KR0181419B1 - Rotating wing aircraft detection apparatus and method thereof - Google Patents

Abstract

The present invention relates to an apparatus and method for detecting a low speed rotary wing aircraft of a detection radar, and more particularly, to an apparatus and method for detecting a rotary wing aircraft moving at a low speed.

An apparatus for detecting a rotorcraft aircraft moving at a low speed by detecting the magnitude of a signal reflected from a receiver for the purpose of the present invention, the target distance is calculated to calculate the target within a predetermined distance is the lowest speed in the filter unit When the outputs of the two filters are ORed together, and the target is calculated over a predetermined distance, the output of the rotorcraft aircraft detection signal is output by logically multiplying the outputs of the two slowest filters in the filter unit.

As described above, according to the present invention, the detection capability of the low speed moving rotorcraft can be improved by appropriately applying the logic decision of the Doppler filter 1 and the Doppler filter n which are the signal processing methods used for detecting the rotorcraft in the radar according to the distance. Can be improved.

Description

Low speed rotary wing aircraft detection device and method thereof

1 is a block diagram showing a detection apparatus for a fixed wing aircraft and a rotorcraft aircraft by a conventional pulsed Doppler radar.

2 is a block diagram showing a detailed configuration of the signal processor of FIG.

FIG. 3 shows the band-by-band configuration of the Doppler filters 1, 2, and n (218, 220, 222) of FIG.

4 is a waveform diagram showing the spectrum occurring in the axis of the body and wing of the rotorcraft.

5 is a block diagram showing a low speed rotary wing aircraft detection apparatus of the detection radar according to the present invention.

6 and 7 are block diagrams showing detection determination logic for determining rotorcraft aircraft detection according to the target distance calculator of FIG.

The present invention relates to an apparatus and method for detecting a low speed rotary wing aircraft of a detection radar, and more particularly, to an apparatus and method for detecting a rotary wing aircraft moving at a low speed.

In general, there are many types of radars for detecting aircraft, and largely fixed-wing aircraft and rotating wing aircraft can be detected.

1 is a block diagram showing a detection apparatus for a fixed wing aircraft and a rotorcraft aircraft by a conventional pulsed Doppler radar.

1 is composed of a signal generator and synchronizer 140, a transmitter 130, a radar 120 and a flying object 110, a receiver 170, a signal processor 160, and an indicator 150. .

As shown in FIG. 1, the signal generator and synchronizer 140 generates a microwave signal having a stable frequency toward the aircraft 110 in flight in the sky. The transmitter 130 makes the signals provided by the signal generator and synchronizer 140 large enough to send them far into the air. In this case, the transmitter 130 must always maintain the coherent characteristic of the signal so that accurate information of the phase can be known.

The antenna 120 radiates a signal from the transmitter 130 into space. The signal coming in through the antenna 120 and hitting a target such as an airplane 110 is input to the receiver 170, which has a sufficient stability to produce a low frequency signal in the signal processor 160.

The signal processor 160 performs various signal processing to enable detection with a signal reflected from the flying object 110 flying in the sky.

2 is a block diagram showing a detailed configuration of the signal processor 160 of FIG.

2 shows an analog-to-digital converter 214 for converting a received signal, a target distance calculator 216, a Doppler filter 1, 2, n (218, 220, 222), signal discriminators 1, 2, 3 (224, 226, 228), AND gate 230, and the OR gate 232.

As shown in FIG. 2, the spectral signal of the received target is converted into a digital signal by the analog-digital converter 214 so that the Doppler fillers 218, 220, and 222 can filter the Doppler frequency by band. do. The Doppler filters 218, 220, and 222 are connected by using n pieces in parallel to classify targets at respective speeds, and the signals filtered by the bands in the Doppler filters 218, 220, and 222 are classified by the signal discriminator 224,. 226 and 228 to discriminate noise from signals and perform final detection for each speed. That is, the values from the signal discriminator 1 224 and the signal discriminator n 228 are logically multiplied at the AND gate 230 to detect the rotorcraft (eg, the helicopter) 250, and the signal discriminator 1 ( 224, the signal discriminator 2 226, and the values from the signal discriminator n 228 are ORed at the OR gate 232 to detect the fixed wing aircraft 252, and each signal discriminator 224, 226, 228. The flight target signals 240, 242, and 244 detected for each speed from each other are output. The target distance calculator 216 also continuously calculates the target distance from the signal output from the analog-digital converter 214.

FIG. 3 shows the band-specific configuration of the Doppler filters 1, 2, and n (218, 220, 222) of FIG.

The x-axis of FIG. 3 is velocity v, the y-axis is amplitude, and is composed of Doppler filter 1 310, Doppler filter 2 320, Doppler filter 3 330, and Doppler filter n 340.

Doppler filter 1 310 and Doppler filter n 340 are the lowest speed filters.

In this case, each Doppler filter has a constant Doppler frequency that represents the difference between the transmission frequency and the reception frequency of the wave source generated by the time change of the distance between the wave source and the observation point.

4 is a waveform diagram showing the spectrum occurring in the axis of the body and wing of the rotorcraft.

In FIG. 4, the x-axis is velocity v, the y-axis is amplitude, 410 is a reflection signal of the body, and 420 is a hub reflection signal of the wing.

Looking at the spectrum from a rotorcraft (for example, a helicopter), the spectrum 410 reflected from the body during flight of the rotorcraft is near zero velocity and the spectrum 420 reflected from the wing axis is a very low spectrum. The Doppler filter 1 310 and the Doppler filter n 340 which are the low speed filters of the Doppler filter of FIG.

Therefore, the spectrum reflected from the axis of the rotorcraft is perceived as the target only when the Doppler filter 1 310 and the Doppler filter n 340 of FIG. 3 are simultaneously detected.

The decision for the final detection of the conventional rotorcraft aircraft is to detect the output value from the Doppler filter 1 218 and the detection value output from the Doppler filter n 222 as shown in FIG. Determine by logical multiplication by

However, when the rotorcraft is moving at a low speed, the spectrum of the reflected signal of the hub of FIG. 4 is shifted left and right, thereby leaving the Doppler filter 1 and the Doppler filter n.

It is therefore an object of the present invention to provide an apparatus and method for causing the spectrum from the axis to be detected by the OR of the Doppler filters as the rotorcraft moves at low speeds.

In order to achieve the object of the present invention, the present invention is a device for detecting a rotary wing aircraft moving at a low speed by detecting the magnitude of the signal reflected from the receiver, the analog-to-digital conversion of the spectral signal received from the rotor blade aircraft A digital conversion unit; A filter unit filtering the digital signal output from the analog-digital converter by a plurality of band filters for each speed; An AND product for performing an AND operation on the outputs of the two slowest filters in the filter unit to output a rotorcraft aircraft detection signal; A logic summation unit configured to logically sum the outputs of the two lowest speed filters at the filter unit and output a rotorcraft aircraft detection signal; And a target distance calculator configured to calculate a target distance from the signal output from the analog-digital converter and enable the logical product and the logical sum according to the distance.

In accordance with another aspect of the present invention, there is provided a method for detecting a rotorcraft according to a distance by a detection radar, the apparatus for detecting a rotorcraft moving at a low speed by detecting a magnitude of a signal reflected from a receiver. An analog-to-digital converter for analog-to-digital converting a spectral signal received from the rotorcraft; A filter unit filtering the digital signal output from the analog-digital converter by a plurality of band filters for each speed; When a target is calculated within a predetermined distance by calculating a target distance from the signal output from the analog-to-digital converter, the axial force is logically summed between the two slowest filters in the filter unit, and the target is calculated when the target is calculated over a predetermined distance. And a target distance calculation unit for outputting the rotorcraft aircraft detection signal by ANDing the outputs of the two lowest-speed filters in the unit.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

5 is a block diagram showing a low speed rotary wing aircraft detection apparatus of the detection radar according to the present invention.

5 is an analog-digital converter 514 for analog-digital converting a received signal, a Doppler filter 1, 2, n (518, 520, 522) for filtering a signal output from the analog-digital converter 514, Signal discriminators 1, 2, n (524, 526, 528) for discriminating and outputting signals from signals output from the Doppler filters 1, 2, n (518, 520, 522), the signal discriminators 1, and n ( Logic gate 530 outputs the detection signal 550 by ANDing the signals output from 524 and 528, and output signals from the signal discriminators 1 and n (524 and 528) to OR the rotorcraft detection signal ( An AND gate 532 for outputting a 550 and an AND gate 530 for outputting a rotorcraft aircraft detection signal 550 by ORing the output signals from the signal discriminators 1, 2, and n (524, 526, 528). Logic sum gate 552, the target distance is calculated by the signal output from the analog-to-digital converter 514 The target distance to a block in the logical AND gate 530 and OR gate 532 comprises a calculator 516.

As shown in FIG. 5, the spectral signal 510 received from the wing shaft of the rotorcraft is converted into a digital signal via an analog-to-digital converter 514. In addition, the converted digital signal is detected by the Doppler filter 1 518, the Doppler filter 2 520, and the Doppler filter n 522 to classify the target at each speed, and the signal detected by each filter is the signal discriminator 1 524, signal discriminator 2 526, and signal discriminator n 528 are detected and detected as detection signals corresponding to each filter. The detection signals output from the signal discriminator 1 524 and the signal discriminator n 528 are OR'd by the OR gate 532 to detect the rotorcraft 550.

Therefore, the detection capability of the rotorcraft aircraft is detected by either Doppler filter 1 or Doppler filter n, which is a low speed filter of the Doppler filter, by logically combining the Doppler filter 1 518 and the Doppler filter n 522 even when the aircraft moves at a low speed. Here, in the Doppler filter 1 518 or the Doppler filter n 522, the clutter, which is an undesired reflection signal from a fixed object such as an acid or a field, can increase, and there is also a possibility of the loss of the target.

Therefore, since the influence of clutter is large within a certain distance, the logical product of the Doppler filter 1 518 and the Doppler filter n 522 is applied by the AND gate 530 only in this range.

Accordingly, as shown in FIG. 5, the spectral signal output from the analog-to-digital converter 514 is calculated by the target distance calculator 516 so that the AND gate 530 and the OR gate 532 are calculated according to the distance. Enable

6 and 7 are block diagrams showing detection determination logic for determining rotorcraft aircraft detection according to the target distance calculator of FIG.

6 is decision logic when the aircraft is within a certain distance, and the Doppler filter 1, 2, n (610, 620, 630) that filters the signal, and the signal output from the Doppler filter 1, n (610, 630) Logic sum gate 640 for performing a logical multiplication and outputting the rotor blade detection signal 642, and outputting the fixed wing aircraft detection signal 652 by performing an OR on the signals output from the Doppler filters 1, 2, n (610, 620, 630). The OR gate 650 is formed.

7 is a decision logic when the aircraft is over a certain distance, and the signals output from the Doppler filters 1, 2, n (710, 720, 730) and the Doppler filters 1, n (710, 730) that filter the signal. And OR of the logical product gate 740 for outputting the rotorcraft aircraft detection signal 742 and the signals output from the Doppler filters 1, 2, n (710, 720, 730) to obtain the fixed-wing aircraft detection signal 752. It consists of a logic sum gate 750 to output.

For example, as shown in FIG. 6, when the aircraft is detected within a predetermined distance (4 to 5 km) by the target distance calculator 516 of FIG. In order to increase the probability of detection of the Doppler filter 1, the signals output from the n (610, 630) are ORed (OR) 640 to detect the rotorcraft.

In addition, as shown in FIG. 7, the Doppler filter 1, in order to minimize the influence of the clutter when the aircraft is detected at a predetermined distance (4 to 5 km) or more by the target distance calculator 516 of FIG. A rotary wing aircraft is detected by performing a logical AND 740 on a signal output from n (710, 730).

In order to optimize the detection decision logic (logical sum (OR) and logical product (AND)) over distance, it is necessary to consider that the size of the reflected signal is large at short distance and weak at long distance.

Thus, the sensitivity control element (not shown) that automatically adjusts the magnitude of the reflected signal uses silicon (Si) -silicon (Si) diodes that are less affected by clutter.

As described above, according to the present invention, the detection capability of the low speed moving rotorcraft can be improved by appropriately applying the logic decision of the Doppler filter 1 and the Doppler filter n which are the signal processing methods used for detecting the rotorcraft in the radar according to the distance. Can improve.

Claims (3)

An apparatus for detecting a rotorcraft aircraft moving at a low speed by detecting the magnitude of a signal reflected from a receiver, the apparatus comprising: an analog-digital converter for analog-to-digital converting a spectral signal received from the rotorcraft; A filter unit filtering the digital signal output from the analog-digital converter by a plurality of band filters for each speed; The target distance is calculated using the signal output from the analog-digital converter, and if a target is calculated within a predetermined distance, the output of the two slowest filters in the filter unit is ORed. And a target distance calculator for outputting the rotorcraft aircraft detection signal by ANDing the outputs of the two slowest filters in the unit. The low speed rotary wing aircraft detection apparatus according to claim 1, wherein a silicon (Si) -silicon (Si) diode is used as a sensitivity control element of the reflected signal. A method for detecting a rotorcraft aircraft according to a distance by a detection radar, the method comprising: calculating a target distance using a spectrum output from the rotorcraft; A logical sum step of outputting the rotorcraft aircraft detection signal by ORing the outputs of the two slowest filters when the target is calculated within a predetermined distance in the target distance calculation step; And detecting the low speed rotary wing aircraft of the detection radar, when the target is calculated in the target distance calculation step, outputting the rotary wing aircraft detection signal by logically multiplying the outputs of the two lowest speed filters. Device.