CN109547161B

CN109547161B - ADS-B multichannel signal generation method

Info

Publication number: CN109547161B
Application number: CN201811399243.1A
Authority: CN
Inventors: 刘光伦
Original assignee: Sichuan Jiuzhou Electric Group Co Ltd
Current assignee: Sichuan Jiuzhou Electric Group Co Ltd
Priority date: 2018-11-22
Filing date: 2018-11-22
Publication date: 2020-06-16
Anticipated expiration: 2038-11-22
Also published as: CN109547161A

Abstract

The invention relates to a method for generating ADS-B multichannel signals, which belongs to the technical field of aviation and comprises the steps that an upper computer acquires multi-channel message data and determines an ADS-B message output scheme; processing the multi-channel message data into a multi-channel transmission composite frame and sending the multi-channel transmission composite frame to a terminal machine; the terminal receives the multi-channel transmission composite frame data, and forms a multi-channel radio frequency signal to be transmitted through the antenna after data analysis, modulation, amplification and multi-channel delay control. The invention can generate ADS-B multi-path signals and simulate the characteristics of multi-path, interweaving and the like generated when the ADS-B signals are transmitted in the air.

Description

ADS-B multichannel signal generation method

Technical Field

The invention relates to the technical field of aviation, in particular to an ADS-B multi-channel signal generation method.

Background

ADS-B is one of ADS technologies, is the monitoring equipment with the highest precision at present, plays an important role in conflict resolution and interval allocation, ensures a new means with high flight safety and high efficiency, and is widely applied to air traffic condition monitoring, collision avoidance, airport scene monitoring and the like. At present, aiming at the research on the generation of ADS-B signals, a plurality of single-path signals are output; with the overall deployment of ADS-B, the requirement on the generation technology of multi-channel ADS-B signals is more and more, but corresponding technologies and equipment are lacked.

Disclosure of Invention

In view of the above analysis, the present invention is directed to provide a method for generating an ADS-B multi-channel signal, which generates an ADS-B multi-channel signal and simulates the characteristics of multi-channel signals, interleaving, etc. generated when the ADS-B signal is transmitted in the air.

The purpose of the invention is mainly realized by the following technical scheme:

an ADS-B multichannel signal generation method comprises the following steps:

the upper computer acquires multi-channel message data and determines an ADS-B message output scheme;

processing the multi-channel message data into a multi-channel transmission composite frame according to the output scheme of the message, and sending the multi-channel transmission composite frame to a terminal;

the terminal receives the multi-channel transmission composite frame data, and forms a multi-channel radio frequency signal to be transmitted through the antenna after data analysis, modulation, amplification and multi-channel delay control.

Further, the multi-channel transmission composite frame comprises a synchronization header, a channel enable field, a delay field, a frame data segment and a CRC;

the synchronization header comprises 2 bytes;

the channel enable field comprises N BITs; n is the number of output channels determined in the ADS-B message output scheme; each channel is enabled to be 1BIT,0 represents channel prohibition, and 1 represents channel enable output;

the delay field comprises N bytes; wherein, the bytes correspond to the output channels and represent the delay time of N output channels;

the frame data segment comprises N data fields; each frame data field is ADS-B message data after each output channel is coded;

CRC is a cyclic redundancy check code, which is a check code of the entire transmission frame.

Further, the processing procedure of the terminal includes:

1) after receiving the data stream of the multi-channel transmission composite frame, firstly detecting a synchronous head, and after finding the synchronous head, carrying out data verification on the transmission frame;

2) after the data is checked to be correct, CRC (cyclic redundancy check) and analysis are carried out on ADS-B message data streams of all channels;

3) respectively extracting frame data, an enable bit and a delay size of each channel, and performing PPM (pulse position modulation) and delay control to generate ADS-B baseband signals of each channel;

4) and modulating the ADS-B baseband signals of all channels onto 1090MHz carrier waves, amplifying and transmitting by an antenna.

Further, the delay control comprises that a constant temperature crystal oscillator is adopted on the terminal machine to provide a source clock for the PLL management chip; the PLL management chip outputs a stable clock to the FPGA of the terminal; the FPGA controls the time delay of each channel through frequency division.

Further, the method for displaying the map comprises the following steps:

the upper computer obtains GNSS information, performs initial position positioning on position information contained in the obtained multi-channel message data, and displays the position information on a GIS map;

after the upper computer transmits data, the generated flight track data are synchronously displayed on a GIS map;

important airplane parameter data is displayed in a form of a satellite signboard on a map in a superposition mode in real time.

An ADS-B multichannel signal generation method comprises an upper computer and a terminal; the upper computer is connected with the terminal through a serial interface;

the upper computer is used for acquiring multi-path message data and determining an ADS-B message output scheme; processing the multi-channel message data into a multi-channel transmission composite frame according to the output scheme of the message, and transmitting the multi-channel transmission composite frame to a terminal through a serial interface;

and the terminal is used for receiving the multi-channel transmission composite frame data, and forming a plurality of paths of radio frequency signals to be transmitted through the antenna after carrying out data analysis, modulation, amplification and multi-channel delay control on the composite frame.

Furthermore, a message data acquisition module, a message output scheme generation module, a message data coding module, a multi-channel transmission composite frame generation module and a serial port module are arranged in the upper computer;

the message data acquisition module acquires message data of a plurality of channels, including the number of airplanes, the working mode, the secondary code setting, the flight identification code setting, the S mode address setting, the maximum flight speed and the initial longitude and latitude of the airplane;

the message output scheme generating module is used for setting a message output scheme according to the acquired message data;

the message data coding module is used for coding the multi-channel message data according to the data types;

the multi-channel transmission synthesis frame generation module synthesizes multi-channel transmission synthesis frame data according to a set message output scheme and the coded message data;

and the serial port module converts the multi-channel transmission composite frame into a serial data format and sends the serial data format to the terminal through a serial port.

Furthermore, the terminal comprises an interface module, an FPGA module, a multi-channel radio frequency output module, an antenna and a state monitoring module;

the interface module is connected with a serial port module of the upper computer and used for receiving serial data sent by the upper computer as serial data and then sending the serial data to the FPGA module;

the FPGA module is used for analyzing frame data after CRC (cyclic redundancy check) is carried out on multi-channel transmission synthesis frame data transmitted by the interface module, extracting frame data, enabling bits and delay size of each channel, and then carrying out PPM (pulse position modulation) on the frame data to be sent to the multi-channel radio frequency output module;

the multi-path radio frequency output module is used for modulating the multi-path PPM modulation signals output by the FPGA module to 1090MHz carrier waves and then amplifying the multi-path PPM modulation signals;

the antenna is connected with the multi-path radio frequency output module and used for sending out the multi-path data after radio frequency amplification;

and the state monitoring module is used for monitoring information including the operating current and power consumption of the terminal machine, the sending rate and the sending progress of the message and the sending frame number of the message.

Furthermore, the FPGA module adopts a constant temperature crystal oscillator to provide a source clock for the PLL management chip, the PLL management chip outputs the clock to the control module in the FPGA, and the control module controls the time delay of each channel after dividing the frequency of the clock.

Further, the GNSS system interface and the display module are also included,

the GNSS system interface is used for connecting the upper computer with the GNSS system, receiving the position information and positioning the initial position;

the display module is used for displaying the received position information on a GIS map; after the upper computer sends data, the generated airplane information and flight track are displayed on the GIS map control synchronously, and important airplane parameter data are displayed in real time by using the accompanying flight sign.

The invention has the following beneficial effects:

the invention can simulate multi-channel transmission scenes of ADS-B signals to generate ADS-B interweaving signals, ADS-B message signals output by each channel can be flexibly set, each channel can output more than 6000 ADS-B messages in a single channel within 1 second, and each channel can also carry out simulated flight according to flight track patterns preset by upper computer software, so that the signals received by a receiver form patterns with certain shapes on a monitoring interface.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.

FIG. 1 is a flow chart of an ADS-B multichannel signal generation method in an embodiment of the present invention;

FIG. 2 is a diagram illustrating a format of a composite frame for transmission according to an embodiment of the present invention;

fig. 3 is a schematic connection diagram of the components of the ADS-B multi-channel signal generation method in the embodiment of the present invention.

Detailed Description

The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the embodiments of the invention serve to explain the principles of the invention.

The embodiment of the invention discloses an ADS-B multichannel signal generation method, which comprises the following steps as shown in figure 1:

s101, an upper computer acquires multi-channel message data and determines an ADS-B message output scheme;

wherein, the step S101 specifically comprises the steps of,

1) obtaining multi-path message data

Specifically, the multiple paths of messages correspond to multiple message channels, and the message data information of each channel includes:

a channel number of the message;

relative time delay of the channels; the relative time delay is the relative time delay between different channels, for example, the time delay of the channel relative to the first channel;

the number of targets contained within a channel; the target is an aircraft;

the working parameter data of each target in the channel comprises:

selecting a working mode of the airplane, setting a secondary code, setting an identification code and setting an S-mode address;

setting the maximum flight speed of the airplane, setting the airplane category, setting the type of an air-ground switch, setting the length and the width of the airplane, setting a special mode identification code and setting the type of an ADS-B message;

the initial position (longitude and latitude) of the airplane, the height of the airplane and the number of messages generated per second;

and (4) a scheme of a flight path graph of the airplane.

Wherein, the flight path pattern of the airplane contained in the parameter information can be a straight line path, a spiral path, a circular path and other special pattern paths,

optionally, the message data information may be input with parameter information through a human-computer interaction interface set on the upper computer;

and the track pattern can also be stored in an external file, and the upper computer directly reads track data in the external file to combine into a message to simulate the flight track through a command or a man-machine interaction mode.

2) Setting a message output scheme according to the acquired message data;

the message output scheme refers to the formulation of information such as the output flight trajectory of each channel, airplane parameter information, the output delay of each channel relative to the first channel and the like, and message channels are distributed according to the batch, the number of frames, the airspace and other related contents of airplanes in the obtained message data content to form the message content of each channel to form the output message scheme.

Optionally, the specific message generation scheme may also be flexibly set according to the purpose of the test in the process of using by the user, for example, the position, altitude, speed, and the like of the airplane flying are set by the user according to the test purpose.

3) Respectively encoding the message data of each channel according to the data type;

coding the input data item information according to the ADS-B standard to form a message frame data format, such as information of calculating longitude and latitude codes, altitude codes, speed codes, airplane ID and the like;

and storing the information into a temporary file, and generating ADS-B message data after coding of each channel according to the output message scheme of each channel and the parameter information.

Step S102, generating a multi-channel transmission composite frame according to the output scheme of the message and sending the multi-channel transmission composite frame to a terminal;

specifically, the transport composite frame format, as shown in fig. 2, includes a synchronization header, a channel enable field (1-N), a delay field (1-N), a frame data section (1-N), and a CRC;

a sync header, which is 2 bytes and can be set to 0x7e,0x7 e;

a lane enable field (1-N) for determining N according to the number of lanes in the output scheme; each channel is enabled to be 1BIT,0 represents channel prohibition, and 1 represents channel enable output;

the delay field (1-N) represents the delay time of each output channel, the length of the delay field of each channel is one byte, and each channel can be set to delay 255 clock cycles to the maximum extent;

frame data segments (1-N), wherein each frame data field is ADS-B message data after each channel is coded, parameter information of each channel is set, each parameter information is set according to the test purpose of a user, the information is coded according to the standard of ADS-B, each data item information is coded to form an ADS-B message frame of each channel, and the ADS-B message frame is refilled to a fixed byte position in the corresponding frame data segment in the transmission composite frame.

Specifically, the time length of the delay can also be set by the terminal.

Step S103, the terminal receives the multi-channel transmission composite frame data, and forms a multi-channel radio frequency signal to be sent through an antenna after the data analysis and modulation are carried out on the composite frame;

wherein, the step S103 specifically comprises the steps of,

1) after receiving frame data stream, detecting a synchronous frame header, and after finding the synchronous frame header, carrying out data verification on a transmission frame;

2) after the data is checked to be correct, the CRC of ADS-B message data flow of each channel is checked and analyzed;

3) respectively extracting frame data, an enable bit and a delay size of each channel, and generating ADS-B baseband signals of each channel after PPM modulation and accurate delay control;

the specific precise time delay control is that a constant temperature crystal oscillator is adopted on a terminal machine to provide a source clock for a PLL management chip; the PLL management chip outputs a stable clock to the FPGA of the terminal; the FPGA controls the time delay of each channel through frequency division; specifically, the clock control period for controlling message output is 20 nanoseconds, and the error of the output control clock is ensured not to exceed 1 nanosecond.

Specially, in the embodiment of the invention, the multi-path and interweaving characteristics among ADS-B multi-channel signal channels can be simulated through the delay control of each channel; the channel delay can be regarded as multi-channel delay of signals, and the output speed of the message is obviously improved due to the adoption of multiple channels and the FPGA for message output.

4) And modulating the ADS-B baseband model of each channel to 1090MHz carrier waves, amplifying and transmitting by an antenna.

Preferably, the method further comprises a map display method, wherein the upper computer is connected with the GNSS system to obtain GNSS information, performs initial position positioning on the position information contained in the obtained multi-path message data, and displays the position information on the GIS map; after the upper computer sends data, the generated airplane information and flight track are synchronously displayed on the GIS map control, and important airplane parameter data are displayed in real time in a tag mode accompanied with flight.

The important airplane parameters include airplane number, position (longitude and latitude), airplane height, speed and the like.

The ADS-B multichannel signal generated by the embodiment of the invention conforms to the ADS-B standard, on one hand, the ADS-B multichannel signal can be used for simulating the ADS-B signal in the air to verify the performance, the system function and the like of the ADS-B receiver; on the other hand, in the aspect of fighting against the foreign ADS-B system, the foreign ADS-B system can be interfered and deceived.

The embodiment of the invention also discloses an ADS-B multichannel signal generation method, as shown in figure 3, comprising an upper computer and a terminal; the upper computer is connected with the terminal through an RS232 interface;

the upper computer is internally provided with a message data acquisition module, a message output scheme generation module, a message data coding module, a multi-channel transmission synthetic frame generation module and a serial port module;

the message data acquisition module acquires message data including output types of a plurality of channel messages, the number of generated target airplanes, a working mode, secondary code setting, flight identification code setting, S mode address setting, maximum flight speed, initial longitude and latitude of the airplane and the like;

the message output scheme generation module is used for setting a message output scheme according to the acquired message data;

the multi-channel transmission synthesis frame generation module is used for synthesizing multi-channel transmission synthesis frame data according to a set message output scheme and the coded message data; the specific composite frame structure is shown in fig. 2.

Specifically, the serial port module is an RS232 serial port.

The terminal comprises an interface module, an FPGA, a state monitoring module, a multi-channel radio frequency output module, an antenna and a power supply module;

the interface module is connected with a serial port module of the upper computer, receives serial data sent by the upper computer through the serial data and then sends the serial data to the FPGA module;

specifically, the FPGA module adopts a constant temperature crystal oscillator with high precision to provide a source clock for a clock management module (PLL management chip), the PLL management chip outputs a required stable clock to a control module in the FPGA, the control module performs accurate delay control on each channel after frequency division is performed on the clock, the clock control period of message output is controlled to be 20 nanoseconds, and the error of the output control clock is ensured not to exceed 1 nanosecond.

The multi-channel radio frequency output module modulates the N channels of PPM modulated multi-channel data output by the FPGA module onto 1090MHz carrier waves and then amplifies the carrier waves;

the antenna is connected with the multi-channel radio frequency output module and sends out the multi-channel data after radio frequency amplification.

The state monitoring module is mainly used for monitoring the running states of hardware equipment and software, and comprises information such as running current, power consumption, message sending rate, message sending progress, message sending frame number and the like.

The power supply module mainly performs power supply conversion and power supply for the FPGA and the hardware functional module.

Preferably, the ADS-B multichannel signal generating method of this embodiment further includes a GNSS system interface and a display module,

the GNSS system interface is used for connecting the upper computer with the GNSS system and receiving the position information to carry out initial position positioning;

the display module is used for displaying the received position information on a GIS map; after the upper computer sends data, the generated airplane information and flight track are synchronously displayed on the GIS map control, and important airplane parameter data are displayed in real time in the form of a flying tag.

In summary, the ADS-B multichannel signal generating method according to the embodiment of the present invention can simulate a multi-channel transmission scene of the ADS-B signal to generate an ADS-B interleaved signal, and the ADS-B message signal output by each channel can be flexibly set, and each channel can output more than 6000 ADS-B messages in a single channel within 1 second, and each channel can also simulate flight according to a flight trajectory pattern preset by upper computer software, so that a signal received by a receiver forms a pattern with a certain shape on a monitoring interface.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims

1. An ADS-B multichannel signal generation method is characterized by comprising the following steps:

the multichannel transmission composite frame comprises a synchronous head, a channel enabling field, a delay field, a frame data section and CRC;

the synchronization header comprises 2 bytes;

the CRC is a cyclic redundancy check code which is a check code of the whole transmission frame;

the terminal receives the multi-channel transmission composite frame data, and forms a multi-channel radio frequency signal to be transmitted through an antenna after data analysis, modulation, amplification and multi-channel delay control;

the processing procedure of the terminal comprises the following steps:

the specific precise time delay control is that a constant temperature crystal oscillator is adopted on a terminal machine to provide a source clock for a PLL management chip; the PLL management chip outputs a stable clock to the FPGA of the terminal; the FPGA controls the time delay of each channel through frequency division; the clock control period for controlling message output is 20 nanoseconds, and the error of the output control clock is ensured not to exceed 1 nanosecond;

through the delay control of each channel, the method is used for simulating the multipath and interweaving characteristics among ADS-B multi-channel signal channels; the channel delay is the multipath delay of the signal;

2. The multi-channel signal generation method of claim 1, further comprising a map display method, the method comprising:

3. An ADS-B multichannel signal generation method is characterized by comprising an upper computer and a terminal; the upper computer is connected with the terminal through a serial interface;

the terminal is used for receiving the multi-channel transmission composite frame data, and forming a plurality of paths of radio frequency signals to be transmitted through the antenna after carrying out data analysis, modulation, amplification and multi-channel delay control on the composite frame;

the serial port module converts the multi-channel transmission composite frame into a serial data format and sends the serial data format to the terminal through a serial port;

the terminal comprises an interface module, an FPGA module, a multi-path radio frequency output module, an antenna and a state monitoring module;

the state monitoring module is used for monitoring information including the operating current and power consumption of the terminal machine, the sending rate, the sending progress and the message sending frame number of the message;

the FPGA module adopts a constant-temperature crystal oscillator to provide a source clock for the PLL management chip, the PLL management chip outputs the clock to the control module in the FPGA, and the control module controls the time delay of each channel after dividing the frequency of the clock; the clock control period of the control message output is 20 nanoseconds, and the output control clock error is ensured not to exceed 1 nanosecond.

4. The multi-channel signal generation method of claim 3, further comprising a GNSS system interface and a display module,