CN107066693B - Multichannel multi-target satellite-borne AIS reconnaissance signal simulation system - Google Patents

Multichannel multi-target satellite-borne AIS reconnaissance signal simulation system Download PDF

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CN107066693B
CN107066693B CN201710148410.4A CN201710148410A CN107066693B CN 107066693 B CN107066693 B CN 107066693B CN 201710148410 A CN201710148410 A CN 201710148410A CN 107066693 B CN107066693 B CN 107066693B
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ship
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单珍
金灵芝
周平
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National University of Defense Technology
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Changsha Dingduan Electronic Technology Co ltd
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    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
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Abstract

The invention relates to a multi-channel multi-target satellite-borne AIS reconnaissance signal simulation system. The system is a system for simulating the dynamic AIS signals of multi-target aliasing received by the satellite-borne AIS multi-channel reconnaissance system during on-orbit operation. The system generates two paths of signals, and all filtering and frequency conversion of the four channels of AIS signals are all calculated in a full digital mode, the consistency among the channels is good, the signal stray is small, and the harmonic component is small; the clock sampling rate is high, the time resolution of the generated AIS signal is high, and the control precision of the time delay can reach about 8us magnitude; the method can generate a plurality of AIS targets, has long continuous simulation time (more than five minutes), and can simulate any scene of 0-10000 ships in the same field of view. The AIS radio frequency signal with dynamically changed multi-target aliasing such as Doppler frequency shift, amplitude fluctuation and the like caused by relative motion can be received during vividly generated satellite-borne reconnaissance.

Description

Multichannel multi-target satellite-borne AIS reconnaissance signal simulation system
Technical Field
The invention belongs to the technical field of signal simulation and emulation, relates to a signal simulation system, and particularly relates to a multi-channel multi-target simulation transposition for ship Automatic Identification System (AIS) signals transmitted by various ships on a satellite reconnaissance sea surface.
Background
An Automatic Identification System (AIS) for ships is a System that automatically broadcasts and receives dynamic and static information of ships in a self-organizing time division multiple access manner in a very high frequency mobile frequency band at sea so as to realize Identification, monitoring and communication. At present, the short message interactive navigation system is widely installed on various large, medium and small ships to realize functions of transmitting and receiving short messages on the ship shore and between ships, interacting messages, navigating and avoiding collision and the like. In order to realize effective monitoring and management of ships, a satellite-borne ship automatic identification system is developed in more than ten years, ships in the global sea area can be effectively monitored throughout the day and in a large view field, and information situation display and early warning of ships in peripheral sea areas and even the global sea area in China are realized.
As the AIS system adopts a self-organizing time division multiple access (SOTDMA) communication system specified in ITU-R M.1371-5 technical specification, the simultaneous transmission of signals by ships among different cells causes the aliasing of signals at a satellite receiving end. Besides, the satellite-borne AIS reception differs from the ship-borne AIS reception in the following points: firstly, Doppler frequency shift exists between aliasing signal sources due to relative high-speed motion of a satellite and a ship; secondly, power difference exists between the received aliasing signal sources due to power attenuation of different distances; thirdly, time delay exists between the received aliasing signal sources due to different positions of the ship and the receiving antenna. Therefore, the time domain and frequency domain multiple aliasing, Doppler frequency shift and amplitude fluctuation phenomena of a plurality of ship cell signals can be generated during satellite reconnaissance, and the performance of the satellite-borne AIS reconnaissance system is seriously influenced. At present, most satellite-borne AIS systems such as two experimental satellites with satellite-borne AIS receiving and processing functions launched in 2010 in norway: AISSat-1 and NORAIS, etc., each have one or more receive channels. After the satellite transmits the satellite to operate on orbit, some standard scenes cannot be found to verify and calibrate all technical indexes of the satellite-borne AIS system, and in order to accurately and quantitatively evaluate the performance of the satellite-borne AIS system, a special multi-channel multi-target satellite-borne AIS reconnaissance signal simulator needs to be developed.
Chinese patent application 201610786782.5 proposes an AIS data simulation method in an ocean electronic application system, but the method is mainly used for simulating data of a single AIS target, cannot generate dynamically-changing AIS radio-frequency signals with doppler shift, amplitude fluctuation and the like caused by relative motion during satellite-borne reconnaissance, and cannot generate multi-target satellite-borne AIS reconnaissance multi-channel receiver coherent aliasing signals which are just the most critical factors affecting the performance of the satellite-borne AIS reconnaissance system.
Disclosure of Invention
The invention aims to provide a system for simulating a dynamic AIS signal which receives multi-target aliasing during on-orbit operation of a satellite-borne AIS multi-channel reconnaissance system.
The invention has the technical scheme that the multichannel multi-target satellite-borne AIS reconnaissance signal simulation system comprises a CPCI industrial personal computer (or a common industrial personal computer or a general computer), a signal generation card and two DAC daughter cards,
the CPCI industrial personal computer comprises a computer mainboard, a case, a power supply, a keyboard, a mouse and a display, wherein scene data generation software and data loading software run on the CPCI industrial personal computer;
the scene data generation software is application software running on the CPCI industrial personal computer and used for generating a multi-target multi-channel AIS baseband signal data file received by a satellite according to a user-set scene simulation. For transmitting the AIS signal scenario by a plurality of vessels on the sea surface, since each vessel transmits according to the sodtdma scheme, the simulation can be performed according to the following steps: reading a satellite ephemeris file containing satellite positions and speeds selected by a user, and randomly generating the positions, speeds, navigation states and the like of K ships on the sea surface of a satellite visual field; secondly, the first ship decides the emission interval Tr according to the technical specification of ITU-R M.1371-5 and the navigation speed and the state of the first ship, randomly selects a time slot moment in the emission interval Tr for emission, and then sequentially determines all time slot emission moments behind the first ship according to the emission interval and the first emission time slot; thirdly, judging whether a subsequent kth ship is in the range of the view field cell or not; step four, the kth ship randomly selects a first transmitting time slot and determines a later time slot according to a transmitting interval; fifthly, judging whether all the transmitting time slots of the kth ship conflict with the allocated time slots of the ship in the field-of-view cell; if not, the next ship is generated, and if so, the fourth step is returned again, …, until no conflict exists; and sixthly, judging whether the time slot allocation of all the ships is finished, namely whether k is larger than N, if not, repeating the third step, and if so, recording the launching time and the occupied time slot number of each ship.
Generating AIS data of the time slot according to the time slot number and the transmitting time, wherein the specific process is as follows:
according to the time slot time t corresponding to the ith time slot number of the kth shipk,iAnd ITU-R M.1371-4 specification, generating a sampling rate fs1GMSK modulated AIS baseband signal at 38.4kHz
Figure GDA0002374769600000021
Wherein
Figure GDA0002374769600000022
Express get and put fortuneAnd (4) calculating. Multiplying the signal data of the plurality of time slots by the ship-borne transmitting antenna gain, the satellite-borne receiving antenna gain and the Doppler frequency shift, and then performing time domain superposition according to the corresponding time of each time slot to obtain satellite-borne AIS baseband signal data:
Figure GDA0002374769600000023
the above formula C is an amplitude normalization factor, wherein Prk,iFor the received signal power of each time slot, fdk,iFor Doppler shift of each time slot, τk,iFor the time delay of each time slot, phik,iFor phase differences between channels of each time slot, IkIs the slot number.
The way each amount is calculated is as follows:
a) calculation of power (amplitude)
In the formula (1), Prk,iFor receiving the signal power, the power is calculated as follows according to the scout equation
Figure GDA0002374769600000031
(2) In the formula PTλ is the AIS signal wavelength, G, for the known AIS transmission power on board the shiptk,iFor an onboard AIS transmitting antenna at tk,iThe gain in the pointing direction of the satellite at the moment, the empirical formula for the gain of a typical shipborne AIS antenna is as follows
Figure GDA0002374769600000032
Wherein theta ist,iThe local elevation angle of the ship where the satellite is located is calculated by the formula
Figure GDA0002374769600000033
Wherein xsk,i＝[xsk,i,ysk,i,zsk,i]TAnd xtk,i＝[xtk,i,ytk,i,ztk,i]TAt t for the satellite and the k-th vessel, respectivelyk,iThree-dimensional position under the earth-center-earth-fixation (ECF) coordinate system at moment, "| | · |" represents 2 norm, rk,iDistance to satellite and ship:
rk,i＝||xsk,i-xtk,i|| (5)
(6) in the formula Grk,iFor satellite-borne receiving antennas at tk,iThe gain in the pointing direction of the kth vessel at the moment is typically calculated empirically as
Figure GDA0002374769600000034
Wherein u isak,iThe pointing unit vector for the satellite-borne antenna in the ECF coordinate system can be known in advance and assumed to be fixed in the satellite coordinate system, generally in terms of satellite attitude and installation.
b) Calculation of Doppler shift
(7) In the formula fdk,iFor Doppler shift, the calculation formula is as follows
Figure GDA0002374769600000035
Figure GDA0002374769600000036
Is the relative movement speed of the satellite and the ship, lambdak,iIs the transmission signal wavelength.
c) Calculation of phase difference for dual channel antennas
Because the connection direction of the two-channel antenna is consistent with the satellite motion direction, the phase difference between the two-channel antenna can be calculated as
Figure GDA0002374769600000041
Wherein
Figure GDA0002374769600000042
d is the distance between the channels, vsk,iIs a horizontal component of velocity, vsi,iThe velocity vertical component.
d) Calculation of signal time delay
According to the distance from each target to the satellite, the signal time delay of each time slot signal can be calculated as
Figure GDA0002374769600000043
Wherein c is the speed of light
Parameters of each time slot calculated in the formula (1) can be generated according to the formulas (2) to (9), multi-target superposed signal waveform data can be calculated through the formula (1), and the signal waveform data is written into a binary file to a disk file, so that a baseband signal data file can be obtained.
The data loading software is another application software running on the CPCI industrial personal computer, and has the main function of selecting a data file generated by the scene and baseband signal generation software, downloading the data file to the signal generation motherboard through the CPCI interface, and playing the waveform of the generated data file. Since the baseband signal data file generated by the scene data generation software is stored on the disk, the same or different data files can be repeatedly played through the data loading software for repeatedly checking and verifying the performance of the satellite borne AIS reconnaissance system.
The signal generating card is a CPCI card (or PCI card), and the signal generating board is a CPCI card based on a 66MHz and 64-bit PCI bus and is used for connecting a DAC daughter card and completing part of digital signal processing functions. The carrier plate comprises a clock circuit, a power supply module, a signal processing module, a memory, a CPCI bus control module and the like, and various interfaces are externally expanded through the connection of the FPGA and the expansion slot. The bottom board receives signal sampling points or data sent from the daughter board, and partial parameters are processed in the FPGA and DSP chips in real time or stored in a DDR memory on the board for post-processing. And the processing result or the original data is sent out to the industrial personal computer for display or processing through a 64-bit CPCI bus. The signal generation card processing module comprises an ADSP-TS201S DSP chip of ADI company and two XC5VSX95T FPGA chips of Xilinx company. The DSP is connected with the FPGAs through a data bus, and a definable high-speed interconnection bus is arranged between the two FPGAs, so that direct data interaction between the FPGAs is realized; the FPGA on the bottom plate is connected with four external data expansion interfaces, and the exchange with external data is realized in a back carrier plate mode; the DSP expansion interface is provided, and the FPGA, the DSP and the memory are added in a back carrier board mode, so that the resources and the processing capacity of the board card are expanded; the FPGA is connected with the CPCI expansion slot J5 through a custom bus, and is used for realizing custom connection with other CPCI board cards. All the custom buses can be defined as LVDS differential signal lines or LVCMOS single-ended signal lines, and the design of the FPGA is depended on; the clock synthesis module on the board can set parameters through the DSP to acquire the required clock frequency and phase relation.
The DAC daughter card is connected to the data processing carrier plate in a high-speed connector interface mode and comprises a DAC chip, and data generated by the FPGA can be directly output AIS radio frequency analog signals through digital-to-analog conversion (D/A). The DA converter is a 16-bit DAC chip of a DAC5687 model. The working clock of the chip is 500MHz, and the dynamic range of the chip is more than 80 dB. The carrier board provides power and clock for the daughter board through the high-speed connector, and transmits the signal sampling points to the DAC module to realize digital-to-analog conversion.
Considering that the central frequencies of different AIS channels are 161.975MHz/162.025MHz (87B/88B channel) and 156.775MHz/156.825MHz (75/76 channel), respectively, the signal bandwidths are 25kHz, the difference between 161.975MHz/162.025MHz signals is 50kHz, and the difference between 156.775MHz/156.825MHz is 50kHz, the scene data generation software of the present invention generates the sampling rate of baseband signal data, and the typical value is 122.07kHz, so that the simultaneous simulation generation of two AIS signals 161.975MHz/162.025MHz or 156.775MHz/156.825MHz can be realized without distortion.
In order to enable simultaneous simulation of the AIS channel signals described above on the signal generating card, techniques of signal waveform multi-level zero-padding interpolation and three-level vector modulation may be employed. Namely, the scene data generation software generates baseband data of two channels of 161.975MHz/162.025MHz and two channels of 156.775MHz/156.825MHz simultaneously when generating a data file, the scene data generation software outputs baseband signal data with fs being 122.07kHz, and then the baseband signal data is loaded to an FPGA on a signal generation card to perform zero padding interpolation according to multiple stages, 4096 times of interpolation is obtained in total and then up-conversion is performed, so that direct radio frequency simulation of AIS signals is realized.
In order to reduce the requirement on FPGA resources, data of an 87B/88B channel is generated on the same I/Q data with the sampling rate fs being 122.07kHz, and is modulated to a digital intermediate frequency of 2.6MHz by a complex carrier after being subjected to two-stage 8-time interpolation and low-pass filtering and then being subjected to 8 × 8-time 64-time interpolation filtering; data of 75/76 channels are generated on another I/Q data with fs being 122.07kHz, the data are subjected to interpolation filtering by two stages of 8 times and low-pass filtering by 64 times, then the data are modulated to a digital intermediate frequency with-2.6 MHz by a complex carrier, the two complex carriers are synthesized to a complex carrier with a sampling rate of 7.8125MHz, then the complex carrier is subjected to 8 times, 4 times, 2 times of interpolation and low-pass filtering by three stages to form 8 multiplied by 4 multiplied by 2 being 64 times of interpolation filtering, a zero intermediate frequency I/Q signal sampled by 500MHz is generated, the zero intermediate frequency I/Q signal is modulated to a carrier with 159.4MHz by a vector to form two paths of digital signals sampled by 500MHz of 4 channels/paths, and D/A chips on two DAC daughter cards are controlled by FPGA to perform digital-analog conversion, and a two-channel dynamic satellite-borne AIS signal required by the satellite AIS detection equipment is generated.
The invention can achieve the following beneficial effects:
1. the system can receive the AIS radio frequency signal with dynamically changed multi-target aliasing such as Doppler frequency shift, amplitude fluctuation and the like caused by relative motion during vividly generated satellite-borne reconnaissance;
2. the system generates two paths of signals, and all filtering and frequency conversion of the four channels of AIS signals are all calculated in a full digital mode, the consistency among the channels is good, the signal stray is small, and the harmonic component is small;
3. the clock sampling rate of the invention is high, the time resolution of the generated AIS signal is high, and the control precision of the time delay can reach about 8us magnitude;
4. the method can generate a large number of AIS targets and long continuous simulation time (more than five minutes), and can simulate any scene of 0-10000 ships in the same field of view.
Drawings
FIG. 1: the multichannel multi-target satellite-borne AIS reconnaissance signal simulator system disclosed by the invention forms a block diagram;
FIG. 2: a multi-channel multi-target satellite-borne AIS reconnaissance signal simulator work flow diagram;
FIG. 3: the connection block diagram of the hardware module of the signal generation card;
FIG. 4: a hardware module of the DAC daughter card forms a connection block diagram;
FIG. 5: a single-channel signal waveform multi-level zero-padding interpolation and three-level vector modulation functional block diagram;
FIG. 6: a two-dimensional projection diagram of a typical satellite-borne AIS reconnaissance simulation scene;
FIG. 7: an AIS baseband signal waveform diagram of multi-target aliasing.
Detailed Description
The invention is further described below with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1, the proposed multi-channel multi-target satellite-borne AIS reconnaissance signal simulator is composed of hardware such as a CPCI industrial personal computer (or a common industrial personal computer, a general purpose computer), a signal generation card, two DAC sub-cards and software such as scene data generation software and data loading software which run on the CPCI industrial personal computer. The scene data generation software generates a baseband signal data file according to user setting, the data loading software loads the baseband signal data file and sends the baseband signal data to the signal generation card through a CPCI bus, the signal generation card is provided with an FPGA, a DDR memory, a DSP and other computing memory devices, the baseband signal is subjected to multi-level zero padding interpolation and three-level vector modulation to generate two paths of 500MHz sampled AIS radio frequency digital signal data, the signal generation card is connected with the two DAC daughter cards through a high-speed connector and sends the AIS radio frequency digital signal data to the DAC daughter cards, and the D/A devices on the DAC daughter cards convert the AIS radio frequency digital signal data into analog signals to be output.
As shown in fig. 2, after a user starts up, the scene and baseband signal data generation software is started, after setting scene parameters, a click is performed to start simulation, the software starts to calculate a visual range according to a set satellite motion scene, generates a plurality of ship targets in the visual range, performs SOTDMA time slot simulation, generates AIS signals according to a time slot specified by each target, superposes multi-target signals, generates baseband signal data with multiple superposed targets, stores the baseband signal data in a disk, and loads corresponding signal data files through signal loading software to output. The signal loading software can also select any historically generated baseband signal data file to play or repeatedly play back.
As shown in fig. 3, the signal generation card is a CPCI card based on a 66MHz, 64-bit PCI bus, and is used to connect with a DAC daughter card and perform digital signal processing functions such as multi-level zero-padding interpolation, filtering, and three-level vector modulation. The carrier plate comprises a clock circuit, a power supply module, a signal processing module, a memory, a CPCI bus control module and the like, and various interfaces are externally expanded through the connection of the FPGA and the expansion slot. The bottom board receives signal sampling points or data sent from the daughter board, and partial parameters are processed in the FPGA and DSP chips in real time or stored in a DDR memory on the board for post-processing. And the processing result or the original data is sent out to the industrial personal computer for display or processing through a 64-bit CPCI bus. The main processing modules on the board are a DSP and two FPGAs, the DSP type selection is ADSP-TS201S, and the FPGA type selection is XC5VSX 95T. The DSP is connected with the FPGAs through a data bus, and a definable high-speed interconnection bus is arranged between the two FPGAs, so that direct data interaction between the FPGAs is realized; the FPGA on the bottom plate is connected with four external data expansion interfaces, and the exchange with external data is realized in a back carrier plate mode; the DSP expansion interface is provided, and the FPGA, the DSP and the memory are added in a back carrier board mode, so that the resources and the processing capacity of the board card are expanded; the FPGA is connected with the CPCI expansion slot J5 through a custom bus, and is used for realizing custom connection with other CPCI board cards. All the custom buses can be defined as LVDS differential signal lines or LVCMOS single-ended signal lines, and the design of the FPGA is depended on; the clock synthesis module on the board can set parameters through the DSP to acquire the required clock frequency and phase relation.
Fig. 4 shows a block diagram of a DAC daughter card design module, where the DAC daughter card is connected to a data processing carrier board in the form of a high-speed connector interface. The carrier board provides power and clock for the daughter board through the high-speed connector, and transmits the signal sampling point to the DAC module to realize digital-analog conversion, and then carries out smooth filtering through the low-pass filter. The DA converter is a 16-bit DAC chip of a DAC5687 model. The working clock of the chip is 500MHz, and the bandwidth of the low-pass filter can reach 170MHz at most.
As shown in fig. 5, in order to enable simultaneous simulation of the AIS channel signals described above on the signal generating card, a technique of multi-stage zero-padding interpolation and three-stage vector modulation of the signal waveform as shown in the figure is employed. Namely, the scene data generation software generates baseband data of two channels of 161.975MHz/162.025MHz and two channels of 156.775MHz/156.825MHz simultaneously when generating a data file, the sampling rate fs of the baseband data is 122.07kHz, and then the baseband data is loaded to an FPGA on a signal generation card to perform multi-stage zero-filling interpolation and low-pass filtering, 4096 times of interpolation is obtained in total, and then up-conversion is performed to realize direct radio frequency simulation of AIS signals. In order to reduce the requirement of FPGA resources, data of an 87B/88B channel is modulated on the same I/Q data with the sampling rate fs being 122.07kHz, a digital I/Q signal with the sampling rate of 7.8125MHz is formed after two-stage 8-time interpolation and low-pass filtering are carried out and 64-time interpolation filtering is carried out, and the digital I/Q signal is modulated to a digital intermediate frequency of 2.6MHz by a complex carrier; the data of 75/76 channels is modulated on another I/Q data with fs being 122.07kHz, and is modulated to a digital intermediate frequency of-2.6 MHz by a complex carrier after being filtered by two-stage 8-time interpolation and low-pass filtering and 64-time interpolation. Adding the two complex carriers, synthesizing the two complex carriers into a complex carrier with a sampling rate of 7.8125MHz, performing three-level 8-time, 4-time, 2-time interpolation and low-pass filtering to form 8 multiplied by 4 multiplied by 2 which is 64 times of interpolation filtering, generating a zero intermediate frequency I/Q signal sampled by 500MHz, modulating the signal to the 159.4MHz carrier through a vector to form two paths of digital signals sampled by 500MHz of 4 channels/paths, controlling D/A chips on two paths of DAC daughter cards to perform digital-to-analog conversion through an FPGA (field programmable gate array), and generating a two-channel dynamic satellite-borne AIS signal required by the inspection satellite AIS reconnaissance equipment.
As shown in fig. 6, a certain simulation sets an AIS satellite height of 500km and a startup time of 300s, which is assumed to set 4500 vessels uniformly distributed on the ocean in the coverage field of satellite reconnaissance in the reconnaissance range of the east pacific region, and is used for simulating AIS radio frequency signals with dynamically-changing multi-target aliasing, such as doppler shift, amplitude fluctuation and the like caused by relative motion, received by the satellite when all the vessels perform satellite-borne reconnaissance.
As shown in fig. 7, the AIS baseband signals generated by the scene data generation software for the scene of fig. 6 are dynamically superimposed with dynamically changing multi-target aliased AIS baseband signals such as doppler shift, amplitude fluctuation, etc., and the sampling rate of the baseband signals is 122.07 MHz.

Claims (3)

1. A multi-channel multi-target satellite-borne AIS reconnaissance signal simulation system comprises a CPCI industrial personal computer, a signal generation card and two DAC daughter cards,
the CPCI industrial personal computer runs scene data generation software and data loading software and is characterized in that,
the scene data generation software generates a multi-target multi-channel AIS baseband signal data file received by a satellite according to the scene simulation set by a user, and for a plurality of ships on the sea surface to transmit AIS signal scenes, the simulation is carried out according to the following steps: reading a satellite ephemeris file containing satellite positions and speeds selected by a user, and randomly generating the positions, speeds and navigation states of K ships on the sea surface of a satellite visual field; secondly, the first ship decides the emission interval Tr according to the technical specification of ITU-R M.1371-5 and the navigation speed and the state of the first ship, randomly selects a time slot moment in the emission interval Tr for emission, and then sequentially determines all time slot emission moments behind the first ship according to the emission interval and the first emission time slot; thirdly, judging whether a subsequent kth ship is in the range of the view field cell or not; step four, the kth ship randomly selects a first transmitting time slot and determines a later time slot according to a transmitting interval; fifthly, judging whether all the transmitting time slots of the kth ship conflict with the allocated time slots of the ship in the field-of-view cell; if not, generating the next ship, and if so, returning to the fourth step again until no conflict exists; sixthly, judging whether the time slot allocation of all ships is finished, namely whether K is larger than K, if not, repeating the third step, if so, recording the emission time and the occupied time slot number of each ship, and generating AIS data of the time slot according to the time slot numbers and the emission time;
the data loading software selects a data file generated by the scene and baseband signal generating software, and downloads the data file to the signal generating motherboard for playing the waveform of the generated data file.
2. The multi-channel multi-target satellite-borne AIS (automatic identification system) reconnaissance signal simulation system of claim 1, wherein the signal generation card is a CPCI (compact peripheral component interconnect) card based on a 66MHz 64-bit PCI (peripheral component interconnect) bus, and is used for connecting a DAC (digital-to-analog converter) daughter card and completing partial digital signal processing functions.
3. The multi-channel multi-target satellite-borne AIS reconnaissance signal simulation system of claim 1, wherein AIS data of the time slot is generated according to the time slot number and the transmission time, and the specific process is as follows:
according to the time slot time t corresponding to the ith time slot number of the kth shipk,iAnd ITU-R M.1371-5 specification, generating a sample rate fs1GMSK modulated AIS baseband signal at 38.4kHz
Figure FDA0002393569990000011
Wherein
Figure FDA0002393569990000012
And expressing rounding operation, multiplying the signal data of a plurality of time slots by the ship-borne transmitting antenna gain, the satellite-borne receiving antenna gain and the Doppler frequency shift, and then performing time domain superposition according to the corresponding moment of each time slot to obtain satellite-borne AIS baseband signal data:
Figure FDA0002393569990000013
the above formula C is an amplitude normalization factor, wherein Prk,iFor the received signal power of each time slot, fdk,iFor Doppler shift of each time slot, τk,iFor each oneTime delay of one time slot, phik,iFor phase differences between channels of each time slot, IkIs a time slot serial number;
the way each amount is calculated is as follows:
a) calculation of power
In the formula (1), Prk,iFor receiving the signal power, the power is calculated as follows according to the scout equation
Figure FDA0002393569990000021
(2) In the formula PTλ is the AIS signal wavelength, G, for the known AIS transmission power on board the shiptk,iFor an onboard AIS transmitting antenna at tk,iThe gain in the pointing direction of the satellite at the moment, the empirical formula for the gain of a typical shipborne AIS antenna is as follows
Figure FDA0002393569990000022
Wherein theta ist,iThe local elevation angle of the ship where the satellite is located is calculated by the formula
Figure FDA0002393569990000023
Wherein xsk,i＝[xsk,i,ysk,i,zsk,i]TAnd xtk,i＝[xtk,i,ytk,i,ztk,i]TAt t for the satellite and the k-th vessel, respectivelyk,iThe three-dimensional position under the earth's center and earth's solid coordinate system at the moment, | | | · | | represents a 2 norm, rk,iDistance to satellite and ship:
rk,i＝||xsk,i-xtk,i|| (5)
(6) in the formula Grk,iFor satellite-borne receiving antennas at tk,iThe gain in the pointing direction of the kth vessel at the moment is typically calculated empirically as
Figure FDA0002393569990000024
Wherein u isak,iThe pointing unit vector of the satellite-borne antenna in the earth-centered earth-fixed coordinate system can be known in advance according to the satellite attitude and installation and is assumed to be fixed in the satellite coordinate system,
b) calculation of Doppler shift
(7) In the formula fdk,iFor Doppler shift, the calculation formula is as follows
Figure FDA0002393569990000031
Figure FDA0002393569990000032
Is the relative velocity component of the ship and the satellite at time T, lambdak,iIs the signal wavelength;
c) calculation of phase difference for dual channel antennas
Because the connection direction of the two-channel antenna is consistent with the satellite motion direction, the phase difference between the two-channel antenna is calculated as
Figure FDA0002393569990000033
Wherein
Figure FDA0002393569990000034
d is the distance between two channels, vsk,iIs a horizontal velocity component, vsi,iIs the vertical velocity component;
d) calculation of signal time delay
According to the distance from each target to the satellite, calculating the signal time delay of each time slot signal as
Figure FDA0002393569990000035
Wherein c is the speed of light;
and (3) generating a parameter of each time slot in the formula (1) according to the formulas (2) to (9), calculating signal waveform data of multi-target superposition through the formula (1), writing the signal waveform data into a binary file to a disk file, and obtaining a baseband signal data file.
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* Cited by examiner, † Cited by third party
Title
星载AIS系统信号模拟源的仿真实现;栗霖雲等;《无线电工程》;20140105;第44卷(第1期);第62-64页 *

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