High-speed data transmission method for secondary radar and collision avoidance systemTechnical Field
The invention relates to the technical field of data processing and transmission, in particular to a high-speed data transmission method of a secondary radar and anti-collision system.
Background
The secondary radar realizes the detection and monitoring of the aircraft through an inquiry response mechanism, and comprises the steps of acquiring parameters such as an identity code and a flight height of a target, and realizing the coverage of an airspace in a working distance through scanning of an antenna beam. The query/receiving beams formed by the mechanical scanning radar are all analog synthesis, and the active phased array radar realizes the synthesis of the query/receiving beams through a digital beam forming technology. Mechanically scanning the radar to form an inquiry/receiving beam with a fixed azimuth, and driving the antenna to rotate by the turntable to realize the change of beam pointing; the normal fixed direction of the active phased array radar antenna is unchanged, and the change of beam direction is realized by controlling the current phase of each channel, so that the secondary radar equipment needs to control the characteristics of the radiated signals of each antenna channel, and the active phased array radar antenna is more complex and flexible than a mechanical scanning radar. Currently, digital beam forming works in accordance with an inherent design within signal processing equipment, both in a mechanically scanned system and in an active phased array system.
At the beginning of the 90 s of the 20 th century, the chief science of the U.S. MITRE company and j. The software radio provides a brand-new idea of designing, developing and using a radio communication system and equipment, gets rid of the traditional radio design idea of completely relying on hardware for application, separates the service provided by the system from the mode of a fixed circuit on a modularized general hardware platform, and improves the wireless communication development technology to a new height by utilizing the advantages of software programmability, easy modification, easy maintenance, low cost (less hardware investment) and the like.
The secondary radar system is especially a secondary radar system adopting an active phased array scanning system, and can be designed in a generalized and modularized way based on a software radio idea.
At present, the decoding of the response signals of most secondary radars and anti-collision systems is directly completed by signal processing equipment, the data transmitted to display control equipment is point track data processed by embedded software, the participation degree of back-end software is low, and the processing flexibility is extremely low.
All TR channels of the phased array secondary radar are digitally controllable in amplitude and phase, so that the control of the receiving and transmitting beam direction and shape is realized. At present, the beam forming, decoding, trace point aggregation, track processing and the like of the secondary radar systems of most phased array systems are completed by FPGA+PowerPC, so that the secondary radar systems are rapid and efficient, but have the defects of lower flexibility, and if the algorithm improves the performance to be improved, the program solidified by each processing unit in the equipment is required to be updated respectively, so that the maintainability is poor; meanwhile, as the data received and transmitted by all channels can influence the performance of the system, compared with ground equipment, the maintenance of the airborne equipment is poorer, and the storage requirement on the original data is more outstanding for facilitating the later analysis.
Therefore, there are many urgent improvements in the data transmission of the existing phased array secondary radar system and the anti-collision system, especially in the data transmission rate, and optimization and improvement are needed to achieve a higher data transmission rate, so as to improve the operation efficiency and reliability of the overall system.
Disclosure of Invention
In order to solve the defects of the prior art mentioned in the above description, the invention provides a high-speed data transmission system and a high-speed data transmission method of a secondary radar and anti-collision system, which provide an effective solution for the secondary radar system and the anti-collision device to transmit the received data closer to an antenna to a rear-end data processing device, and improve the efficiency and the reliability of data transmission, thereby improving the operation efficiency and the reliability of the whole system.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a high-speed data transmission system for a secondary radar and collision avoidance system, comprising:
the signal processing module comprises a signal acquisition unit for receiving baseband data and a packaging unit for packaging the baseband data;
the data transmission module comprises an interface unit for connecting the packaging unit and a photoelectric conversion unit for carrying out data transmission conversion, and the photoelectric conversion unit is connected with an optical fiber;
the data processing module comprises a network interface unit for receiving optical fiber transmission data, a time sequence recovery unit for demodulating the data and a data processing unit for analyzing and processing the data.
The high-speed data transmission system of the secondary radar and the anti-collision system disclosed by the above is used for collecting and processing data signals through the signal processing module, packaging the signal data after obtaining the signal data, and transmitting the signal data to the back-end processing equipment at high speed through the transmission link, wherein the back-end processing equipment can recover time sequence to obtain the initial data again, and the back-end equipment can realize the speed improvement through high-performance equipment and the like when reading the data. Therefore, on the premise of not improving the performances of the front-end data acquisition equipment and the transmission equipment, more efficient processing of the data is realized, the data is processed and transmitted at a high speed in the process, and the transmission efficiency is improved.
Further, in the system, the signal obtained by the signal acquisition module is an electrical signal, and in the transmission process, the signal is an optical signal, and the process is realized through the photoelectric conversion unit, and specifically, the invention optimizes and selects one of the following possible choices: the photoelectric conversion unit comprises a single-mode optical module. By adopting the scheme, the single-mode optical module can provide reliable guarantee in long-distance and high-speed transmission.
Furthermore, in the system, data transmission is performed through an ethernet network, and specifically, the interface unit includes an FPGA for implementing protocols of each layer of the ethernet network.
The invention also discloses a corresponding high-speed data transmission method of the secondary radar and the anti-collision system, which comprises the following steps:
a high-speed data transmission method of a secondary radar and anti-collision system is applied to the data transmission system and is used for transmitting and processing signal data sent in a certain time slot, and the method comprises the following steps:
splitting continuous baseband data in a time slot into a plurality of fragments, and filling each fragment into a communication message to form a frame;
transmitting the communication message to a receiver through a tera Ethernet;
the receiver receives the communication message and extracts all fragments from the message, and the fragments in the same time slot are combined and spliced to recover the complete baseband data in the time slot;
and carrying out subsequent processing on the recovered baseband data.
Furthermore, in the method, the UDP protocol is adopted as an Ethernet transmission layer protocol, and when the baseband data is split, continuous baseband data is split according to the number of sampling points which can be transmitted by the UDP protocol, so that the split fragments form a frame data signal.
Furthermore, a certain time interval exists between two adjacent time slots, when the baseband data is split, the baseband data in different time slots are split, then are randomly limited and combined and filled into the communication message, and when the data is recovered, only the fragments split in the same time slot are combined to recover the initial baseband data.
Still further, to facilitate data recovery, it is necessary to identify the time slots of the signal data, where optimization is performed and one of the possible choices is given: each slot is marked to form a unique slot ID that is distinct from the other slots.
Still further, in order to facilitate accurate regression of each segment into the corresponding time slot and combination in the correct order, the optimization setup is set forth herein and one of the possible schemes is given as follows: when the baseband data in each time slot is split into a plurality of fragments, each fragment in the time slot is marked with a time slot ID and an internal sequence number is marked.
Furthermore, the baseband data is sent out by the communication message in a splitting and recombining mode, and the sampled baseband data can be formed into a complete communication message after a certain time is accumulated, so that the following feasible scheme is optimized and listed here: and setting a buffer memory in the FPGA, temporarily storing fragments obtained by splitting the baseband data in the buffer memory, and transmitting the message to a receiver after the fragments in the buffer memory are combined to reach a complete communication message. By adopting the scheme, the baseband signal fragments acquired at high speed can be temporarily stored, and the baseband signals can be continuously acquired conveniently; and can quickly compose a message to send out, thereby avoiding transmission blocking or transmission interruption caused by network delay or signal acquisition interruption and other problems.
Still further, the writing of the buffer is realized by the signal processing module, the speed is limited, and the reading of the buffer is realized by the tera ethernet, so that the reading rate is far greater than the writing rate, and the buffer depth is greater than the number of sampling points of a single communication message.
Compared with the prior art, the invention has the following beneficial effects:
in the invention, the baseband data is sampled and packaged, then is transmitted at high speed, and the receiving party carries out data processing after time sequence recovery; a large amount of data information at the front end can be quickly transmitted to the data processing equipment at the rear end, and high-efficiency processing is performed through high-performance equipment; and further, the problems of low efficiency and high cost existing in the process of transmitting the data after the data processing module is arranged at the front end are avoided.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a block diagram of a secondary radar system to which the data transmission system of the present invention is applied.
Fig. 2 is a block diagram of a high-speed data transmission system of the secondary radar and collision avoidance system.
Fig. 3 is a block diagram of the FPGA teraudp transport logic design.
Fig. 4 is a time axis of the alternation of interrogation slots and reply slots of the secondary radar.
Fig. 5 is a schematic diagram of a data encapsulation process flow.
Fig. 6 is a schematic diagram of an ethernet data frame structure.
Fig. 7 is a schematic diagram of processing steps of a method for high-speed data transmission of a secondary radar and collision avoidance system.
Detailed Description
The invention is further illustrated by the following description of specific embodiments in conjunction with the accompanying drawings.
It should be noted that the description of these examples is for aiding in understanding the present invention, but is not intended to limit the present invention. Specific structural and functional details disclosed herein are merely representative of example embodiments of the invention. This invention may, however, be embodied in many alternate forms and should not be construed as limited to the embodiments set forth herein.
Example 1
Aiming at the problem of limited rate of data transmission of the existing secondary radar system, the embodiment performs optimization and improvement to solve the problem in the prior art.
As shown in fig. 2, a high-speed data transmission system of a secondary radar and collision avoidance system includes:
the signal processing module comprises a signal acquisition unit for receiving baseband data and a packaging unit for packaging the baseband data;
the data transmission module comprises an interface unit for connecting the packaging unit and a photoelectric conversion unit for carrying out data transmission conversion, and the photoelectric conversion unit is connected with an optical fiber;
preferably, the interface unit in this embodiment adopts a high-speed transmission interface.
The FPGA Mo Zhaowang interface adopts an Xilinx 10G Ethernet PCS/PMA core and a 10GEthernet MAC core to realize an Ethernet link layer, and a network layer (IP) and a transport layer protocol (UDP) are directly realized by using hardware description languages.
The data processing module comprises a network interface unit for receiving optical fiber transmission data, a time sequence recovery unit for demodulating the data and a data processing unit for analyzing and processing the data.
The high-speed data transmission system of the secondary radar and the anti-collision system disclosed by the above is used for collecting and processing data signals through the signal processing module, packaging the signal data after obtaining the signal data, and transmitting the signal data to the back-end processing equipment at high speed through the transmission link, wherein the back-end processing equipment can recover time sequence to obtain the initial data again, and the back-end equipment can realize the speed improvement through high-performance equipment and the like when reading the data. Therefore, on the premise of not improving the performances of the front-end data acquisition equipment and the transmission equipment, more efficient processing of the data is realized, the data is processed and transmitted at a high speed in the process, and the transmission efficiency is improved.
In the system, the signal obtained by the signal acquisition module is an electrical signal, and in the transmission process, the signal is an optical signal, and the process is realized through the photoelectric conversion unit, specifically, in the embodiment, the following feasible selection is adopted and optimized: the photoelectric conversion unit comprises a single-mode optical module. By adopting the scheme, the single-mode optical module can provide reliable guarantee in long-distance and high-speed transmission.
In the system, data transmission is performed through an ethernet network, and specifically, the interface unit includes an FPGA for implementing protocols of each layer of the ethernet network.
As shown in fig. 1, the secondary radar signal processing device adopts an fpga+a single-mode optical module to realize a tera ethernet interface, and the single-mode optical module realizes photoelectric signal conversion; the Ethernet protocols are realized by FPGA, the tera-mega network line speed is 10.3125Gbps, and the FPGA needs to select the high-speed serial interface to support the speed level of 10.3125 Gb.
The FPGA Mo Zhaowang interface adopts an Xilinx 10G Ethernet PCS/PMA core and a 10GEthernet MAC core to realize an Ethernet link layer, and a network layer (IP) and a transport layer protocol (UDP) are directly realized by using hardware description languages.
Example 2
The content of the above embodiment describes a high-speed data transmission system of a secondary radar and an anti-collision system, and the embodiment also discloses a corresponding high-speed data transmission method of the secondary radar and the anti-collision system, which comprises the following specific steps:
as shown in fig. 3 to 7, a high-speed data transmission method for a secondary radar and collision avoidance system, which is applied to the data transmission system and is used for transmitting and processing signal data transmitted in a certain time slot, includes:
s1, splitting continuous baseband data in a time slot into a plurality of fragments, and filling each fragment into a communication message to form a frame;
s2, transmitting the communication message to a receiver through a tera Ethernet;
s3, receiving the communication message by the receiver, extracting all fragments from the message, and combining and splicing the fragments in the same time slot to recover the complete baseband data in the time slot;
s4, carrying out subsequent processing on the recovered baseband data.
In the method, a UDP protocol is adopted as an Ethernet transmission layer protocol, and when baseband data is split, continuous baseband data is split according to the number of sampling points which can be transmitted by the UDP protocol, so that split fragments form a frame data signal. The UDP protocol provides connectionless transmission, no connection is required to be established before communication, data is allowed to be accidentally lost and retransmission is avoided, so that even if a packet loss phenomenon occurs in a communication link, data blockage is avoided, and the UDP protocol is suitable for real-time continuous data transmission.
When the baseband data is split, the baseband data in different time slots are split, then are randomly limited and combined and filled into a communication message, and when the data is recovered, only fragments split in the same time slot are combined to recover the initial baseband data.
Preferably, the secondary radar monitors the aircraft by adopting an inquiry response mechanism, inquiry and response are carried out in a time-sharing manner, and a time axis consists of alternate inquiry time slots and response time slots; the data signal in the response time slot of the secondary radar signal therefore belongs to the object to be acquired. Similarly, in the application of the collision avoidance system, the signal time sequence is the same as the secondary radar time sequence, so that the method disclosed in the embodiment can also be adopted to realize the high-speed data transmission of the collision avoidance system.
To facilitate data recovery, the time slots of the signal data need to be identified, here optimized and one of the possible choices employed: each slot is marked to form a unique slot ID that is distinct from the other slots.
In order to facilitate accurate regression of each segment into the corresponding time slot and combination in the correct order, the optimization is set here and one of the possible schemes is adopted: when the baseband data in each time slot is split into a plurality of fragments, each fragment in the time slot is marked with a time slot ID and an internal sequence number is marked.
The baseband data is sent out by the communication message in a split and recombination mode, and the sampled baseband data can form a complete communication message after a certain time accumulation, so that the method is optimized and adopts the following feasible scheme: as shown in fig. 5, a buffer is set in the FPGA, fragments obtained by splitting baseband data are temporarily stored in the buffer, and after the fragments in the buffer are packaged to reach a complete communication message, the message is transmitted to a receiving party. By adopting the scheme, the baseband signal fragments acquired at high speed can be temporarily stored, and the baseband signals can be continuously acquired conveniently; and can quickly compose a message to send out, thereby avoiding transmission blocking or transmission interruption caused by network delay or signal acquisition interruption and other problems.
Preferably, because of the UDP protocol adopted in the present embodiment, the communication packet is a UDP packet, and in order to facilitate accurate decoding of the back-end data processing, information such as a corresponding interrogation mode and an interrogation beam direction of the secondary radar in the current interrogation response time slot is also required to be filled in the UDP frame.
Preferably, as shown in fig. 3, the writing of the buffer memory is realized by a signal processing module, the speed is limited, and the reading of the buffer memory is realized by a tera ethernet, so that the reading rate is far greater than the writing rate, and therefore, the buffer memory depth is greater than the sampling point number of a single communication message.
In this embodiment, when the above method is used for data processing, the writing rate of the buffered data is fs, and the buffered data is read as the terabyte transmission logic interface clock fr, and since the reading rate fr is far greater than the writing rate fs, the buffering depth must be greater than the number of sampling points of a single UDP packet.
The length of the response time slot is closely related to the action distance of the secondary radar, and the action distance of the secondary radar is set asR (units: km), then the total number of sampling points in one acknowledgement slot ns The method comprises the following steps:wherein c is the speed of light (unit: m/s).
From the foregoing, the data of one sampling point is:bytes, if each UDP message length is L (bytes), then one message can transmit the sampling point number NL The method comprises the following steps: />Byte, UDP frame number n required for transmitting data in one response time slotf The method comprises the following steps: />
In this embodiment, a data server is used to process data, the data processing server processes the received data in a back-end manner by taking a response time slot as a unit, extracts baseband data in a discrete message transmitted by a tera-meganetwork and completes time sequence recovery, and detects the start and end points of the response time slot, so that a frame sequence number field in the response time slot is added in a UDP frame to perform identification to realize the function; at the same time, each response time slot should also be provided with a separate time slot ID number (0-nf -1); the back-end data processing is to decode accurately, and the information such as the corresponding inquiry mode, inquiry beam direction and the like of the secondary radar in the current inquiry response time slot is also required to be filled in the UDP frame.
The above is an embodiment exemplified in this example, but this example is not limited to the above-described alternative embodiments, and a person skilled in the art may obtain various other embodiments by any combination of the above-described embodiments, and any person may obtain various other embodiments in the light of this example. The above detailed description should not be construed as limiting the scope of the present embodiments, which is defined in the claims and the description may be used to interpret the claims.