CN112147587B - Radar beam azimuth center offshore calibration method - Google Patents

Abstract

The invention discloses a radar beam azimuth center offshore calibration method, which comprises the following steps: step 1, calculating a route; step 2, radar signal acquisition; step 3, calculating the azimuth corresponding to the maximum value of the signal; step 4, error judgment; and 5: adjusting a route; and 6, calculating photoelectric deviation. The radar beam calibration method disclosed by the invention is suitable for radars which are erected on the coast and are difficult to implement by the traditional calibration mode, and can enrich radar calibration means in actual environment.

Description

Radar beam azimuth center offshore calibration method

Technical Field

The invention belongs to the field of radar calibration, and particularly relates to a radar beam azimuth center offshore calibration method in the field.

Background

The measurement accuracy of the radar detection target determines the working capacity of the radar to some extent, and is a very important technical index. In practical applications, the radar measurement errors mainly include random errors and systematic errors. Random errors are usually suppressed by means of data statistics, while systematic errors need to be eliminated by some technical means.

Among the many systematic errors, beam pointing error is the most common one. The radar antenna is installed in place and is caused by the fact that the optical axis and the electric axis are not in the same direction, wherein the optical axis is a visual axis of optical equipment which is installed on the antenna and used as a shaft system reference, and the electric axis is the beam center direction of the radar antenna. Currently, the primary way to calibrate both deviations is based on a reference tower. The erection of the reference tower has strict requirements on distance and height (see Zhang Zhongsheng, Wangzhui, radar calibration technology [ M ], national defense industry publishers, 2017 and GJB 3153-. In far field conditions, the calibration tower height must be higher than the radar antenna to reduce ground multipath effects. However, for radars in certain specific environments, it is difficult to erect calibration towers around the radar site. For example, a sea clutter observation radar erected at the top of a sea island is difficult to realize in the traditional calibration mode, and a new method needs to be found.

Disclosure of Invention

The invention provides a radar beam azimuth center offshore calibration method which is used for solving the problem that a sea clutter observation radar erected at the top of a sea island cannot be calibrated by a calibration tower.

The invention adopts the following technical scheme:

the improvement of the method for calibrating the azimuth center of the radar beam at sea comprises the following steps:

step 1, calculating a route: according to the longitude and latitude LatR, LonR, height H and optical axis azimuth phi of the radar₀A downward depression angle alpha of a radar beam and a half-power beam width theta of the radar_3dBDesigning a flight path ab vertical to the direction of the optical axis, wherein the distance corresponds to the width of the irradiation area of the radar half-power beam, and the longitude and latitude of the end point of the flight path can be obtained through a Vincenty forward solution formula;

step 2, radar signal acquisition: guiding a ship to move along a course line at a constant speed through navigation equipment, carrying an electromagnetic signal receiver and a receiving antenna on the ship, ensuring that the beam center of the receiving antenna points to a radar by utilizing a ship-mounted stable platform, receiving and recording radar signals in real time, and synchronously recording track information;

step 3, calculating the azimuth corresponding to the maximum signal value: according to the time t corresponding to the maximum value of the received radar signal, finding corresponding ship longitude and latitude information LatS and LonS in the track information, and according to radar longitude and latitude LatR, LonR and Vincenty inverse solution formula, calculating real-time azimuth angle phi₁Drawing a curve of the received signal changing along with the azimuth angle;

step 4, error judgment: calculating the azimuth angle phi corresponding to the maximum value of the received signal₁And the azimuth angle phi in step 1₀If Δ φ is | φ₁-φ₀|＞θ_3dB10, then the azimuth angle phi in step 1 is determined₀Is changed to phi₁Recalculating the course and re-executing the step 2 and the step 3 to obtain the azimuth angle phi₂And calculate phi₂And the last azimuth angle phi₁So as to update a difference of | phi ═ phi₁-φ₀|＞θ_3dBThe value of delta phi in/10,

and 5: adjusting a route: after n +1 times of adjustment, the requirement that delta phi is equal to | phi is met_n-φ_n-1|≤θ_3dBAt/10 th, phi_nNamely the azimuth angle of the electric axis;

step 6, calculating photoelectric deviation: azimuth angle phi of optical axis₀Azimuth angle phi with respect to the electric axis_nThe difference of (a) is the photoelectric deviation delta phi', phi ═ phi₀-φ_n。

The invention has the beneficial effects that:

the radar beam calibration method disclosed by the invention is suitable for radars which are erected on the coast and are difficult to implement by the traditional calibration mode, and can enrich radar calibration means in actual environment.

Drawings

Fig. 1 is a schematic flow chart of a radar beam calibration method disclosed in embodiment 1 of the present invention;

fig. 2 is a diagram of the effect of the amplitude mean estimation method.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Embodiment 1, as shown in fig. 1, this embodiment discloses a radar beam azimuth center maritime calibration method, including the following steps:

step 1, calculating a route: according to the radar longitude and latitude (LatR, LonR), height H and optical axis azimuth angle phi₀A downward depression angle alpha of a radar beam and a half-power beam width theta of the radar_3dBDesigning a flight path ab perpendicular to the optical axis direction, wherein the distance corresponds to the width of a radar half-power beam irradiation area as shown in fig. 2, and the longitude and latitude of a flight path endpoint can be obtained through a Vincenty forward solution formula;

step 2, radar signal acquisition: guiding a ship to move along a course line at a constant speed through navigation equipment, carrying an electromagnetic signal receiver and a receiving antenna on the ship, ensuring that the beam center of the receiving antenna points to a radar by utilizing a ship-mounted stable platform, receiving and recording radar signals in real time, and synchronously recording track information;

step 3, calculating the azimuth corresponding to the maximum signal value: according to the time t corresponding to the maximum value of the received radar signal, finding corresponding ship longitude and latitude information (LatS, LonS) in the track information, and according to radar longitude and latitude (LatR, LonR) and Vincenty inverse solution formula, calculating real-time azimuth angle phi₁Drawing a curve of the received signal changing along with the azimuth angle;

step 4, error judgment: calculating the azimuth angle phi corresponding to the maximum value of the received signal₁And the azimuth angle phi in step 1₀If the error is equal to | phi ═ phi₁-φ₀|＞θ_3dB10, then the azimuth angle phi in step 1 is determined₀Is changed to phi₁Recalculating the course and re-executing the step 2 and the step 3 to obtain the azimuth angle phi₂And calculate phi₂And the last azimuth angle phi₁So as to update a difference of | phi ═ phi₁-φ₀|＞θ_3dBThe value of delta phi in/10,

and 5: adjusting a route: after n +1 times of adjustment, the error delta phi is equal to | phi_n-φ_n-1|≤θ_3dBAt/10 th, phi_nNamely the azimuth angle of the electric axis;

step 6, calculating photoelectric deviation: azimuth angle phi of optical axis₀Azimuth angle phi with respect to the electric axis_nThe difference of (a) is the photoelectric deviation delta phi', phi ═ phi₀-φ_n。

Claims (1)

1. A radar beam azimuth center offshore calibration method is characterized by comprising the following steps:

step 1, calculating a route: according to the longitude and latitude LatR, LonR, height H and optical axis azimuth phi of the radar₀A downward depression angle alpha of a radar beam and a half-power beam width theta of the radar_3dBDesigning a flight path ab vertical to the direction of the optical axis, wherein the distance corresponds to the width of the irradiation area of the radar half-power beam, and the longitude and latitude of the end point of the flight path can be obtained through a Vincenty forward solution formula;

step 2, radar signal acquisition: guiding a ship to move along a course line at a constant speed through navigation equipment, carrying an electromagnetic signal receiver and a receiving antenna on the ship, ensuring that the beam center of the receiving antenna points to a radar by utilizing a ship-mounted stable platform, receiving and recording radar signals in real time, and synchronously recording track information;

step 3, calculating the azimuth corresponding to the maximum signal value: according to the time t corresponding to the maximum value of the received radar signal, finding corresponding ship longitude and latitude information LatS and LonS in the track information, and according to radar longitude and latitude LatR, LonR and Vincenty inverse solution formula, calculating real-time azimuth angle phi₁Drawing a curve of the received signal changing along with the azimuth angle;

step 4, error judgment: calculating the azimuth angle phi corresponding to the maximum value of the received signal₁And the azimuth angle phi in step 1₀If Δ φ is | φ₁-φ₀|＞θ_3dB10, then the azimuth angle phi in step 1 is determined₀Is changed to phi₁Recalculating the course and re-executing the step 2 and the step 3 to obtain the azimuth angle phi₂And calculate phi₂And the last timeAzimuth angle phi₁So as to update a difference of | phi ═ phi₁-φ₀|＞θ_3dBThe value of delta phi in/10,

and 5: adjusting a route: after n +1 times of adjustment, the requirement that delta phi is equal to | phi is met_n-φ_n-1|≤θ_3dBAt/10 th, phi_nNamely the azimuth angle of the electric axis;

step 6, calculating photoelectric deviation: azimuth angle phi of optical axis₀Azimuth angle phi with respect to the electric axis_nThe difference of (a) is the photoelectric deviation delta phi', phi ═ phi₀-φ_n。

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