JPH01237482A - Radar-transponder apparatus for search and rescue - Google Patents

Abstract

PURPOSE:To obtain a radar-transponder apparatus having an echo emphasis function together, by providing a pulse train generator, a voltage squaring approximate characteristic integrating circuit, a gate/addition circuit and a fundamental pulse generator for transmission. CONSTITUTION:A radar-transponder apparatus is provided with a video amplifier 5, a one-twentieth frequency divider 9, a pulse delay circuit 19, a sawtooth wave generator 26, a microwave FM oscillator 28, etc. A pulse train generator 8a generates a pulse train of a prescribed pulse width, and a voltage squaring approximation characteristic integrating circuit 25 integrates the output pulse train of the pulse train generator 8a and outputs a slope waveform of squaring characteristic approximation. A gate/addition circuit 27 selects an output of the integrating circuit 25 during a period corresponding to a retrace time, while selecting a sawtooth wave during a period other than the retrace time, and it outputs a composite output as a frequency modulation signal to the FM oscillator 28. A fundamental pulse generator 10 for transmission is provided in connection with the frequency divider 9 in parallel therewith and through a selector switch, and it is started at every system trigger to generate a fundamental pulse for transmission having a pulse width corresponding to the retrace time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has an echo enhancement function and is installed in a small ship made of non-metallic materials such as FRP (reinforced plastic) or wood. This invention relates to search and rescue radar transponder equipment whose existence can be easily discovered.

[Conventional technology]

It is a well-known fact that in recent years, most ships are equipped with a 9 GHz band marine radar, which is used as an excellent navigational aid. This device is effective in times of heavy fog and at night when visibility is poor.

In particular, from the perspective of a ship equipped with a marine radar, islands, coasts, ships in transit, etc. are displayed as if viewing a map, making it extremely easy to determine the actions of the own ship.

However, a large number of small vessels such as those mentioned at the beginning are navigating around ports, narrow channels, and coastal areas.

It is also true that Japan is struggling with measures to prevent collisions with these ships.

The first reason for this is that non-metallic ships are difficult to see on radar, and the second is that ships, like cars, cannot be maneuvered as desired; It is no exaggeration to say that the ship coasts about 10 times more often than the ship's captain.

Therefore, early detection of these small vessels is essential for ships equipped with marine radar.

Therefore, some small vessels are equipped with radar reflectors (corner reflectors, Luneberg lenses, etc.) to facilitate the above-mentioned early detection, but the more effective the echo, the more effective it is. There are few with a large reflective area, and most have a side or diameter of up to about 30 an.

The reason for this is thought to be that the above-mentioned small ships do not have a place to install a large radar reflector, or even if they do, the top-heavy problem cannot be solved due to problems with wind pressure resistance and weight reduction.

On the other hand, in recent years, 9GHz
Compact search and rescue radars and transponders to be installed on ships, lifeboats, life rafts, etc. mounted on ships are being put into practical use, and Japan is already the first in the world to put them into practical use. Floating transponders have been approved as testing stations and some fishing boats are equipped with them.

This usefulness has been recognized by the IMO (International Maritime Organization), and it has already been recognized as IMOPerformance 5 standard.
(Resolution A, * * +k)M
SC53/24. Annex8 ・C0M31/WP
, 1. Annex 5 defines the performance requirements for the Survival Paper Radar Transponder (hereinafter referred to as 5ART).

Recommendation 62 of these CCIR (Consultative Committee on International Radiocommunications)
According to Article 8 [TECHNICAL CHARACTE]
RISTIC8FOR5EARCHAND RESC
Operational requirements are added to the main items of UE RADAR TRANSPONDER8).

In ANNEX 1 of CCIR Recommendation Article 628 above, M
INIMUM TECHNICAL CHARAC
TERISTIC8FOR... A frequency sweep signal is defined as [3, Sweeprate:
5 μs±1 μs, 4, Form of s
weep: sawtooth, fast: ret
urn<1μS]. That is, the frequency sweep waveform is a sawtooth wave with a retrace time of 1 μs or less, and a repetition time of 5 μs±1 μs.

This regulation stipulates the length and shape of the Xt reporting symbol, which will be described later, and the above-mentioned clause 41 is interpreted to have been taken into consideration so that the number of symbols concerned is not ambiguous.

Figure 5 shows 5AR, which corresponds to the standard of CCIR Recommendation Article 628.
This is a system diagram of a conventional search and rescue radar transponder device by T. In the figure, ] indicates a receiving antenna that receives and outputs radar radio waves of a pulse radar, and 2 indicates a 5A antenna.
RT response radio wave J.

3 is a microwave amplifier that amplifies the output of the receiving antenna 2, 4 is a microwave detector that detects the output of this microwave amplifier 3, and 5 is a microwave detector. This is a video amplifier that amplifies the video signal output from 4.

Reference numeral 6 denotes an operation stop circuit during transmission, which stops the operation of the microwave amplifier 3 based on the output of the pulse trailing edge extension circuit 12.

Reference numeral 7 denotes a transmitting/receiving switching circuit which performs a transmitting/receiving switching operation based on the output of the pulse trailing edge expansion circuit 12, and outputs the output to the comb-shaped pulse generator 8 at 5 μs intervals.

A 20 frequency divider 9 divides the output of the 5 μs interval comb-shaped pulse generator 8 by 20, and outputs the output to the pulse trailing edge expansion circuit 12, the low frequency power amplifier 13, and the pulse delay circuit 19. The output of the low frequency power amplifier 13 is output to an acoustic monitor 14 (loudspeaker) of the radar pulse repetition frequency.

15 is a solar light receiver/detector whose output is the illuminance discriminator 1
6 to detect it. Reference numeral 17 inputs the output of the illuminance discriminator 16, the output of the pulse trailing edge expansion circuit 12, and the output of the power switch (mercury or magnetic switch) 20, and outputs the output to the flashing marker lamp 18.

The power switch 20 uses a mercury switch if it is a floating type, or a reed switch if it is installed on a ship's life raft or lifeboat, and is opened and closed by a magnet 20a, and is powered by a lithium manganese dioxide battery. A voltage of 100 is applied.

The radar pulse repetition frequency acoustic monitor 14 and magnet 20a are used only for life rafts and lifeboats.

23 is a voltage stabilization circuit which inputs the output voltage of the manganese dioxide lithium battery 100 through the power switch 20 and supplies a stabilized voltage to each electronic circuit, and also applies the stabilized voltage to the electronic switch circuit 24. It is.

This electronic switch 24 inputs the output of the pulse delay circuit 19, performs switching, and outputs a microwave FM oscillator driving pulse.

26 is a sawtooth wave generator (with built-in pre-emphasis/temperature compensation circuit) which inputs the output of the 5μS interval comb pulse generator 8 and outputs a sawtooth wave frequency modulation signal with a period of 5μ and a repetition rate of 20. .

A microwave 28 is driven by the microwave FM oscillator drive pulse outputted from the electronic switch circuit 24, and generates a microwave FM signal by inputting the sawtooth frequency modulation signal outputted from the sawtooth wave generator 26. It is a wave FM oscillator. The output of this microwave FM oscillator 28 is transmitted from the transmitting antenna 1 to the radar-equipped ship by transmitting 5ART response radio waves J+.
k is emitted as a radio wave.

30 is a humidity detection circuit, 29 is a moisture absorption indicator light (red) that displays the output of this humidity detection circuit 30, and 31 is an operation indicator light (edge).

Next, the operation will be explained. FIG. 6 is a waveform diagram of each main part of FIG. 5, and the same symbols shown in FIGS. 5 and 6 indicate the same or equivalent parts.

Now, when the pulse radio wave a of the radar shown in Figure 6 (a) is emitted, it is delayed by the time corresponding to the relative distance to the target, attenuates as shown in Figure 6 (b), and reaches 5ART as a radar radio wave. do. This pulse radio wave a is emitted hundreds to thousands of times per second, but only two of these are shown in FIG. 6(a).

5ART receives the radar radio wave shown in FIG. 6(b) with the receiving antenna 2, regardless of the pulse width of the pulse radio wave a, passes through the microwave amplifier 3 and the microwave detector 4, and then outputs the video signal. The video signal is amplified by an amplifier 5, and a system trigger C is obtained at its output terminal with reference to its leading edge as shown in FIG. 6(c).

Since 5ART targets horizontally polarized waves such as ship radars, all antenna systems transmit and receive signals using the same polarized waves. Also, this directivity is omnidirectional in the horizontal plane, and 25 in the vertical plane.
Characteristics exceeding 100% are required.

In other words, this is determined because the 5ART itself or the life raft or lifeboat equipped with the 5ART needs to be always oriented even if it is exposed to waves.

There is no special tuning circuit in the 5ART receiving section, i.e., microwave amplifier 3, microwave detector 4, etc., until system trigger C is obtained, and the frequency range is approximately 9300-9500MHz.
It has an even broadband performance.

Therefore, if the reaching level of radar radio waves exceeds a certain value, all radar radio waves within this frequency band can be received.

Note that since there is a concern that there will be a time delay between receiving the radar radio wave and deriving the system trigger C mainly due to the frequency bandwidth of the video amplifier 5, one having wideband characteristics is also used.

System trigger C is the transmission/reception switching circuit 7 (2-man NAND,
(AND gate, etc.), and is added to a comb-shaped pulse generation circuit 8 for creating a time reference for frequency sweep.

The comb-shaped pulse d shown in FIG. 6(d) created here is 2
The frequency is divided by 20 by the 0 frequency divider 9 to create a basic pulse e for response transmission having a pulse width of 100 μs as shown in FIG. 6(e).

This value of 100 μs is constant and does not change even when irradiated with radar radio waves with different pulse repetition frequencies, and the upper limit is limited by this width, but if there are multiple radars in the same direction, from 110 μs onwards. Interrupts are possible until the next pulse.

Also, for one radar, approximately 8700pps
(Pulse repetition period: 115 μS or more) Compatible with radars with a pulse repetition period of 115 μS or more.

However, the pulse repetition frequency of the target radar is approximately 300-30, which is approximately equal to the audible frequency band of the voice band.
00 pps, and even if many radars are viewed from 5ART, the directions rarely coincide, and there is no synchronization relationship, so there is no practical problem.

In some types, this fundamental pulse e is also added to a low frequency power amplifier 13 to drive an acoustic monitor 14 (loudspeaker). This acoustic monitor 14 works effectively on things such as life rafts and lifeboats that are equipped with 5ART in advance and can be boarded by people in distress.

In other words, each time you are irradiated with a radar radio wave, you can tell the approach status of a ship or aircraft by the sound of a pulse repetition frequency (for example, if you are irradiated by two types of radar, the radar antenna rotates). As a result, two beeps and pings can be heard every few seconds, and at the same time, a response radio wave as described below is emitted).

In particular, if the tone is high, it means that the pulse repetition frequency is high, so it is likely that you are searching a short distance, and if the sound continues for a relatively long time, it may be due to side lobes or minor lobes other than the beam width of the radar antenna. Since it will also be illuminated by the enemy, it will show that it is in close range, and it will be a chance to launch a signal red flame. This information will also be useful in encouraging those in distress.

The basic pulse e for response transmission is slightly delayed by the pulse delay circuit 19, and the response transmission pulse g shown in FIG.
It is replaced by The reason for this is that the pulse trailing edge stretching circuit output f shown in FIG. 6(f) is output from the pulse trailing edge stretching circuit 12.
Figure 6 (j
) 5ART response radio wave j As can be seen from the time relationship, the time during which the response radio wave, ] is emitted, is connected to the loop with the receiving system by the output of the pulse trailing edge expansion circuit 12 (Fig. 6 (f)). This is to ensure timely interruption.

In addition, the first rise time corresponding to the retrace time of the frequency modulated signal shown in Fig. 6 (h) is expressed as the response radio wave J in Fig. 6 (j).
It is also used to prevent this, since unnecessary spectrum is likely to occur in addition to the occupied frequency bandwidth if it is included in the frequency band. This response transmission pulse g undergoes power conversion by an electronic switch 24 (high-speed switching transistor) and drives a microwave FM oscillator 28.

On the other hand, the comb-shaped pulse train d is generated by the sawtooth wave generator 26 to obtain the frequency modulation signal shown in FIG.

The microwave FM oscillator 28 is an electronically tuned oscillator that uses a micro-stripline as a resonant circuit, a varactor diode for frequency modulation, and a GaAs-FET as an oscillation element. As shown in the waveform of FIG. 6(h), the reason why the sawtooth waveform is non-linear is that the non-linear characteristic of the applied voltage vs. frequency change of the varactor diode is canceled and the frequency sweep is performed. This is due to the pre-emphasis circuit (pre-distortion) within the linearizing sawtooth wave generator 26.

FIGS. 6(k) and 6(1) show ideal frequency sweep patterns after applying this predistortion.

Thereafter, the transmitting antenna 1 emits a response radio wave J+ in all directions (this radio wave falls within a predetermined frequency range, i.e. 9
Response radio waves in the frequency range of 300-9500 MHz are emitted in each synchronized relationship. ).

When a radar captures this response radio wave, its video output m
appears as a pulse train as shown in FIG. 6(m), and the equivalent pulse width τe of this pulse is approximately as follows.

τe=B-t/△f...Equation (1),...B:
The passband width of a radar receiver in Hz, usually a maximum value of -3
Width t to dB drop point: Frequency sweep time per unit (seconds), this 5AR
5 μs for T Δf: Frequency sweep range Hz, 200 for this 5ART
MHz For example, if the passband width of the radar receiver is IOMH2,
The equivalent pulse width τe is 0.25 μs, and 20 bright spot rows are displayed every 5 μs (about 0.4 nautical miles) in the distance direction of PP1. In this case, the wider the passband width of the radar receiver, the more
The bright spot becomes larger and easier to spot.

Furthermore, as can be seen from FIG. 6(1), the time at which the video output m appears varies within a range of 5 μs depending on the operating frequency of the radar.

In other words, if we take 5ART as an example, which sweeps the frequency from high to low as shown in Figure 6, the higher the operating frequency of the radar, the smaller the distance error of the bright spot that appears at the beginning of the pulse train. On radar near 9300 MHz, it will appear approximately 0.4 nautical miles behind the distance at which 5ART exists.

Figure 7 shows 5AR reflected on PPI with an observation radius of 12 nautical miles.
A video photograph of T is shown. In this Figure 7, the left side is the Isegori coast, the right side is the Chita Peninsula coast, the bright part in the center is the location of the ship equipped with radar etc., and the bright spot line drawn diagonally from 4 nautical miles to about 12 nautical miles on the left is 5ART. This is a video captured by response radio waves.

The receiver passband width of this radar is 3MH7, and the image frequency described below is also received. These are installed in the microwave system of the radar receiver using an image rejection filter (or S
If an SB mixer (SB mixer) is not inserted, two waves can be received depending on the operating frequency, resulting in an image of 40 bright spot arrays instead of 20 bright spot arrays.

For example, if the radar transmission and reception frequency is 9375 MHz, the intermediate frequency is 30 MHz, and the local oscillation frequency is set to the higher side at 9405 MHz, the image frequency is 9435 MHz, which is 9375 MHz.
Bright spot rows for two waves of Hz and 9435 MHz appear alternately in the distance direction.

In any case, if such a large number of bright spot arrays are discovered, it means that a marine accident has occurred in that direction and rescue is required.

As the radar-equipped ship approaches its target, the PPI image of the array of bright spots spreads out in a fan shape as shown in Figure 8 for the same reason as mentioned in the acoustic monitor section, and when it reaches close range, it spreads out almost 360 degrees. It will appear on the entire circumference (SA
On the RT side, the sound will continue for a long time, or if it is a floating type, the flashing marker light will be lit almost continuously. ).

If this continues, the direction of 5ART will likely become unclear on the radar side, so if you narrow down the gain adjustment of the radar receiver and reconfirm the direction, 5ART should be discovered right in front of you.

The performance requirements for IM○ are that after the device has been activated for 4 consecutive days, the repetition frequency is 1. OOO
PPS radar is required to have the ability to transmit responses for 8 hours or more continuously, so a battery capable of responding to this requirement is used.

As the power switch 20, after a life is rescued, a reed switch is often used in the case of a lifeboat, and a mercury switch is often used in the case of a floating type. A mercury switch attempts to open and close by moving mercury particles around an electrode sealed in a container.

The floating flashing indicator light 18 is a flashing incandescent lamp that is placed inside a transparent lens and has a horizontal luminous intensity of approximately 1 candela.

In order to save power, during the day, sunlight is detected by a solar light receiving detector 15 and the blinking marker light 18 is turned on and off, and the blinking marker light 18 is automatically turned on and off at nightfall.

However, when radar radio waves are irradiated, the light interrupts according to the pulse regardless of whether it is day or night, and the light comes close to continuous lighting.

The container that encases these items is completely waterproof and also serves as a radome, but as a guide for periodic inspections, there is also a moisture absorption indicator light 29 that issues an alarm when the internal relative humidity detected by the humidity detection circuit 30 rises abnormally. We are prepared.

As mentioned above, 5ART takes advantage of radar's unique capabilities, such as extremely large transmission power, sharply directional antennas, and high receiving sensitivity, to create a simple system that can be used for search and rescue operations in the event of a maritime disaster. It is extremely effective as a rescue support device.

By the way, the CCIR recommendation Article 628 ANNEX 1-4
If the 0 term is revised as follows, the distance information will be reduced to one-fifth of the conventional value.
can be improved.

In other words, the frequency sweep signal is a sawtooth wave that starts at a time corresponding to the retrace time, and the retrace time is 1 μs ±
It is assumed to be 0.2 μs. 〕And it is sufficient.

Traditionally, the 5ART symbol has been designed to draw a row of about 20 bright spots in the distance direction on the radar PPI using a sawtooth wave frequency sweep signal that repeats every 5 μs during a transmission time of 1°O μS. Therefore, anything that occurs during the above retrace time has been interpreted as unnecessary.

As a result of actively reducing the retrace time of the 5ART, it is approximately 0.1 μs, and there is no fact that a bright spot in this time period is drawn on the radar even at close range, which will be described later.

Also, since the radar received at the above-mentioned image frequency may draw about 40 bright spot arrays, we dare to choose 201! ll
It is not necessary to be particular about the i-point sequence; rather, it has been found that the narrower the interval between each bright spot sequence, the greater its utility as distress information.

[Problem to be solved by the invention]

Since conventional search and rescue radar transponder devices are configured as described above, in 5ART, providing a unique symbol is the first priority, and distance information is considered to be secondary. Although there will be no practical inconvenience if this is done as is, it goes without saying that it is desirable for distance information to be as accurate as possible for search and ship maneuvering during the final rescue stage.

Also, if distance information can be accurately approximated on 5ART, by equipping it with an echo enhancement circuit, it will be possible to remove the radar reflector for echo enhancement as mentioned at the beginning. Furthermore, if it is equipped with a function that utilizes only the 5ART reception function, it will be useful as an approach warning for ships equipped with radar.

As described above, there were problems in that the accuracy of the distance information was poor, and the echo enhancement function and approach warning function for radar-equipped ships were lacking.

As an approximation technique, 85/ of the monthly magazine "Shipbuilding Technology"
11, Vol, 5ART on 18NnllP44-P51
There is a description of. Currently, the standards listed on pages 48 to 51 are approved as practical testing stations, but the applicable standards are determined by the CCIR interim meeting (ANNEX, 3, C0M2).
8/lNF2, DRAFT, RECOMMENDATI
○N AE/8, TECHNICAL CH
ARACTERISTIC8FOR5EARCHAND
RESCUE RADARTRANSPON
DER8 (Questions 28/ 8and4
5/8) THeCCIRl), especially before the effective receiving sensitivity and equivalent isotropic power were revised.

This invention was made to solve the above-mentioned problems, and makes it possible to improve the accuracy of distance information, facilitate the early detection of small vessels, and provide effective search and rescue support in the event of a maritime disaster.・Rescue radar: The purpose is to obtain transponder equipment.

In addition to the above objects, another invention of the present invention can avoid the complexity of periodic inspections, eliminate thinning of the positive electrode,
The purpose of the present invention is to obtain a radar transponder device for search and rescue that can be operated for a long time and can be expected to ensure reliability in the event of an emergency.

[Means to solve the problem]

The search and rescue radar transponder device according to the present invention includes a comb-shaped pulse generator that is activated by a system trigger obtained by receiving pulsed radar radio waves and generates a comb-shaped pulse, and a comb-shaped pulse generator that is activated by the comb-shaped pulse. A basic pulse generator for transmission generates basic pulses for transmission during echo enhancement corresponding to system triggers, and a basic pulse for response transmission that divides the frequency of the comb-shaped pulse to generate a basic pulse for response transmission with a pulse width wider than the reception pulse width. A frequency divider, a pulse delay circuit that delays the basic pulse for response transmission by a predetermined time in an emergency, and a basic pulse for transmission by a predetermined time in echo enhancement mode, and has voltage square approximation characteristics by integrating the comb-shaped pulse. an integrator circuit that obtains an integral output, a sawtooth wave generator that generates a sawtooth wave that is generated for each comb-shaped pulse, reaches a maximum within a time corresponding to the retrace time, and then falls for a while, and a plurality of sawtooth wave generators that generate an integral output. A gate/adder circuit deletes the comb-shaped pulses in the pulse width time of the wave and combines them with the output of the integrator circuit to output a frequency modulation signal, and a frequency modulation signal driven by the output of the pulse delay circuit produces FM. A microwave FM oscillator that modulates and outputs a response signal and an echo-enhanced response signal to the pulse radar is provided.

In addition, a search and rescue radar according to another invention of this invention
The transponder device includes a container that houses the search and rescue radar transponder device and has a hole for inflowing seawater at the bottom, a seawater battery that is housed in the bottom of the container, and a cradle provided at the bottom of the container. Usually, it is equipped with a power switch that allows the search and rescue radar 1 to be supplied with power from the ship to the lance bonder device.

[Operation] - In this invention, the comb-shaped pulse generator is activated by a system trigger, and each comb-shaped pulse is integrated by an integrating circuit so that it has a voltage squared characteristic, and the sawtooth wave is converted into a sawtooth wave. A frequency modulation signal is generated by generating a signal in a generator circuit, removing the pulse width of the comb-shaped pulse from the sawtooth wave by a gate/adding circuit, and adding the two, and dividing the comb-shaped pulse in a frequency divider. The pulse generator generates a basic pulse for response transmission with a pulse width wider than the pulse width of the received pulse, and also drives a basic pulse generator for transmission with a comb-shaped pulse to generate a basic pulse for transmission corresponding to the cycle of the system trigger. In an emergency, the basic pulse for response transmission output from the frequency divider is delayed by a pulse delay circuit for a predetermined period of time to drive a microwave FM oscillator, and after FM modulation with a frequency modulation signal, a response signal is sent to the pulse radar. It is emitted as a radio wave, and when in echo enhancement mode, the basic transmission pulse output from the basic transmission pulse generator is delayed by a pulse delay circuit, drives a microwave FM oscillator, and is FM modulated with a frequency modulation signal to enhance the echo. Emit a response radio wave.

In another aspect of the present invention, the container is installed at a predetermined location on a ship using a cradle, and a power switch is used to operate a search and rescue radar/transponder device using the ship's power to transmit response radio waves to the pulse radar. Launch, search,
When removing the rescue radar transponder device, the container is removed from the cradle and placed on the sea surface. When seawater enters the container and the seawater battery is immersed in the seawater, the seawater battery functions as a power source. The search and rescue radar 1 Lancebonder device enters echo enhancement mode and emits echo-enhanced response radio waves.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 1 to 7, 9.12 to 19°23.24, 2
6. 6.28 to 31 have the same expressions and operational functions as the corresponding parts of 5ART described in the explanation of FIG. 5, so the explanation will be omitted.

Furthermore, the * mark in Fig. 1 is a part that is automatically disconnected when functioning as a 5ART, and because the output impedance is low, short-circuit current can be ignored even if the electrode part comes into contact with seawater.

The part marked with ☆ is always connected but automatically shut off when functioning as 5ART, and can be controlled from outside the container using a reed switch and a magnet.

The part marked with ★ is the part that is always cut off, but is automatically connected when it functions as 5ART.This can be achieved by using a reed switch that operates in the opposite way to the above. 14 (hereinafter referred to as loudspeaker) onboard DC power supply 20 and power switch 21
remains).

8 is a comb-shaped pulse generator constructed using two monostable multivibrator ICs, one of which is used to set the pulse width [μS], and the other set to a pulse repetition period of 5 μs.

This pulse train is reset by the output of the 20 frequency divider 9, and the pulse width of the waveform e in FIG. 6(e) becomes 120 μs.

To set this to 100 μS, the above pulse repetition period should be set to 4
It may be set to μs. In addition, the above 1 μs pulse width is
In the case of 5ART shown in FIG. 6, the time was narrow "comb-like" of about 0.1 μs.

10 is a monostable multivibrator whose pulse width is the same as the above pulse width of 1 μs, and 11 is an operation mode selector switch.
A (proximity warning) cuts off transmission to the pulse delay circuit 19 and beyond, but at this time, echo enhancement radio waves and response radio waves are not emitted. When the selector switch 11 is turned to EE (echo emphasis), the output of the basic pulse generator 1o is sent out.

20 is an inboard DC power source such as a storage battery installed on the ship, 21 is a power switch, and 22 is a seawater battery exclusively used for 5ART, which is inactive because no seawater as an electrolyte flows in at all times. An example of the structure of this portion will be described later with reference to FIG. 4.

25 is an integrating circuit which is combined with a multiplier IC that introduces the pulse train d1 with a pulse width of 1 μs shown in FIG. 3(A) and derives a slow waveform approximating the voltage square characteristic at its output; FIG. 3(B) Obtain the waveform q.

27 inputs the pulse train dl, the waveform q, and the output r of the sawtooth wave generator shown in FIG.
This is a circuit with a gate and an addition function to obtain the waveform h1 as a frequency modulated signal shown in F).

That is, the waveform S in FIG. 3(D) is obtained by gating the waveform q with the pulse train d1. In the waveform U of FIG. 3(E), the first 1 μs portion of the output r of the sawtooth wave generator 26 is deleted by the pulse train d1.

Then, the waveform S and the waveform U are added to derive the waveform h1.

The reason for this is that in the conventional sawtooth wave generator 26, there is only one pre-emphasis circuit (predistortion), so that during the 1 μs period of waveform r in FIG. This is because the above-mentioned effects cannot be expected due to the shape of the product.

Figure 2 shows the system trigger C shown in Figure 2 (A) as a reference, the response radio wave at the time of echo emphasis in Figure 2 (G), jl, and the second wave of 2 and 5ART in Figure 2 (I). Figure (H), 2nd
The relationship between time and frequency from which the response radio waves j and kl in Figure (J) are derived is shown, but here the basic pulse e for response transmission of 5ART and the response transmission pulse g are described as being equivalent to those in Figure 6. is omitted. Also, the relationship between 5ARTs is
It is shown enlarged to contrast with the time relationship during echo enhancement.

By referring to the above functional explanation of the additional parts and the system diagram shown in FIG. 1, it will be easy to understand not only the proximity warning function but also the relationship between the echo enhancement operation and the 5ART function.

To add a supplementary explanation, the 5 μs interval comb-shaped pulse generator 8 always derives 20 pulse trains every time the system trigger C is generated, but the response radio wave during echo enhancement is as shown in Fig. 2 (C). Since it is regulated by the waveform e1 and the pulse g1 in FIG. 2(E), there is no interlayer, and this can be realized with a few additional functions as described above.

fl in FIG. 2(D) is the output of the pulse trailing edge expansion circuit 12 during echo enhancement, and hl in FIG. 2(F) is the frequency output from the gate/addition circuit 27 with a retrace time of 1 μS and a sweep period of 5 μS. The modulated signal, j in FIG. 2 (H), is a response radio wave of 5ART.

In addition, in the above embodiment, proximity warning, echo enhancement, and 5A
Although the functions of the RT are explained separately, it goes without saying that a proximity warning can be issued while the echo enhancement function is always activated, and if the configuration is changed in this way, the operation selector switch 11 in FIG. 1 can be omitted. It is simpler than the device configuration.

Figure 4 shows an example of an automatic release mechanism in an emergency when functioning as a 5ART, and shows an example of the important structure in Figure 1, which is a central cross-section of the cylindrical device viewed from the side of the lower part. It is a diagram. The left side shows an internal sectional view, and the right side shows only a part of it exposed. In the figure, 40 is a container of this device, the lower part of which houses a seawater battery 22, and that part of this container 40 has a A large number of seawater inflow holes 41 are provided. Although not shown, the surface of this seawater inflow hole 41 is covered with a water-soluble resin tape that dissolves after a while when crushed in seawater.

Reference numeral 42 denotes a pedestal for making the device stand up on its own, and is fixedly installed near the top of the bridge of the ship. Reference numeral 43 denotes an electrode that also serves as a waterproof plug. Taking the electrode shown in FIG. 1 as an example, three electrodes are required including the common line. Reference numeral 44 is a hole provided in the pedestal 42 for pushing up when the device is removed, which also serves as a water drain, and 45 is a waterproof backing, which normally prevents the seawater battery 22 from deteriorating due to rain, snow, seawater splashes, etc.

Reference numeral 46 denotes an electrode of the seawater battery 22, which is connected to the internal wiring 48 of the device via the seawater battery 22, etc. in order to connect to the low frequency power amplifier 13, marker light timer 17, and voltage stabilization circuit 23 shown in FIG. ing. The wire diameters of the electrodes 43, 46, electric wire 47, etc. are increased to prevent thinning due to seawater.

47 is an insulated wire provided on the ship side and connected to the loudspeaker 14 and power switch 21 shown in FIG.

49 is a plurality of the reed switches, and 50 is the magnet attached to the pedestal 42. Note that the operation mode changeover switch 11 in FIG. 1 is omitted in this figure.

In the example of FIG. 4, when the device is loaded onto the pedestal 42, it always operates in echo enhancement mode.

That is, since seawater does not flow into the seawater battery 22, the internal resistance is very high, and the seawater battery 22 is not affected in any way because it operates only with power from a storage battery or the like supplied from the ship.

In the event of an emergency such as a shipwreck, this device is removed from the pedestal 42 in order to function as a 5ART, and when it falls to the sea surface, the seawater battery 22 absorbs seawater and automatically starts operating.

The seawater battery compartment of the container 40 shown in FIG. 4 is represented by a cylinder with the same diameter, but if it is tapered from just below the part that contacts the waterproof backing 45 to the bottom, it will be easier to remove the battery. It is suggested that if the frictional resistance of the electrode 43, which also serves as a waterproof pillar, and the weight of this device are taken into account, an automatic detachment function in the event of a ship overturning can be realized.

As described above, the present invention is configured to have the following three functions.

(1) The acoustic display system is operated using only the reception function of 5ART, and is operated as an approach warning system for ships equipped with radar.

(2) The frequency sweep signal is a sawtooth wave that starts from the time corresponding to the retrace time, and the retrace time is 1 μs + 0
．． 2 μs] According to the revised proposal, the transmission time (pulse width) is set to only a chirp pulse of 1 μs±0.2 μs, and a moat is provided to provide one bright spot for echo enhancement.

(3) The frequency sweep signal is a sawtooth wave that starts from a time corresponding to the retrace time, and the retrace time is 1 μs ±
0.2 μs] A mode for the 5ART function will be provided in accordance with the revised proposal.

The above (1) allows a vessel equipped with the device of the present invention to monitor radar radio waves without emitting response radio waves, so it is possible to monitor the tone of the acoustic display, the connection time, the relationship between the relative distance to the approaching vessel, and the It is possible to understand the specific characteristics of the ship concerned, such as the location where this device is installed (the direction and height of the radio wave shadow, such as the mast, bridge, and chimney).

(2) above begins to occur from a close distance of about 1 nautical mile to the target vessel, where there is a risk of collision.
If you switch to this mote based on the progress of monitoring, it is possible to provide a bright spot on the target ship's radar PPI indicating the presence of your own ship.

In other words, 150m behind the ship as seen from the radar.
It becomes possible to display a bright spot within (0.08 nautical miles).

Now, when we consider how narrow the equivalent pulse width τe captured by the radar described in equation (1) above becomes, we find that the frequency sweep time t, which was originally 5 μs ± 1 μs, becomes 1 μs.
s±0.2 μs, resulting in a decrease of about 7 dB.

On the other hand, when the above t is about 5 μs ± 1 μs, the relative distance at which sufficient visibility can be obtained on a normal radar PPI is about 4 to 6 nautical miles, as shown in the example of the video photograph in Figure 7. Due to radio wave propagation characteristics, the loss will be canceled out as the distance approaches 2 to 2.5 nautical miles.

Furthermore, the target radar receiver passband width B is -3 dB.
Since it is effective up to the -7 dB point, which is a further 4 dB lower, the equivalent pulse width does not drop that much in a close range of about 2 nautical miles or less where the echo enhancement function is desired to be exhibited, and the echo enhancement ability remains.

The above (3) is a 5ART that also has the distance information mentioned above, and is not used unless an emergency situation such as a shipwreck occurs, but the 5A is rarely used like the conventional one.
Compared to RT, since it is in operation on a daily basis, it is easier to understand the operating status of the device, and self-inspection of the 5ART functions is also easier.

〔Effect of the invention〕

As described above, according to the present invention, in an emergency, the basic pulse for response transmission, which has a wider pulse width than the received pulse obtained by dividing the output of the comb-shaped pulse generator, is delayed for a predetermined time to drive the microwave FM oscillator. FM modulation is applied to the pulse radar using a frequency modulation signal obtained by adding the integrated output of the comb-shaped pulse and a sawtooth wave obtained by removing the pulse width of the comb-shaped pulse from the sawtooth wave synchronized with the comb-shaped pulse. A response radio wave is emitted, and when emphasizing an echo, it is driven by the output of a comb-shaped pulse generator to drive the transmission basic pulse generator in accordance with the system trigger cycle, and then the output basic transmission pulse is delayed by a predetermined time. Since the structure is configured to drive a microwave FM oscillator and emit an echo-enhanced response radio wave by applying FM modulation using the frequency modulation signal, early detection of the small vessel, which has been a problem in the past, can be easily carried out. Not only will it be possible, but in the unlikely event of a marine accident, 5=3
6 = There is an effect that allows the function as an ART to shine.

In addition, according to another invention of the present invention, a seawater battery is derived in which the electrode is sealed at all times and is activated by actively releasing the seal in an emergency, and the diameter of the positive electrode and electric wire that come into contact with seawater is increased. Since it is configured to extend the operating time,
Since the main parts are in constant operation, the hassle of inspections is eliminated, and reliability can be expected to be ensured in the event of an emergency.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a search and rescue radar transponder device according to an embodiment of the present invention, FIGS. 2 and 3 are waveform diagrams for explaining the operation of the main parts of FIG. 1, and FIG. The figure is a central sectional view showing the main structure of a search and rescue radar/transponder device equipped with an echo enhancement function according to the present invention, FIG. 5 is a system diagram of a conventional search and rescue radar/transponder device, and FIG. Figure 5 is a waveform diagram for explaining the operation of the main parts of the search and rescue radar/transponder device, and Figures 7 and 8 are target radars obtained from the search and rescue radar/transponder device in Figure 5. FIG. 2 is an explanatory diagram showing a PPI video photograph of . 5 is a video amplifier, 8 is a comb pulse generator, 9 is a 20 frequency divider, 10 is a basic pulse generator for transmission, 12 is a pulse trailing edge expansion circuit, 19 is a pulse delay circuit, 22 is a seawater battery,
25 is an integrating circuit, 26 is a sawtooth wave generator, 27 is a gate/summing circuit, 28 is a microwave FM oscillator, 4o is a container, 41 is a seawater inflow hole, 42 is a pedestal, 43 is an electrode, 49
is a reed switch (power switch). In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Patent applicant Mitsubishi Electric Corporation = 39- Engraving of drawings Figure 7 Procedural amendment (method) 1. Display of the incident Patent application No. 63-63698 2
Name of the invention Search and rescue radar/trasponder device 3 Representative of the person making the amendment Moriya Shiki 5 Date of amendment order June 28, 1988 7 Contents of the amendment Figures 7 and 8 as attached. to correct. (Engraving of drawings) Written amendment to the above procedure (voluntary)

Claims (2)

[Claims] (1) A video amplifier that generates a system trigger after receiving and detecting pulse radar radio waves, and a comb-shaped pulse generator that is activated for each system trigger and generates comb-shaped pulses to create a frequency sweep reference time. a frequency divider that divides the comb-shaped pulse to generate a basic pulse for response transmission with a pulse width wider than the received pulse width, and is driven by the output of the comb-shaped pulse generator and corresponds to the system trigger. a pulse delay circuit that delays the response transmission basic pulse for a predetermined time in an emergency and delays the transmission basic pulse for a predetermined time during echo enhancement, and the comb. a sawtooth wave generator that generates a sawtooth wave that is generated every pulse of the shape of the waveform and reaches a maximum within a time corresponding to the retrace time and then descends for a while;
an integrating circuit that integrates each of the comb-shaped pulses and outputs a slope waveform approximating the square-law characteristic; A gate/adder circuit that outputs a modulated frequency signal by adding and combining with the output, and a gate/adder circuit that is driven by the output of the pulse delay circuit and modulated by the frequency signal, and outputs an echo emphasis response radio wave to the pulse radar when the echo is emphasized. and a microwave FM oscillator that outputs response radio waves of the radar transponder in the event of an emergency;
A search and rescue radar transponder device comprising a pulse trailing edge expansion circuit that stops the operation of a receiving system when outputting the echo-enhanced response radio wave or the response radio wave of the radar transponder. (2) Contains a search and rescue radar transponder device, and houses a seawater battery that becomes a power source for the search and rescue radar transponder device using seawater when the search and rescue radar transponder device is removed from the ship and placed on the sea surface. and a container having a hole for the inflow of seawater, a pedestal provided at the bottom of the container for installing the search and rescue radar transponder device at a predetermined location on a ship, and waterproofing between the pedestal and the container. and a plurality of electrodes connected to the electrodes of the seawater battery and each part of the search and rescue radar transponder device, and provided in the container and when the seawater battery is not immersed in seawater, the search and rescue
Claim 1, characterized in that the search and rescue radar transponder device is equipped with a power switch for supplying power inside the ship to the search and rescue radar transponder device so that the search and rescue radar transponder device operates as an echo enhancement function. search and rescue radar transponder equipment.