CN102981162A - Spatial synchronization device and synchronization method for bistatic SAR - Google Patents

Abstract

The invention discloses a spatial synchronization device and a synchronization method for bistatic SAR (synthetic aperture radar). The device comprises a transmission station part and a receiving station part, and particularly comprises a positioning and attitude determination system, an antenna server, a transmission synchronization system, a wireless transmit-receive system, a receiving synchronization system and a display unit. According to the spatial synchronization device and the method, direction angles at which antenna beams of transmit-receive aerial carrier platforms aim at an target area are revolved and obtained by utilizing actual spatial positions of the transmit-receive aerial carrier platforms; the antenna server is utilized to accomplish aiming of the beams to allow the antenna beams of the transmit-receive platforms to aim at the target area; the spatial synchronization of the onboard bistatic SAR is achieved; a signal-to-noise ratio of a radar echo is ensured; and the precision of the spatial synchronization is improved.

Description

Spatial Synchronization Device and Synchronization Method for Bistatic SAR

technical field

The invention belongs to the technical field of radar signal processing, and relates to GPS positioning technology, in particular to airborne bistatic synthetic aperture radar (Synthetic Aperture Radar, SAR) space synchronization technology.

Background technique

Bistatic SAR is a synthetic aperture radar with a new system of receiving and transmitting separately. It has different spatial geometric coordinate relations, anti-jamming performance, concealment, and strong anti-intercept ability. Bistatic SAR includes space-borne bistatic SAR for satellite launch and satellite reception, satellite bistatic SAR for satellite launch and aircraft reception, and airborne bistatic SAR for aircraft launch and aircraft reception.

The schematic diagram of the spatial structure of the airborne bistatic SAR is shown in Figure 1. Due to the separation of the transceivers, the airborne bistatic SAR has a new spatial geometry, which brings about the spatial synchronization problem of the airborne bistatic SAR. Space synchronization requires that the antenna beams of the transmitting station and the receiving station have overlapping irradiation areas on the same target area, so as to ensure that the echo in the imaging area has a sufficient sex-to-noise ratio, which is the guarantee for synthetic aperture radar imaging. Due to the separate location of the transceiver and the movement of the transceiver and the carrier, the space position is constantly changing, so it is more difficult to realize the space synchronization of the airborne bistatic SAR.

Literature: Research on Synchronization of Bistatic Synthetic Aperture Radar System, Tang Ziyue; Zhang Shourong, Modern Radar, Vol.26, No.1, pp.1-2, 2004, proposed a solution to the space synchronization problem of airborne bistatic SAR The method is specifically as follows: before the transceiver carrier aircraft performs imaging work, calculate the antenna beam pointing angle of the transceiver carrier aircraft in advance according to the predetermined flight path of the transceiver carrier aircraft and the position of the imaging area, and adjust the antenna beam of the transceiver carrier aircraft before the test Pointing angle, through the control of the speed, heading and attitude of the transceiver aircraft during flight, the antenna beams of the transceiver aircraft are all aimed at the imaging area. The disadvantage of this method is that the antenna beam pointing angle cannot be automatically controlled by the system according to the actual spatial position of the aircraft, and the alignment accuracy of the transmitting and receiving antenna beams is greatly affected by the difference between the actual flight path and the predetermined flight path of the aircraft.

Contents of the invention

The object of the present invention is to solve the above-mentioned problems existing in the prior art, and propose a space synchronization device for bistatic SAR, and a synchronization method for bistatic SAR based on the device.

In order to describe content of the present invention conveniently, at first do following term definition:

Definition 1. Synchronization system

In the present invention, the synchronization system is divided into a transmission synchronization system and a reception synchronization system, which are used in the transmission station and the reception station respectively. It can be realized with the help of FPGA technology, and it is a hardware system that plays a core control role in the space synchronization device.

Definition 2. Serial port

Serial port is the abbreviation of serial communication interface. Its data transmission method is transmitted one by one in sequence. The serial communication interface is divided into RS-232, RS-422, RS485, etc. according to electrical standards and protocols.

Definition 3. Positioning and attitude measurement system

The positioning and attitude measurement system refers to a system that can provide real-time attitude data (yaw angle, pitch angle, and roll angle) and spatial position (longitude, latitude, and altitude) information of the carrier.

Definition 4, cyclic redundancy check

Cyclical Redundancy Check, or CRC for short, uses the principle of division and remainder to detect errors. In practical applications, the sending device calculates the CRC value and sends it to the receiving device together with the data. The received data recalculates the CRC and compares it with the received CRC. If the two CRC values are different, it means that there is an error in the data communication.

Definition 5. Antenna server

The antenna server (hereinafter referred to as "server") is composed of a data calculation module, a servo motor and a turntable. The data calculation module receives and calculates the control data and attitude data of the synchronization system through the serial port, and forms the control information of the server in real time; The servo motor uses the above control information to control the turntable to rotate to the specified direction, and uses the above attitude data to stabilize the antenna pointing; the antenna is placed on the turntable; at the same time, the server will transmit the actual pointing of the antenna turntable back to the synchronization system through the serial port in real time.

Definition 6. Wireless transceiver system

A wireless transceiver system refers to a system that can realize long-distance wireless data transmission.

Definition 7. Display and control unit

The display and control unit refers to the application software that communicates with the synchronization system of the receiving station through the serial port, can display the flight status of the transceiver carrier aircraft and the direction of the antenna beam of the transceiver carrier aircraft, and plays a monitoring role in space synchronization. The display and control unit is installed on the display terminal (host, etc.), and the display and control unit may specifically be display and control software.

Definition 8. Antenna beam pointing angle

The antenna beam pointing angle refers to the azimuth and elevation angles of the centerline of the antenna beam. The azimuth angle refers to the horizontal angle between the north pointing line of the carrier platform and the centerline of the antenna beam in a clockwise direction; the pitch angle refers to the angle between the horizontal plane of the carrier platform and the centerline of the antenna beam.

A space synchronization device for bistatic SAR provided by the present invention includes a transmitting station part and a receiving station part, wherein the transmitting station end specifically includes: a first positioning and attitude measurement system, a first antenna server, a transmitting synchronization system and The first wireless transceiver system; the receiving station end specifically includes: a second positioning and attitude measurement system, a second antenna server, a receiving synchronization system, a second wireless transceiver system and a display unit;

The first positioning and attitude measuring system is used to obtain the attitude data information and spatial position information of the carrier aircraft, and transmit the obtained information to the launch synchronization system;

The transmitting synchronization system calculates the pointing angle when the antenna beam of the transmitting station is aimed at the target area according to the spatial position obtained by the first positioning and attitude measurement system and the known spatial position of the target area, and combines the calculated pointing angle and the carrier The attitude angle of the aircraft is sent to the first antenna server;

The first antenna server controls the antenna of the transmitting station to adjust the antenna pointing according to the received pointing angle when the antenna beam of the transmitting station is aligned with the target area, and transmits the current actual pointing angle of the antenna to the transmitting synchronization system;

The second positioning and attitude measurement system is used to acquire the spatial position and the known spatial position of the target area, and transmit the acquired position information to the receiving synchronization system;

The first wireless transceiver system is used to send the spatial position information, attitude information and actual pointing angle of the transmitting station to the second wireless transceiver system;

The second wireless transceiver system is used to receive the sending space position information, attitude information and actual pointing angle of the transmitting station, and transmit it to the receiving synchronization system;

The receiving synchronization system calculates the pointing angle when the antenna beam of the receiving station is aimed at the target area according to the spatial position obtained by the second positioning and attitude measurement system and the known spatial position of the target area, and combines the calculated pointing angle and The attitude angle of the carrier aircraft is sent to the antenna server of the receiving station;

The second antenna server receives the pointing angle of the antenna beam of the receiving station transmitting station when it is aligned with the target area, controls the antenna of the receiving station to adjust the antenna pointing, and transmits the current actual pointing angle of the antenna to the receiving synchronization system;

The receiving synchronization system is also used to transmit the spatial position information, attitude information and current actual directional angle of the antenna of the transmitting station and the spatial position information, attitude information and current actual directional angle of the antenna to the display unit;

The display unit is used to display the spatial position information, attitude information and current actual directional angle of the antenna of the transmitting station and the spatial position information, attitude information and current actual directional angle of the antenna of the receiving station.

Further, the spatial position information of the carrier aircraft includes: longitude, latitude, and altitude of the spatial position, and the attitude data information is specifically the attitude angle of the carrier aircraft, including: yaw angle, pitch angle, and roll angle.

Further, the specific calculation process of the pointing angle when the antenna beam is aimed at the target area is as follows:

Introduce intermediate variables X, Y, N in the solution process, where

$\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span>$

$\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span>$

$\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span>$

The azimuth β is:

βX-Y

The pitch angle θ is:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Hm</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; HR</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; min</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; Hm</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; HR</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; .</span>$

Among them, Lor represents the longitude of the spatial position of the carrier aircraft, Lar represents the latitude of the spatial position of the carrier aircraft, Hr represents the altitude of the spatial position of the carrier aircraft, Lom represents the longitude of the spatial position of the target area, and Lam represents the spatial position of the target area The latitude of , Hm represents the altitude of the spatial position of the target area, and R represents the radius of the earth.

In order to solve the above problems, the present invention also proposes a space synchronization method for bistatic SAR, comprising the following steps:

Step 1: Obtain the spatial position information and attitude data information of the carrier aircraft,

The first positioning and attitude measuring system at the transmitting station and the second positioning and attitude measuring system at the receiving station obtain the spatial position information and attitude data information of the carrier aircraft, and respectively convert the acquired spatial position information and attitude data information of the carrier aircraft to The transmission synchronization system transmitted to the transmitting station and the reception synchronization system at the receiving end;

Step 2: Calculate the antenna beam pointing angle,

The transmission synchronization system of the transmitting station calculates the antenna beam pointing angle of the antenna beam of the transmitting station to the target area according to the obtained spatial position information of the terminal carrier of the transmitting station and the known spatial position information of the target area; The synchronization system calculates the antenna beam pointing angle of the antenna beam of the receiving station to the target area according to the obtained spatial position information of the receiving station terminal carrier and the known spatial position information of the target area;

Step 3: Send the antenna beam pointing angle calculated in step 2 to the server, and the server controls the antenna to adjust the pointing,

The transmitting synchronization system and the receiving synchronization system respectively calculate the antenna beam pointing angle of the transmitting station's antenna beam at the target area, the attitude angle of the carrier aircraft, and the antenna beam pointing angle of the receiving station's antenna beam at the target area, the carrier aircraft's The attitude angle is sent to the first antenna server of the transmitting station and the second antenna server of the receiving station, and the first antenna server and the second antenna server respectively control the antenna of the transmitting station to adjust the antenna pointing according to the received antenna beam pointing angle and the receiving station antenna to adjust the antenna pointing, the server will stabilize the antenna pointing according to the attitude angle of the carrier aircraft, and transmit the current actual pointing angle of the antenna to the transmitting synchronization system and the receiving synchronization system respectively;

Step 4: Data display,

The first wireless transceiver system of the transmitting station sends the spatial position information, attitude information and actual pointing angle of the transmitting station to the second wireless transceiver system of the receiving station;

The second wireless transceiver system of the receiving station is used to receive the transmitting space position information, attitude information and actual pointing angle of the transmitting station, and transmit it to the receiving synchronization system;

The receiving synchronization system transmits the spatial position information, attitude information and current actual pointing angle of the antenna to the display unit;

The display unit of the receiving station transmits the spatial position information, attitude information and the current actual pointing angle of the antenna to the display unit to display the current actual pointing angle of the transmitting station according to the received spatial position information, attitude information and antenna current pointing angle of the transmitting station Spatial position information, attitude information, and current actual pointing angle information of the antenna, and spatial position information, attitude information, and current actual pointing angle information of the antenna of the receiving station.

Further, the spatial position information of the carrier aircraft includes: longitude, latitude, and altitude of the spatial position, and the attitude data information is specifically the attitude angle of the carrier aircraft, including: yaw angle, pitch angle, and roll angle.

Further, the specific calculation process of the pointing angle when the antenna beam is aimed at the target area is as follows:

Introduce intermediate variables X, Y, N in the solution process, where

$\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span>$

$\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span>$

$\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span>$

The azimuth β is:

βX-Y

The pitch angle θ is:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Hm</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; HR</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; min</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; Hm</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; HR</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>$

Among them, Lor represents the longitude of the spatial position of the carrier aircraft, Lar represents the latitude of the spatial position of the carrier aircraft, Hr represents the altitude of the spatial position of the carrier aircraft, Lom represents the longitude of the spatial position of the target area, and Lam represents the spatial position of the target area The latitude of , Hm represents the altitude of the spatial position of the target area, and R represents the radius of the earth.

Beneficial effects of the present invention: the space synchronization device and method of the bistatic SAR of the present invention use the actual spatial positions of the transceiver platform to obtain the pointing angles of the respective antenna beams of the transceiver platform to the target area, and use The antenna server completes the beam alignment work, so that the antenna beams of the transceiver platform can be accurately aligned with the target area, realizing the space synchronization of the airborne bistatic SAR, ensuring the signal-to-noise ratio of the radar echo, and improving the accuracy of space synchronization.

Description of drawings

Figure 1 is a schematic diagram of the spatial structure of an airborne bistatic SAR.

Fig. 2 is a schematic structural diagram of the space synchronization device of the airborne bistatic SAR of the present invention.

FIG. 3 is a schematic flowchart of a space synchronization method for an airborne bistatic SAR according to the present invention.

Fig. 4 is a system structure diagram of a transmission synchronization system according to a specific embodiment of the present invention.

FIG. 5 is a system structure diagram of a receiving synchronization system according to a specific embodiment of the present invention.

Fig. 6 is a logical structure diagram of the attitude calculation module of the synchronization system in the specific embodiment of the present invention.

Fig. 7 is a logical structure diagram of the data processing module of the synchronization system in the specific embodiment of the present invention.

FIG. 8 is a logical structure diagram of the antenna server module of the synchronization system in the specific embodiment of the present invention.

Fig. 9 is a logic structure diagram of the radio receiving module of the receiving synchronization system in the specific embodiment of the present invention.

Fig. 10 is a logical structure diagram of the radio transmission module of the synchronous system of the transmitting station in the specific embodiment of the present invention.

Fig. 11 is a logical structure diagram of the display and control module of the receiving synchronization system in the specific embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

The structural diagram of the space synchronization device of the bistatic SAR of the present invention is shown in Figure 2, including a transmitting station part and a receiving station part, wherein, the transmitting station end specifically includes: a first positioning and attitude measuring system, a first antenna server , a transmitting synchronization system and a first wireless transceiver system; the receiving station end specifically includes: a second positioning and attitude measurement system, a second antenna server, a receiving synchronization system, a second wireless transceiver system and a display unit;

The first positioning and attitude measuring system is used to obtain the attitude data information and spatial position information of the carrier, and transmit the obtained information to the launch synchronization system;

The transmitting synchronization system calculates the pointing angle when the antenna beam of the transmitting station is aimed at the target area according to the spatial position obtained by the first positioning and attitude measurement system and the known spatial position of the target area, and combines the calculated pointing angle and the carrier The attitude angle of the aircraft is sent to the first antenna server;

The first antenna server controls the antenna of the transmitting station to adjust the antenna pointing according to the received pointing angle when the antenna beam of the transmitting station is aligned with the target area, and transmits the current actual pointing angle of the antenna to the transmitting synchronization system;

The second positioning and attitude measurement system is used to acquire the spatial position and the known spatial position of the target area, and transmit the acquired position information to the receiving synchronization system;

The first wireless transceiver system is used to send the spatial position information, attitude information and actual pointing angle of the transmitting station to the second wireless transceiver system;

The second wireless transceiver system is used to receive the sending space position information, attitude information and actual pointing angle of the transmitting station, and transmit it to the receiving synchronization system;

The receiving synchronization system calculates the pointing angle when the antenna beam of the receiving station is aimed at the target area according to the spatial position obtained by the second positioning and attitude measurement system and the known spatial position of the target area, and combines the calculated pointing angle and The attitude angle of the carrier aircraft is sent to the antenna server of the receiving station;

The second antenna server receives the pointing angle of the antenna beam of the receiving station transmitting station when it is aligned with the target area, controls the antenna of the receiving station to adjust the antenna pointing, and transmits the current actual pointing angle of the antenna to the receiving synchronization system;

The receiving synchronization system is also used to transmit the spatial position information, attitude information and current actual directional angle of the antenna of the transmitting station and the spatial position information, attitude information and current actual directional angle of the antenna to the display unit;

The display unit is used to display the spatial position information, attitude information and current actual directional angle of the antenna of the transmitting station and the spatial position information, attitude information and current actual directional angle of the antenna of the receiving station.

The positioning and attitude measurement system here adopts the CHA-4G strapdown attitude measuring instrument (hereinafter referred to as "the attitude measuring instrument") developed by the 26th Research Institute of China Power Group, and the antenna server adopts the server developed by the 54th Research Institute of China Power Group. , The wireless transceiver system adopts the MDS radio station produced by GE, and the processor used in the transmission synchronization system and the reception synchronization system is the FPGA of Xilinx Company's model Spantan3, using Verilog as the hardware description language, and using a 20MHz crystal oscillator.

The detailed structure of the transmission synchronization system and the reception synchronization system will be specifically described below in combination with the space synchronization method of the airborne bistatic SAR.

The flow diagram of the space synchronization method of the airborne bistatic SAR proposed in the present invention of the space synchronization device of the above-mentioned airborne bistatic SAR is as shown in Figure 3, and the specific steps are as follows:

Step 1: Obtain the spatial position information of the carrier aircraft and the attitude data information of the carrier,

The first positioning and attitude measuring system at the transmitting station and the second positioning and attitude measuring system at the receiving station obtain the spatial position information and attitude data information of the carrier aircraft, and respectively convert the acquired spatial position information and attitude data information of the carrier aircraft to Transmission to the transmission synchronization system at the transmitting station and the reception synchronization system at the receiving end.

Here, the first positioning and attitude measuring system and the second positioning and attitude measuring system are specifically the heading and attitude instrument. After the heading and attitude measuring instrument works normally, it can output the spatial position of the carrier aircraft (longitude Lor, latitude Lar, altitude Hr) and the attitude of the carrier aircraft. Angle (yaw angle, pitch angle, roll angle), the serial port protocol is RS422, the data protocol is: baud rate 115200bps, 8 data bits, 1 stop bit, no parity, and the data output cycle is 10ms/frame.

The structural diagram of the transmission synchronization system is shown in Figure 4, which specifically includes: attitude calculation module (Hz_uart_module), data processing module (Data_process_module), radio transmission module (Dt_uart_module_tx) and antenna servo module (SIFU_uart_module).

The structural diagram of the receiving synchronization system is shown in Figure 5, which specifically includes: attitude calculation module (Hz_uart_module), data processing module (Data_process_module), radio receiving module (Dt_uart_module_rx), antenna servo module (SIFU_uart_module) and display control module (XK_uart_module ).

The spatial position and attitude angle of the carrier aircraft are obtained through the attitude calculation module (Hz_uart_module) in the FPGA of the transmitting synchronization system and the receiving synchronization system, which includes the receiving baud rate selection module (speed_select_rx), serial-to-parallel module (Hz_uart_rx ) and the data register module (dat_an_Hz) three sub-modules, as shown in Figure 6.

In the receiving baud rate selection module, it is necessary to calculate the clock cycle required to receive 1-bit data in advance according to the system crystal frequency. Since the crystal oscillator used is 20MHz, the common baud rate (9600, 19200, 38400, 115200) corresponds to the clock cycle required to receive 1-bit data (1152, 576, 288, 96), and the module output is the sampling pulse of the received data (clk_bps_rx ); the serial-to-parallel module converts the received serial data (rs232_rx) into parallel data (rx_data) according to the data format of the flight attitude instrument; the data register module converts the parallel data into parallel data according to the format of the data frame Registered in each output register, including longitude (Hz_lor), latitude (Hz_lat), altitude (Hz_h), heading angle (Hz_Hangxiang), pitch angle (Hz_Fuyang), roll angle (Hz_Gundong).

Explanation: clk and rst_n in Figure 6~11 represent clock signal and reset signal respectively.

Step 2: Calculate the antenna beam pointing angle,

The transmission synchronization system of the transmitting station calculates the antenna beam pointing angle of the antenna beam of the transmitting station to the target area according to the obtained spatial position information of the terminal carrier of the transmitting station and the known spatial position information of the target area; The synchronization system calculates the antenna beam pointing angle at which the antenna beam of the receiving station is aligned with the target area based on the obtained spatial position information of the aircraft at the receiving station and the known spatial position information of the target area.

According to step 1, the synchronization system obtains the spatial position information of the carrier aircraft, and the spatial position information (longitude Lom, latitude Lam, altitude Hm) of the target area is determined before the imaging work. The synchronization system can calculate the pointing angle of the antenna beam when aiming at the target area according to the spatial position of the carrier aircraft and the spatial position of the target area.

Introduce intermediate variables X, Y, N in the solution process, where

$\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

The azimuth β is:

βX-Y(4)

The pitch angle θ is:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Hm</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; HR</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; min</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; Hm</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; HR</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Among them, Lor represents the longitude of the spatial position of the carrier aircraft, Lar represents the latitude of the spatial position of the carrier aircraft, Hr represents the altitude of the spatial position of the carrier aircraft, Lom represents the longitude of the spatial position of the target area, and Lam represents the spatial position of the target area The latitude of , Hm represents the altitude of the spatial position of the target area, and R represents the radius of the earth.

The calculation of the antenna beam pointing angle is realized by the data processing module (Data_process_module) in the FPGA. The data processing module includes three sub-modules: angle to radian module (degree_to_radian), angle calculation module (count_beta_theta) and pointing angle calculation module (radian_to_degree), as shown in Figure 7. In order to facilitate the realization of sine and cosine operations, multiplication operations, addition and subtraction operations, arctangent operations, and data storage during processing in formulas (1)~(5), Xilinx's SINCOS, MULT, ADD, and SUB are added to the data processing module , ARCTAN and RAM these six data blocks.

Since the input angle used in the SINCOS operation is in radians, the longitude (Hz_lor), latitude (Hz_lat), target longitude (M_lor) and target latitude (M_lat) obtained from the data of the attitude indicator are all in degrees Therefore, the angle-to-radian module is used to convert the input longitude and latitude into radians. The conversion method is to multiply the longitude and latitude by a conversion constant factor DTR (32-digit decimal number 1572052833). The angle to radian module converts the input longitude and latitude into radians, and then inputs it to the angle calculation module, and the angle calculation module then solves the problem according to the formula (1)~(5) according to the altitude of the platform (Hz_h) and the altitude of the target (M_h). Calculate the antenna beam azimuth angle beta_temp and the antenna beam elevation angle theta_temp.

Since the calculation result of ARCTAN is in radians, the units of the antenna beam azimuth angle beta_temp and the antenna beam elevation angle theta_temp obtained by the angle calculation module are both radians, and the antenna beam azimuth angle beta_temp and the antenna beam elevation angle theta_temp need to be converted into angles. The conversion method It is multiplied by a conversion constant factor RTD (32-digit decimal number 1201579585), and then the antenna beam azimuth angle beta and the antenna beam elevation angle theta are obtained, and the solution completion pulse (process_finish) is output.

Step 3: Send the antenna beam pointing angle calculated in step 2 to the server, and the server controls the antenna to adjust the pointing,

The transmitting synchronization system and the receiving synchronization system respectively calculate the antenna beam pointing angle of the transmitting station's antenna beam at the target area, the attitude angle of the carrier aircraft, and the antenna beam pointing angle of the receiving station's antenna beam at the target area, the carrier aircraft's The attitude angle is sent to the first antenna server of the transmitting station and the second antenna server of the receiving station, and the first antenna server and the second antenna server respectively control the antenna of the transmitting station to adjust the antenna pointing according to the received antenna beam pointing angle and the receiving station antenna to adjust the antenna pointing, the server will stabilize the antenna pointing according to the attitude angle of the carrier aircraft, and transmit the current actual pointing angle of the antenna to the transmitting synchronization system and the receiving synchronization system respectively.

The antenna servo module is divided into two parts: sending and receiving. As shown in Figure 8, the sending part completes sending the antenna beam pointing angle to the antenna server; the receiving part completes receiving the data returned by the antenna server. The serial port of the server is RS232, the data protocol is: baud rate 19200bps, 8 data bits, 1 stop bit, no parity.

The sending part includes three sub-modules: sending baud rate selection module (speed_select_tx), parallel-to-serial module (SIFU_uart_tx) and data reading module (SIFU_dat_tx). The control data output period of the antenna servo module is 100ms/frame. The sending baud rate selection module calculates the clock cycle (576) required to send 1 bit according to the actual baud rate (19200bps) of the server, and outputs the sampling pulse (clk_bps_tx) of the sending data; the data reading module converts the antenna beam azimuth (Cal_Beta ) and the antenna beam pitch angle (Cal_Theta) are sent to the parallel-to-serial module sequentially in bytes according to the data frame format of the server; the parallel-to-serial module converts the data to be sent (tx_data) into serial data (rs232_tx), Sequentially send to the serial port pin of the FPGA corresponding to the server, and output a sending completion pulse signal (SIFU_finish).

The receiving part includes three sub-modules: receiving baud rate selection module (speed_select_rx), serial-to-parallel module (SIFU_uart_rx) and data register module (SIFU_dat_rx). The data return period of the server is 100ms/frame, and the receiving baud rate selection module calculates that the baud rate of the server is 19200bps, corresponding to the clock cycle required to receive 1 bit is 576, and the module output is the sampling pulse (clk_bps_rx) of the received data; The parallel module converts the received serial data (rs232_rx) into parallel data (rx_data) according to the serial port protocol of the server; the data storage module solves the parallel data according to the data frame format of the server And store it in the two registers of antenna pointing azimuth (Local_Beta) and antenna pointing pitch angle (Local_Theta).

Step 4: Data display,

The first wireless transceiver system of the transmitting station sends the spatial position information, attitude information and actual pointing angle of the transmitting station to the second wireless transceiver system of the receiving station;

The second wireless transceiver system of the receiving station is used to receive the transmitting space position information, attitude information and actual pointing angle of the transmitting station, and transmit it to the receiving synchronization system;

The receiving synchronization system transmits the spatial position information, attitude information and current actual pointing angle of the antenna to the display unit;

The display unit of the receiving station transmits the spatial position information, attitude information and the current actual pointing angle of the antenna to the display unit to display the current actual pointing angle of the transmitting station according to the received spatial position information, attitude information and antenna current pointing angle of the transmitting station Spatial position information, attitude information, and current actual pointing angle information of the antenna, and spatial position information, attitude information, and current actual pointing angle information of the antenna of the receiving station.

The transmission synchronization system controls the MDS station of the transmitting station to start sending data to the receiving station continuously, which is realized by the radio sending module in the FPGA. The radio sending module includes a receiving baud rate selection module (speed_select_tx), a parallel-to-serial module (dt_uart_tx) and a data reading module (dt_dat_tx_) three submodules. Every time a frame of data is sent, a trigger pulse (dt_finish) is generated, and the antenna servo module (SIFU_uart_module) is triggered to send the antenna pointing angle to the antenna server of the transmitting station.

The receiving synchronization system can continuously receive the data sent by the transmitting station, which is realized by the radio receiving module (Dt_uart_module_rx) in the FPGA. The radio receiving module includes the receiving baud rate selection module (speed_select_rx) and the serial-to-parallel module (dt_uart_rx) and data storage The module (dat_an_dt) has three submodules, as shown in Figure 9. Every time a frame of data is received, a trigger pulse (Dt_start_rx) is generated, and the antenna servo module (SIFU_uart_module) is triggered to send the antenna pointing angle to the antenna server of the transmitting station.

The transmission synchronization system sends the longitude, latitude, altitude, heading angle, roll angle, pitch angle, antenna beam azimuth and antenna beam pitch angle of the transmitting station to the MDS station in a package, and the station sends it to the receiving station. The FPGA is implemented through the radio transmission module (Dt_uart_module_tx), which includes three sub-modules: the receiving baud rate selection module (speed_select_tx), the parallel-to-serial module (dt_uart_tx) and the data reading module (dt_dat_tx_), as shown in Figure 10.

The serial port of the MDS radio is RS232, and the data protocol is: baud rate 19200bps, 8 data bits, 1 stop bit, no parity. The radio module controls the data output cycle to be 100ms/frame, and the last two bytes of each frame of data are CRC check codes. The sending baud rate selection module calculates the clock cycle (576) required to send 1 bit of data according to the actual baud rate (19200bps) of the station, and outputs the sending data sampling pulse (clk_bps_tx); the data reading module takes the longitude and latitude of the transmitting station , altitude, roll angle, heading angle, pitch angle, antenna beam azimuth angle and antenna beam pitch angle are sent to the parallel-to-serial module in byte order according to the data frame format of the station; the parallel-to-serial module sends the data that needs to be sent (tx_data) is converted into serial data (rs232_tx), sequentially sent to the serial port pin of the corresponding FPGA station, and output the transmission completion pulse (dt_finish).

At the same time, the parallel-to-serial module also implements CRC check operation, and the CRC generator polynomial used is CRC-16-IBM (x16+x15+x2+1). Divide the serial data to be sent cyclically by the polynomial (11000000000000101), and finally get a 16-bit CRC check code.

The receiving synchronization system packs the spatial position information, attitude information and antenna pointing angle of the transmitting station and the receiving station and sends them to the display terminal, and the display and control software is installed on the display terminal to display the spatial position information, attitude information and Antenna pointing angle, which monitors space synchronization. The sending of packaged data is realized through the display and control module (XK_uart_module), which includes three sub-modules of sending baud rate selection module (speed_select_tx), parallel-to-serial module (XK_uart_tx) and data reading module (XK_tx_n), as shown in Figure 11 shown.

The serial port of the display terminal is RS232, the data protocol is: baud rate 19200bps, 8 data bits, 1 stop bit, no parity. The display and control module controls the data output cycle to be 100ms/frame. The sending baud rate selection module calculates the clock cycle (576) required to send 1 bit according to the actual baud rate (19200bps) of the station, and outputs the sampling pulse (clk_bps_tx) of the sending data; the data reading module sends the spatial position information of the transmitting station ( Longitude Hz_lor_dt, latitude Hz_lat_dt, altitude Hz_h_dt), attitude information (roll angle Hz_Gundong_dt, heading angle Hz_Hangxiang_dt, pitch angle Hz_Fuyang_dt), antenna pointing angle (azimuth beta, pitch angle theta) and spatial position information of the receiving station (longitude Hz_lor, Latitude Hz_lat, altitude Hz_h), attitude information (roll angle Hz_Gundong, heading angle Hz_Hangxiang, pitch angle Hz_Fuyang) and antenna pointing angle (azimuth angle Cal_Beta, pitch angle Cal_Theta) are sent to the parallel-to-serial module in sequence according to the data frame format; The serial module converts the data to be sent (XK_tx_dat) into serial data (rs232_tx), sends them sequentially to the serial port pins of the corresponding display end of the FPGA, and outputs a sending completion pulse signal (XK_finish).

Through the above steps, the antenna beams of the airborne bistatic SAR transmitting station and receiving station can be aimed at the target area, and the spatial synchronization of the bistatic SAR can be realized.

Those skilled in the art will appreciate that the embodiments described here are to help readers understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical revelations disclosed in the present invention without departing from the essence of the present invention, and these modifications and combinations are still within the protection scope of the present invention.

Claims (6)

1. A space synchronization device for bistatic SAR, including a transmitting station part and a receiving station part, wherein the transmitting station end specifically includes: a first positioning and attitude measurement system, a first antenna server, a transmitting synchronization system and a first A wireless transceiver system; the receiving station specifically includes: a second positioning and attitude measurement system, a second antenna server, a receiving synchronization system, a second wireless transceiver system, and a display unit; The first positioning and attitude measuring system is used to obtain the attitude data information and spatial position information of the carrier aircraft, and transmit the obtained information to the launch synchronization system; The transmitting synchronization system calculates the pointing angle when the antenna beam of the transmitting station is aimed at the target area according to the spatial position obtained by the first positioning and attitude measurement system and the known spatial position of the target area, and combines the calculated pointing angle and the carrier The attitude angle of the aircraft is sent to the first antenna server; The first antenna server controls the antenna of the transmitting station to adjust the antenna pointing according to the received pointing angle when the antenna beam of the transmitting station is aligned with the target area, and transmits the current actual pointing angle of the antenna to the transmitting synchronization system; The second positioning and attitude measurement system is used to acquire the spatial position and the known spatial position of the target area, and transmit the acquired position information to the receiving synchronization system; The first wireless transceiver system is used to send the spatial position information, attitude information and actual pointing angle of the transmitting station to the second wireless transceiver system; The second wireless transceiver system is used to receive the sending space position information, attitude information and actual pointing angle of the transmitting station, and transmit it to the receiving synchronization system; The receiving synchronization system calculates the pointing angle when the antenna beam of the receiving station is aimed at the target area according to the spatial position obtained by the second positioning and attitude measurement system and the known spatial position of the target area, and combines the calculated pointing angle and The attitude angle of the carrier aircraft is sent to the antenna server of the receiving station; The second antenna server receives the pointing angle of the antenna beam of the receiving station transmitting station when it is aligned with the target area, controls the antenna of the receiving station to adjust the antenna pointing, and transmits the current actual pointing angle of the antenna to the receiving synchronization system; The receiving synchronization system is also used to transmit the spatial position information, attitude information and current actual directional angle of the antenna of the transmitting station and the spatial position information, attitude information and current actual directional angle of the antenna to the display unit; The display unit is used to display the spatial position information, attitude information and current actual directional angle of the antenna of the transmitting station and the spatial position information, attitude information and current actual directional angle of the antenna of the receiving station. 2. The space synchronization device of bistatic SAR according to claim 1, wherein the space position information of the carrier aircraft includes: longitude, latitude, and altitude of the space position, and the attitude data information is specifically The attitude angle of the carrier aircraft, including: yaw angle, pitch angle, and roll angle. 3. the space synchronization device of bistatic SAR according to claim 2, is characterized in that, the specific solution process of the pointing angle when antenna beam is aimed at target area is as follows: Introduce intermediate variables X, Y, N in the solution process, where $\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span>$ $\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span>$ $\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span>$ The azimuth β is: β=X-Y The pitch angle θ is: $\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Hm</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; HR</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; min</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; Hm</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; HR</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; .</span>$ Among them, Lor represents the longitude of the spatial position of the carrier aircraft, Lar represents the latitude of the spatial position of the carrier aircraft, Hr represents the altitude of the spatial position of the carrier aircraft, Lom represents the longitude of the spatial position of the target area, and Lam represents the spatial position of the target area The latitude of , Hm represents the altitude of the spatial position of the target area, and R represents the radius of the earth. 4. A space synchronization method for bistatic SAR, comprising the steps of: Step 1: Obtain the spatial position information and attitude data information of the carrier aircraft, The first positioning and attitude measuring system at the transmitting station and the second positioning and attitude measuring system at the receiving station obtain the spatial position information and attitude data information of the carrier aircraft, and respectively convert the acquired spatial position information and attitude data information of the carrier aircraft to The transmission synchronization system transmitted to the transmitting station and the reception synchronization system at the receiving end; Step 2: Calculate the antenna beam pointing angle, The transmission synchronization system of the transmitting station calculates the antenna beam pointing angle of the antenna beam of the transmitting station to the target area according to the obtained spatial position information of the terminal carrier of the transmitting station and the known spatial position information of the target area; The synchronization system calculates the antenna beam pointing angle of the antenna beam of the receiving station to the target area according to the obtained spatial position information of the receiving station terminal carrier and the known spatial position information of the target area; Step 3: Send the antenna beam pointing angle calculated in step 2 to the server, and the server controls the antenna to adjust the pointing, The transmitting synchronization system and the receiving synchronization system respectively calculate the antenna beam pointing angle of the transmitting station's antenna beam at the target area, the attitude angle of the carrier aircraft, and the antenna beam pointing angle of the receiving station's antenna beam at the target area, the carrier aircraft's The attitude angle is sent to the first antenna server of the transmitting station and the second antenna server of the receiving station, and the first antenna server and the second antenna server respectively control the antenna of the transmitting station to adjust the antenna pointing according to the received antenna beam pointing angle and the receiving station antenna to adjust the antenna pointing, the server will stabilize the antenna pointing according to the attitude angle of the carrier aircraft, and transmit the current actual pointing angle of the antenna to the transmitting synchronization system and the receiving synchronization system respectively; Step 4: Data display, The first wireless transceiver system of the transmitting station sends the spatial position information, attitude information and actual pointing angle of the transmitting station to the second wireless transceiver system of the receiving station; The second wireless transceiver system of the receiving station is used to receive the transmitting space position information, attitude information and actual pointing angle of the transmitting station, and transmit it to the receiving synchronization system; The receiving synchronization system transmits the spatial position information, attitude information and current actual pointing angle of the antenna to the display unit; The display unit of the receiving station transmits the spatial position information, attitude information and the current actual pointing angle of the antenna to the display unit to display the current actual pointing angle of the transmitting station according to the received spatial position information, attitude information and antenna current pointing angle of the transmitting station Spatial position information, attitude information, and current actual pointing angle information of the antenna, and spatial position information, attitude information, and current actual pointing angle information of the antenna of the receiving station. 5. The space synchronization method of bistatic SAR according to claim 4, wherein the space position information of the carrier includes: the longitude, latitude, and altitude of the space position, and the attitude data information is specifically carried The attitude angle of the aircraft, including: yaw angle, pitch angle, roll angle. 6. the space synchronization method of bistatic SAR according to claim 5, is characterized in that, the specific solution process of the pointing angle when the antenna beam is aimed at the target area is as follows: Introduce intermediate variables X, Y, N in the solution process, where $\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span>$ $\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; Lom</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Lor</span>}<span\; class="notranslate">\; |</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span>$ $\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \{</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Lam</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Lar</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \}</span>$ The azimuth β is: β=X-Y The pitch angle θ is: $\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ac</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Hm</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; HR</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; min</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; Hm</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; HR</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>$ Among them, Lor represents the longitude of the spatial position of the carrier aircraft, Lar represents the latitude of the spatial position of the carrier aircraft, Hr represents the altitude of the spatial position of the carrier aircraft, Lom represents the longitude of the spatial position of the target area, and Lam represents the spatial position of the target area The latitude of , Hm represents the altitude of the spatial position of the target area, and R represents the radius of the earth.

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