JPS6398580A - Radar equipment - Google Patents

Abstract

PURPOSE:To enable a distant ship to be detected by detecting and displaying the peak value of data obtained by dividing the signals received by the radar of a ship for displaying detection signals by the receiving signals for transmission signals of the radar of another ship received by a nondirectional antenna. CONSTITUTION:While revolving the antenna A of a radar 1, a received wave is displayed and scanned to display image signals on a display 10. A radar wave from another ship is received a nondirectional antenna C arranged near the antenna A. Prescribed frequency signals are extracted from this received wave by a filter 15, logarithmically amplified 18, shaped 22 and inputted to an AND circuit 23. Further, the intermediate frequency of a radio wave transmitted from and received by one's own ship is logarithmically amplified 17, shaped 21 and inputted to the AND circuit 23. While both the amplifiers 17 and 18 produced their outputs at the same time, a switch 20 is closed. The output of both the amplifiers 17 and 18 differentially amplified (substantially divided) 19, a peak value is detected 24, display signals are formed 25 and displayed 10. Thus, the other distant ship can be detected.

Description

[Detailed Description of the Invention] (Industrial Applicability) The present invention receives radio wave pulses from another ship's radar, and displays the received wave direction on the screen of own ship's radar together with the normal radar signal. Regarding radar equipment.

(Prior art) A device that combines a direction finder and a radar is known as a device that displays the direction of other ships on a radar screen, mainly from the viewpoint of safe navigation (Japanese Patent Publication No. 49-22154, Utility Model No. 5
7-139877).

(Problems to be Solved by the Invention) All of the above devices require a direction finder, so
The equipment requires cost and is also large in size.

(Means for Solving the Problems) The present invention has been made in view of the above, and is provided with an omnidirectional antenna that receives radio wave pulses from another ship's radar on a radar configured to display a target signal. , a differential amplifier circuit that extracts a signal obtained by dividing the signal received by the radar by the signal received by the omnidirectional antenna, a switch that passes the divided signal only during a period when both of the received signals are obtained, and a switch output signal. The present invention proposes a radar device that includes a detection circuit that detects the peak time of , and a display signal forming circuit that forms a display signal when the detection circuit is present.

(Function) In Figure 2, if another ship's radar antenna B is transmitting radio wave pulses without rotating, the strength of the radio waves reaching own ship's Sinota antenna A is determined by the number of rotations of antenna B and its direction. Due to its characteristics, it changes over time.

Let this strength be ta(t).

Also, when receiving the radio waves with antenna A, antenna A
A temporal change occurs in the directivity in the direction of other ship B due to the rotation speed and directivity characteristics of
1:) Proportional to xrA(t).

Now, prepare an omnidirectional antenna C near the antenna, and use the antenna C to receive radio waves from the antenna B.
The strength of the received signal is proportional to fB(t).

Therefore, by dividing the received signal power at antenna A by the received power at antenna C, a signal proportional to fA(t) can be obtained. When the peak of this signal is detected, the direction can be known by displaying a predetermined signal or mark on the display.

(Embodiment) FIG. 1 shows a circuit configuration showing an embodiment of the present invention. In the figure, the part indicated by the dashed line is a normal radar, where A is a radar antenna, and 2 is a transmission pulse generation circuit that forms transmission pulses based on a regular periodic trigger pulse from the trigger generation circuit 3. However, in the present invention, since the problem is the reception characteristic fA(t) of own ship's radar, it does not matter whether or not there is transmission6.
4 is a transmission/reception switching circuit, 5 is a high frequency amplification circuit, 6 is a mixer that mixes the output signal of the high frequency amplification circuit 5 and the signal from the local oscillator 7 to form an intermediate frequency, and 8 is an intermediate frequency that forms a video signal. The amplifier circuit 9 is a display scanning circuit for displaying a video signal on the screen of the display device IO. The above-mentioned tri-force pulse is sent to the display scanning circuit 9 and used for forming scanning signals and the like. 11 is the scanning direction of the display lO and the antenna A
This is a rotation synchronization circuit that synchronizes and rotates the pointing direction.

As shown in FIG. 2, C is an omnidirectional antenna that is placed near the radar antenna A and receives radio waves in the band used by the radar, and 12 is a high frequency amplification circuit.

13 is a mixer that mixes the output signal of the high frequency amplifier 12 and the signal from the local oscillator 14 to form an intermediate frequency, and 15 is a filter that extracts only a predetermined frequency signal from the mixed output.

There are a plurality of frequencies used by the radar, and it is preferable that the filter 15 output can be obtained for each of them. Therefore, the oscillation frequency of the local oscillator 14 can be varied by the tuning circuit 16.

17. 18 is the base of logarithm, that is, a logarithmic amplifier with the same characteristics as the value of output/manpower, the manpower to logarithm amplifier 17 is k+f+ (t) the manpower to logarithm amplifier 18 is k2fA(t) (k+, k2 is proportional constant), then the output V of the logarithmic amplifier 17 is logk lf + (
t) The output V2 of the logarithmic amplifier 18 is logk2fa (
t) These outputs are manually input to the differential amplifier 19 to generate vl-2.
When we obtain V+ −V2= logk+f+ (t) −1ogk
2fe(t)=log(k+/2)(f+(t)/
fn(t,)), L(t) = fA(t)
From f[, (t)), V, -V2 becomes a logarithmic signal of fx(t,). This is because: (1) By processing the signal with a logarithmic amplifier, the division of both signals requires only difference processing (at the differential amplifier 19), and (2) The detection characteristics are not influenced by fn(j) and are exclusively based on fA(t). This means that the direction of the other ship coincides with the direction in which the antenna A points at the peak of the output signal of the differential amplifier 19 (strictly speaking, after passing through the switch 20).

Now, the input to the logarithmic amplifier 18 is the narrow band filter 15.
However, since the input to the logarithmic amplifier 17 is only passed through the broadband amplifier circuit 5, it is a radar signal of multiple frequencies and a reflected signal from own ship's radar. are mixed. Reference numeral 20 denotes a switch for selectively extracting only the above-mentioned specific frequency or other ship's radar signal, which is switched and controlled by shaping circuits 21 and 22 and an AND circuit 23.

In FIG. 3, signal a indicates the output of logarithmic amplifier 17, signal S indicates the output of logarithmic amplifier 18, and signal C indicates the output of switch 20. The signal is a radar signal from another ship.

Therefore, among the signals a, A at the same timing as the signal A
,, A2. A3... indicates another ship's radar signal.

The shaping circuits 21 and 22 shape the signals a and b into 1-bit pulse signals and guide them to the AND circuit 23. The AND circuit 23
sends a signal when both input signals are at high level to open the switch 20, during which time the output signal of the differential amplifier 19 is passed. Incidentally, a trigger pulse is also sent to the switch 20, and a transmission signal during transmission is removed to prevent malfunction.

Reference numeral 24 includes a level comparison circuit, etc., and detects the peak time of the output signal of the switch 20. Reference numeral 25 indicates a certain form based on the output signal of the peak detection circuit 24.
An example is a display signal forming circuit that uses a multivibrator to form a continuous display signal. This display signal is led to the display scanning circuit 9, and displayed together with the video signal on the display 10, for example, as a dotted straight line in the azimuth direction.

Note that signals from other ships' radars are often obtained from outside the detection range of the own ship's radar (in the case of own ship's radar, radio waves are received by going back and forth), and the radar detection distance is 1nl.
The existence of other ships outside I can be known more quickly. In this case, the switch 20 is opened only during the pause period (the period from the end of the signal display period until the next transmission).

Further, the present invention can also be applied to a radar in which a detection signal is once written into a memory, and then read out repeatedly at high speed and displayed as a raster. In this case, the display signal formed at the time of peak detection may be written into the memory together with the received signal, for example, at the immediately subsequent transmission timing.

Further, in this embodiment, logarithmic amplifiers 17, 18 and differential amplifiers 19 are used for convenience, but the configuration is not limited to this, and as a result, a signal corresponding to kfA(t) can be extracted in order to determine the peak direction. It would be good if it were done.

(Effects of the Invention) As explained above, according to the present invention, the presence of other ships can be displayed as a signal on the radar display screen at the same time, so detection performance can be substantially improved. It is also possible to know the direction of its existence.

Furthermore, even if the own ship's transmitting means is out of order, the present invention can sufficiently achieve its function and reduce the risk by half.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of the present invention. FIG. 2 is a diagram for explaining the present invention in detail. FIG. 3 is a waveform diagram.

Claims (2)

[Claims] (1) A radar mounted on the own ship whose detection signal is displayed on the display in relation to the detection direction, an omnidirectional antenna that receives radio waves from other ships' radars, and a signal received by the own ship's radar. a circuit for extracting a signal obtained by dividing the signal by a signal received by the omnidirectional antenna; a switch for passing the divided signal when both of the received signals are obtained; a circuit for detecting the peak time of the output of the switch; A radar device comprising a display signal forming circuit which forms a display signal based on the circuit output and is guided to the own ship radar side and displayed. (2) The division signal extraction circuit includes first and third logarithmic amplifiers to which signals received by the own ship's radar and signals received by the omnidirectional antenna are respectively guided, and outputs of the first and second logarithmic amplifiers. 2. The radar device according to claim 1, further comprising a differential amplifier that outputs a difference signal.