigation signals and provide ephemeris files and time for the data simulation module. It also provides PPS and 10MHz time reference to complete the time synchronization between the low-orbit navigation simulator and the space navigation signal.

[0009] The embedded data simulation software module receives the time and position information from the signal generation module as the simulation time and position reference, and simulates the low-orbit navigation signal that is synchronized with the real navigation signal in space based on the received real-time ephemeris data. The signal processing module generates baseband signals and radio frequency signals through the simulated navigation signals.

[0010] Furthermore, the embedded data simulation software module completes the low-orbit navigation system constellation simulation and error model simulation at the current moment, and completes the user trajectory simulation according to the simulation position and speed set by the low-orbit navigation simulator; based on the current user trajectory, the navigation system's space constellation simulation data and the space error model simulation data, completes the pseudo-range observation simulation calculation and message framing, and sends the pseudo-range observation and the framed message to the signal processing module.

[0011] Furthermore, the baseband signal generation process of the signal generation module is specifically as follows:

[0012] After receiving the pseudo-range observations and message frames from the data simulation module; the pseudo-range observations drive the code NCO and carrier NCO to generate pseudo-codes and carriers; the message frames are transmitted to the message parsing unit, and the message detection at the current moment is extracted according to the current simulation time; the pseudo-codes, carriers and message frames are digitally modulated to generate baseband digital simulation signals.

[0013] Furthermore, the radio frequency signal generation process of the signal generation module is specifically as follows:

[0014] After the signal generation module generates a digital baseband signal from FPGA, it sends the digital baseband signal to DA, completes the local oscillator configuration of DA according to the simulated frequency point, and generates a spread spectrum analog navigation signal of the corresponding frequency point.

[0015] Furthermore, the time-frequency synchronization and branching module is configured with a timing receiver, which receives the navigation signal from the space after being connected to an external receiving antenna. Relying on the real navigation signal in the space, it outputs synchronized PSS and 10MHz signals, and performs timing on the high-precision clock crystal oscillator of the time-frequency synchronization and branching module, so that the PSS and 10MHz output by the crystal oscillator are synchronized with the real signal in the space.

[0016] Furthermore, the time-frequency synchronization and branching module is configured with a high-precision clock crystal oscillator. After the device is powered on and started, the clock crystal oscillator will maintain a local PPS and 10MHz clock for normal startup and initialization of the device; the time-frequency synchronization and branching module is configured with a clock processing board to complete the branching of the PPS and 10MHz clock, and output the branched clock to the signal generation module to ensure the synchronization of the simulated low-orbit navigation signal and the space navigation signal.

[0017] Furthermore, the signal processing module reports the simulation status to the software, monitors the current signal simulation frequency, signal power and number of visible satellites, and can control the signal simulation frequency, transmission power and number of channels according to usage requirements.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The low-orbit navigation simulator based on embedded data simulation software designed by the present invention relies on embedded data simulation software and runs on an embedded platform. It can independently complete navigation data simulation, navigation signal generation, and navigation signal broadcasting. It supports independent operation, is not limited by external simulation systems, does not rely on external equipment, and meets various usage scenarios such as vehicle-mounted, airborne, and unmanned.

[0020] 2. The low-orbit navigation simulator based on embedded data simulation software designed by the present invention is based on a domestic platform, adopts the architecture of FPGA+ARM+DA, and the chip model is JFM7VX690T80+FMQL45T900+CX6242Q. It has high integration and can realize full-process independent design.

[0021] 3. The low-orbit navigation simulator designed by the present invention based on embedded data simulation software is configured with a DA chip, which can configure different numbers of DAs according to the simulation frequency and has multi-frequency output capability. The simulation frequency design of the low-orbit navigation simulator is flexible and suitable for a variety of usage requirements.

[0022] 4. The low-orbit navigation simulator based on embedded data simulation software designed by the present invention is equipped with a timing receiver. After an external receiving antenna is connected, it can receive navigation signals from space and output synchronized PSS and 10MHz signals. The signal generation module relies on synchronized PSS and 10MHz signals to output simulated navigation signals synchronized with space signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 It is the overall structural framework diagram of the present invention.

[0025] Figure 2 It is a design diagram of the embedded data simulation software module of the present invention.

[0026] Figure 3 It is a design diagram of the signal generating module of the present invention. DETAILED DESCRIPTION

[0027] In order to implement the present invention, the following Figure 1 , 2 and 3 for further details.

[0028] In view of the shortcomings of existing data simulation software, such as running on external devices, complex operation and limited usage scenarios, a low-orbit navigation simulator based on embedded data simulation software is designed. The low-orbit navigation simulator can rely on the embedded platform to complete the data simulation function of the low-orbit navigation simulator, realize navigation system constellation simulation, error model simulation, pseudo-range observation simulation, message framing, user trajectory simulation, etc. It can run independently without relying on external devices and meet various usage requirements such as vehicle-mounted, airborne, and distributed unmanned.

[0029] The overall design of the low-orbit navigation simulator based on embedded data simulation software designed by the present invention is composed of an embedded data simulation software module, a signal generation module, a time-frequency synchronization and branching module, and a power supply module. It has the functions of independent operation of the embedded data simulation software, digital signal simulation, and analog signal generation, and relies on an embedded platform to complete the low-orbit navigation signal simulation generation function.

[0030] The low-orbit navigation simulator based on embedded data simulation software consists of an embedded data simulation software module, a signal generation module, a time-frequency synchronization and branching module, and a power module. The embedded data simulation software module completes the low-orbit navigation signal simulation and sends the simulated data to the signal processing module; the signal processing module interacts with the embedded data simulation software module, receives the low-orbit navigation signal simulation data, and completes the baseband signal and RF signal generation; the time-frequency synchronization and branching module receives the real navigation signal in space, provides the embedded data simulation software module with the ephemeris file and time, and provides the hardware platform with the PPS and 10MHz time base to complete the time synchronization of the low-orbit navigation simulator and the space navigation signal; the power module provides power for the low-orbit navigation simulator.

[0031] The embedded data simulation software module runs on the PS side of FMQL45T900, and includes GTX interface, LVTTL interface, serial port, etc. between FPGA chip JFM7VX690T80 and DA chip CX6242Q. It supports interface protocols such as RapidIO and JESD204B, and can meet the data interaction, signal generation and signal output functions of embedded digital simulation software and signal processing module. The software generates low-orbit navigation signal simulation data and interacts with the signal processing module. The software sends the navigation signal simulation data to the signal processing module for navigation signal generation; the signal processing module reports the simulation status to the software for status monitoring and signal control. Among them, the embedded data simulation software module needs to complete the low-orbit navigation simulator data simulation function, and realize the navigation system constellation simulation, error model simulation, pseudo-range observation simulation, message framing, user trajectory simulation, channel control and monitoring equipment operation status according to the current user trajectory, navigation system space constellation simulation data and space error model simulation data, and send the pseudo-range observation and framed message to the signal processing module.

[0032] The embedded data simulation software module receives the time and position information from the signal generation module as the simulation time and position reference; based on the real-time ephemeris data reported by the signal generation module, it can simulate the low-orbit navigation signal synchronized with the real navigation signal in space, and achieve time and space unification with the space navigation signal.

[0033] The embedded data simulation software module can control the system frequency, simulation time, simulation position, and signal channel of the simulation according to the use requirements. For different scenarios, the frequency selection can be completed in a targeted manner, and during the operation, the channel control of the signal can be completed, and the current simulation status can be monitored in real time.

[0034] The signal generation module adopts FPGA+DA architecture, which mainly completes the generation of low-orbit navigation signal baseband signal and RF signal. The baseband signal generation includes code NCO design, carrier NCO design, navigation message generation design, signal modulation design, and generates intermediate frequency baseband signal; RF signal generation includes DA digital-to-analog conversion design and signal frequency conversion design to complete the processing of digital baseband signal to analog RF signal. The signal processing module fully considers the characteristics of low-orbit multi-frequency points, adopts high-performance multi-channel DA, and has the ability to output low-orbit multi-frequency points simultaneously. The simulation frequency point design of the low-orbit navigation simulator is flexible and suitable for a variety of usage requirements.

[0035] The baseband signal generation of the signal generation module is based on JFM7VX690T80. The signal generation module receives the pseudo-range observations and telegram frames simulated by the embedded data simulation software module. The pseudo-range observations drive the code NCO and carrier NCO to generate pseudo-codes and carriers; the telegram frames are transmitted to the telegram analysis module, and the telegram bits at the current moment are extracted according to the current simulation time; the pseudo-code, carrier and telegram frames are passed through the modulation module to generate baseband digital simulation signals. Relying on the PPS and 10MHz provided by the time-frequency synchronization and branching module, the code NCO, carrier NCO and telegram analysis module can accurately realize the output of pseudo-codes, carriers and telegrams.

[0036] The signal generation module generates radio frequency signals based on CX6242Q. After the signal generation module generates digital baseband signals from FPGA, it sends the digital baseband signals to CX6242Q, completes the local oscillator configuration of CX6242Q according to the simulated frequency point, and generates a spread spectrum analog navigation signal of the corresponding frequency point.

[0037] The time-frequency synchronization and branching module relies on high-precision clock crystals, timing receivers and clock processing boards to complete the synchronization of local time references with space signal time references and provide clocks for low-orbit navigation simulators. The timing receiver can complete the reception and processing of space signals, report ephemeris and time to the signal generation module and forward them to the embedded data simulation software module for navigation data simulation; the clock processing board completes the synchronization with the PPS and 10MHz clocks provided by the receiver, and branches the synchronized clock to provide clocks for low-orbit navigation simulators; the high-precision clock crystal provides local PPS and 10MHz, and independently provides PPS and 10MHz clocks without external timing capabilities.

[0038] The time-frequency synchronization and branching module is equipped with a high-precision clock crystal oscillator. After the device is powered on, the clock crystal oscillator will maintain a local PPS and 10MHz clock for normal startup and initialization of the device.

[0039] The time-frequency synchronization and branching module is equipped with a timing receiver. After being connected to an external receiving antenna, it can receive navigation signals from space, output synchronized PPS and 10MHz signals based on the real navigation signals in space, and perform timing on the high-precision clock crystal oscillator of the time-frequency synchronization and branching module, so that the PPS and 10MHz output by the crystal oscillator are synchronized with the real signals in space.

[0040] The time-frequency synchronization and branching module is equipped with a clock processing board to complete the branching of the PPS and 10MHz clocks, and output the branched clocks to the signal generation module to ensure the synchronization of the analog navigation signal and the space navigation signal.

[0041] The power module includes a power filter module and a power conversion module. The power filter is used for power filtering to provide stable and reliable 220V AC power for the equipment. The power conversion module converts the external 220V AC power into 12V DC power for internal use, which is used to power the internal modules of the low-orbit navigation simulator.

[0042] Figure 1 It is an overall block diagram of a low-orbit navigation simulator based on embedded data simulation software designed by the present invention.

[0043] The low-orbit navigation simulator based on embedded data simulation software designed by the present invention consists of four parts, namely, an embedded data simulation software module, a signal generation module, a time-frequency synchronization and branching module, and a power supply module.

[0044] The embedded data simulation software module completes the low-orbit navigation signal simulation and sends the simulated data to the signal processing module; the signal processing module interacts with the embedded data simulation software module, receives the low-orbit navigation signal simulation data, and completes the baseband signal and RF signal generation.

[0045] The time-frequency synchronization and branching module receives real navigation signals from space, provides ephemeris files and time, and provides PPS and 10MHz time reference to the hardware platform to complete the time synchronization between the low-orbit navigation simulator and the space navigation signal.

[0046] The power module provides power for the low-orbit navigation simulator.

[0047] Figure 2 It is a design diagram of the embedded data simulation software module of the present invention.

[0048] The embedded data simulation software module runs on the embedded platform, generates low-orbit navigation signal simulation data, and interacts with the signal generation module.

[0049] The embedded data simulation software module needs to complete the data simulation function of the low-orbit navigation simulator, realize the navigation system constellation simulation, error model simulation, pseudo-range observation simulation, message framing, user trajectory simulation, channel control and monitoring equipment operation status.

[0050] Figure 3 It is a design diagram of the signal generating module of the present invention.

[0051] The signal generation module is implemented based on FPGA and DA, and mainly generates the baseband signal and RF signal of the low-orbit navigation signal;

[0052] Baseband signal generation includes code NCO design, carrier NCO design, navigation message generation design, signal modulation design, and generates intermediate frequency baseband signals;

[0053] RF signal generation includes DA digital-to-analog conversion design and signal frequency conversion design to complete the processing of digital baseband signals to analog RF signals.

[0054] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A low-orbit navigation simulator based on embedded data simulation software, characterized in that: It includes embedded data simulation software module, signal generation module and time-frequency synchronization and branching module; The embedded data simulation software module is used to complete the data simulation function of the low-orbit navigation simulator; The signal generation module is used to complete the generation of baseband signals and radio frequency signals; The time-frequency synchronization and branching module is used to receive real space navigation signals and provide ephemeris files and time for the data simulation module. It also provides PPS and 10MHz time reference to complete the time synchronization between the low-orbit navigation simulator and the space navigation signal. The embedded data simulation software module receives the time and position information from the signal generation module as the simulation time and position reference, and simulates the low-orbit navigation signal that is synchronized with the real navigation signal in space based on the received real-time ephemeris data. The signal processing module generates baseband signals and radio frequency signals through the simulated navigation signals.

2. A low-orbit navigation simulator based on embedded data simulation software according to claim 1, characterized in that: The embedded data simulation software module completes the low-orbit navigation system constellation simulation and error model simulation at the current moment, and completes the user trajectory simulation according to the simulation position and speed set by the low-orbit navigation simulator; according to the current user trajectory, the navigation system's space constellation simulation data and the space error model simulation data, completes the pseudo-range observation simulation calculation and message framing, and sends the pseudo-range observation and the framed message to the signal processing module.

3. A low-orbit navigation simulator based on embedded data simulation software according to claim 2, characterized in that: The baseband signal generation process of the signal generation module is as follows: After receiving the pseudo-range observation and message frame from the data simulation module, the pseudo-range observation drives the code NCO and the carrier NCO to generate pseudo-code and carrier. The message frame is transmitted to the message analysis unit, and the message detection at the current moment is extracted according to the current simulation time. After the pseudo code, carrier and message frame are digitally modulated, a baseband digital simulation signal is generated.

4. A low-orbit navigation simulator based on embedded data simulation software according to claim 1, characterized in that: The radio frequency signal generation process of the signal generation module is specifically as follows: After the signal generation module generates a digital baseband signal from FPGA, it sends the digital baseband signal to DA, completes the local oscillator configuration of DA according to the simulated frequency point, and generates a spread spectrum analog navigation signal of the corresponding frequency point.

5. A low-orbit navigation simulator based on embedded data simulation software according to claim 1, characterized in that: The time-frequency synchronization and branching module is equipped with a timing receiver. After an external receiving antenna is connected, it receives the navigation signal from space, outputs synchronized PSS and 10MHz signals based on the real navigation signal in space, and performs timing on the high-precision clock crystal oscillator of the time-frequency synchronization and branching module, so that the PSS and 10MHz output by the crystal oscillator are synchronized with the real signal in space.

6. A low-orbit navigation simulator based on embedded data simulation software according to claim 1, characterized in that: The time-frequency synchronization and branching module is configured with a high-precision clock crystal oscillator. After the device is powered on and started, the clock crystal oscillator will maintain a local PPS and 10MHz clock for normal startup and initialization of the device; the time-frequency synchronization and branching module is configured with a clock processing board to complete the branching of the PPS and 10MHz clock, and output the branched clock to the signal generation module to ensure the synchronization of the simulated low-orbit navigation signal and the space navigation signal.

7. A low-orbit navigation simulator based on embedded data simulation software according to claim 1, characterized in that: The signal processing module reports the simulation status to the software, monitors the current signal simulation frequency, signal power and number of visible satellites, and can control the signal simulation frequency, transmission power and number of channels according to usage requirements.

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