JPH0378595B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ground ranging radar mounted on an aircraft or the like to measure the distance to the ground, and particularly to improving the accuracy thereof.

[Conventional technology]

Figure 3 is a diagram showing the configuration blocks of a conventional ground ranging radar. In the figure, 1 is a phased array antenna, 2 is an excitation/receiver, 3 is a beam controller, 4 is a navigation sensor, and 5 is a diver. The angle input section 6 is a signal processor. Further, 10 in the signal processor 6 is a beam data production section, and a beam data switching section 1
1, addition and subtraction 12a, 12b, offset amount calculation 13, and distance measurement angle calculation 14.

A conventional ground ranging radar is configured as described above. For example, the transmitted wave from the excitation/receiver 2 is irradiated onto the ground or sea surface in the ranging direction via the phased array antenna 1, and the reflected wave is reflected by the phased array antenna 1. It becomes a received wave via the aided array antenna 1, and is converted into a digital signal by the excitation/receiver 2. At this time, the beam control unit 3 receives beam directivity angle data from the beam data production unit 10 and controls the main beam direction of the phased array antenna 1 up and down (0.3 to 0.6 times the main beam width with respect to the ranging angle). The signal processor 6 stores the received wave of the digital signal in the range memory corresponding to the vertical direction of the main beam, and the two received wave data stored in this range memory are sent to the calculation section. By combining (subtracting) with , a null point is formed at the distance measurement point,
Distance measurement is achieved by detecting or calculating the distance to this null point.

Note that the beam data calculation section 1 in the signal processor 6
0, the phased array antenna 1 is set based on the attitude angle data from the navigation sensor 4 and the ranging dive angle data set by the operator etc. from the dive angle input unit 5.
beam directivity angle data θ ₊ , θ ₋ ) are calculated and sent to the beam controller 3.

Here, we will discuss the fourth example of operation of ground ranging radar.
Supplement with figures. In FIG. 4, 20 is a ground ranging radar, 21 is an aircraft, 22 is the ground or sea surface, 23 and 24 are main beams of the phased array antenna 1 switched vertically, 25 is a ranging axis, 2
6 is the horizontal axis, 27 is the phased array antenna 1
mechanical boresight axis, 28 is the ranging dive angle, 2
9 is the distance measurement angle. In this case, the ranging angle 29 is the angle between the mechanical boresight axis 27 and the ranging axis 25.
Main beams 23, 24 switched up and down relative to
By combining (subtracting) the received signals of Distance measurement between the distance radars 20 is possible.

[Problem that the invention seeks to solve]

As mentioned above, the conventional ground ranging radar calculates the distance by signal processing of the received signals of the two main beams 23 and 24, which are switched up and down with respect to the ranging angle 29. When it becomes large, the null angle 30 and distance measurement angle 29 of the composite signal 31 will change as shown in FIG. 5 due to the shape difference between the two main beams 23 and 24.
deviation (Δφ=θ _B /2, tanθ ₀・tanθ _B /2, however,
θ ₀ is the distance measurement angle, and θ _B is the main beam width at the distance measurement angle. ), and there was a problem that the distance measurement accuracy was poor.

This generation was made to solve this problem, and the purpose is to obtain a ground ranging radar with good ranging accuracy.

[Means for solving problems]

In the ground ranging radar according to the present invention, the switching amount of the main beam, which is switched up and down with respect to the ranging angle, is changed in accordance with the ranging angle.

[Effect]

In this invention, since the received signals of the two main beams switched up and down are controlled to be equal at the distance measurement angle, the distance measurement angle 29 and the null point angle 30
match, allowing accurate distance measurement.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention, and numerals 1 to 5 in the figure are exactly the same as the conventional ground ranging radar described above. Reference numeral 6a denotes a signal processor, which differs from the conventional one in that a correction amount calculation 15 and an addition 12a are added to the beam data calculation section 10a.

By this correction amount calculation 15 and the two additions 12a, the beams of the main beams 23 and 24 are adjusted such that the received signals of the main beams 23 and 24, which are switched up and down with respect to the distance measurement angle 29, are equal at the distance measurement angle 29. Directional angle is corrected.

Here, an example of correction amount calculation will be shown.

If the distance measurement angle is θ ₀ and the main beam width at the distance measurement angle is θ _B , then in order to equalize the received signals of the main beam at the distance measurement angle, the correction value Δθ is becomes. (However, the beam switching interval is set to θ _B. ) In the ground ranging radar configured as described above, the beams are set so that the received signals of the main beams 23 and 24 switched vertically are equal at the ranging angle 29. Since the directivity angle data (θ ₊ , θ _- ) is controlled, the second
As shown in the figure, the distance measurement angle 29 and the null point angle 30 of the composite signal 31 match, that is, a null point is formed at the distance measurement angle, and accurate distance measurement is made possible by detecting the distance of the null point. It's on.

By the way, in the above explanation, this invention was described as a system in which the transmitting and receiving main beams are switched up and down with respect to the ranging angle. Needless to say, it is also possible to use a method in which the main beam is switched up and down and the other main beam is directed at the distance measurement angle.

〔Effect of the invention〕

As explained above, this invention can form a null point for signal processing at the distance measurement point by a simple method of changing the switching amount of the main beam that switches up and down depending on the distance measurement angle, and the distance measurement accuracy can be improved. It has the effect of improving.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing characteristics of the present invention, and FIG. 3 is a block diagram showing a conventional ground ranging radar.
Figure 4 shows an example of the operation of ground ranging radar, Figure 5
The figure is a diagram showing the characteristics of a conventional ground ranging radar. In the figure, 1 is a phased array antenna;
2 is an excitation/receiver, 3 is a beam controller, 4 is a navigation sensor, 5 is a dive angle input section, 6, 6a is a signal processor, 10, 10a is a beam data calculation section, 11
is beam data switching, 12a and 12b are addition and subtraction, 13 is offset amount calculation, 14 is distance measurement angle calculation, 15 is correction amount calculation, 20 is ground ranging radar,
21 is an aircraft, 22 is the ground or sea surface, 23, 24
are the upper and lower main beams, 25 is the ranging axis, 26 is the horizontal axis, 27 is the mechanical boresight axis, 28 is the ranging dive angle, 29 is the ranging angle, 30 is the null point angle, 31
is a composite signal. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A phased array antenna that forms an entrance and exit for transmitted waves and received waves in space, an excitation/receiver that forms a source of transmitted waves and converts received waves into digital signals, and a phased array antenna that forms an entrance and exit for transmitted waves and received waves in space; A beam controller that controls the beam direction and shape of the phased array antenna, a navigation sensor that detects the attitude angle of the phased array antenna, a dive angle input unit that inputs the ranging dive angle, and the vertical direction of the main beam. A range memory for storing the received wave of a digital signal corresponding to The signal processor is equipped with a signal processor that calculates a ranging angle based on the attitude angle data and dive angle data from the navigation sensor (however, the ranging angle is based on the mechanical angle of the phased array antenna). (It is the angle between the boresight axis and the ranging axis.) Beam data switching to switch the main beam of the phased array antenna up and down at predetermined intervals for calculation and ranging angle, and A ground-based antenna characterized by comprising a beam data production section for calculating the offset that forms the basis of switching, and calculating the correction amount for making the received signals of the main beam switched up and down equal at the ranging angle. Distance radar.