JPS6061668A - Radar equipment - Google Patents

Abstract

PURPOSE:To distinguish the target from clutters with a simple construction by finding correlation of signal outputs between a plurality of band-pass filters for detecting Doppler frequencies. CONSTITUTION:A signal received with an antenna 1 is amplified with a receiver 2 and inputted into a plurality of bandpass filters 3 to meet the desired Doppler band range. Outputs of the band-pass filters 3 are inputted into a clutter detector 5 and a signal interrupter 6. The clutter detector 5 detects the outputs of the band-pass filter 3 to identify clutters by finding correlation of received signals based on the frequency. When a clutter is detected, the transmission of signals to the detector 4 from the band-pass filters 3 is blocked with the signal interrupter 6.

Description

DETAILED DESCRIPTION OF THE INVENTION This is a method for identifying and removing echoes received by a radar device as moving targets or clutter.Pulsed flag device? Shown in Figure 1. In Figure 1, ill #rJ antenna, +21 if +1' K
The m-connected receiver (3) is a detector connected to each of the plurality of bandpass filters f41 u 131 connected to (2).

Next, the operation will be explained. In the pulsed toggle radar device shown in FIG. 1, a signal received by an antenna (1) is amplified to a required level by a receiver (2), and a plurality of bandpass filters (3) satisfying a desired Doppler band are used. is input. The output of each bandpass filter is sent to a detector (4
), and the presence or absence of a signal is detected for each Doppler frequency.

What if the above-mentioned pulsed Doppler radar is installed on an HTW aircraft and detects all targets approaching from behind? think. Second
In the figure, the target has a positive Doppler shift (+fdt) 'i as it approaches the aircraft. Next, clutter can be received by the main rope from the antenna to the rear of the aircraft.
-fclc), the monopole received in the backlobe (
+fdc) respectively. These Kedoplar frequencies? Figure 3 shows what is plotted on the horizontal axis. As shown in the figure, there is a significant difference in the appearance of the received signal on the frequency axis [11] between the target and the clutter.

This departure (7) σAboard the aircraft mentioned above
In a pulsed toggle radar device that detects all approaching targets, how targets and clutter appear on the Dob2 frequency axis VC
The aim is to identify targets and clutter and remove clutter using a simple additional device.

Purchase this invention? It is shown in Figure 4. In the figure, (1)
- (4) are completely opposite to conventional pulsed Doppler radar devices. ill, +61 is an additional circuit to the pulsed Doppler radar device in this invention, and (5) is (
3) is a clutter detector connected to each bandpass filter, and (6) is a plurality of signal interrupters connected to (3) 4 and (5) Vcl#:.

As shown in FIG. 3, the Doppler shift of the received 1H signal from the target is determined by the relative speed with respect to the target aircraft, so the frequency spread is extremely small.

On the other hand, the signal received from the clutter is determined by the relative velocity VC between the aircraft and the ground surface, but since the Doppler shift differs depending on the angle at which the aircraft is viewed from the ground surface, the spread on the frequency axis becomes extremely large.

From the above, in the clutter detector (5) in Figure 4, by detecting the output of each Doppler filter and taking the correlation on the frequency axis of the received signal, if there is a signal over a wide range of frequencies, it is determined to be clutter. There is. In this way, when it is determined that clutter is present, the blank pulse sending signal for blocking the filter signal is completely removed from each of the signal breakers (5) and (6).

As described above, according to the present invention, a clutter removal device can be constructed without increasing the scale of a conventional pulsed Doppler radar device.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional pulsed Doppler radar device, Fig. 2 is an explanatory diagram of Doppler shift depending on the arrival direction of received waves,
FIG. 3 is an explanatory diagram showing how received waves appear on the frequency axis, and FIG. 4 is a block diagram showing an embodiment of the radar device according to the present invention. In the figure, fil ij antenna, (2) is the receiver, (
3) is a band pass filter, (4) is a detector, (51 is a vine detector, and (6) is a signal breaker. The same reference numerals in each figure indicate the same or corresponding parts. Agent: Masuo Oiwa Figure 1 Figure 2 Figure 3 Dobra I Control Branch [Dear Commissioner of the Japan Patent Office 1. Indication of the case Patent Application No. 170674/1982 2 Name of the invention Radar device 3 To Hitoshi Katayama, the representative of the Ministry making the amendment Part 4 , Agent 5, Subject of amendment 6, Contents of amendment (1) The description will be corrected as follows. (2) Figure 2 of the drawings will be corrected as shown in the attached sheet. 7. List of attached documents (1) Drawings (Figure 2) 1 or more copies

Claims (1)

[Claims] Multiple bandpass filters are used to detect the Doppler frequency of the signal received by the antenna, the correlation of the signal output between these bandpass filters is determined, and the reception on two frequency axes determines whether the signal is a moving target or clutter. A radar device equipped with a clutter detector that identifies by intensity.