JPH0718923B2 - Search and rescue radar transponder device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is equipped on a small ship made of non-metal such as FRP (reinforced plastic) or wooden structure, and its existence is easily found from a ship radar. As described above, the present invention relates to a search / rescue radar / transponder device having an echo enhancement function.

[Conventional technology]

In recent years, it is a well-known fact that most ships are equipped with 9 GHz band radar for ships and are used as excellent navigation aids. This device is effective when the fog is not good and at night.

In particular, from the viewpoint of a ship equipped with a radar for a ship, an island, a coast, a ship underway, etc. are imaged as they look at the map, so it is very easy to determine the action of the own ship.

However, the small boats mentioned at the beginning are very large in the vicinity of ports, narrow waterways, coasts, etc., and it is certain that they are struggling to prevent collisions with these vessels.

The first reason for this is that the above-mentioned non-metallic vessels are difficult to see on the radar, and the second is that the vessels cannot operate as if they were cars, and generally, even if the maximum stop command is given It's no exaggeration to say that you're going to coast about 10 times the length.

Therefore, early detection of these small vessels is indispensable for ships equipped with ship radar.

Therefore, there are some small vessels that are equipped with a radar reflector (corner reflector or Luneberg lens etc.) to compensate for the above-mentioned early detection, but it is effective enough to give an effective echo. There are few large reflective areas, and most of them have a side or diameter of up to about 30 cm.

It is considered that the reason for this is that there is no place to install a large radar reflector in the above-mentioned small vessels, or even if there is such a situation, the top heavy cannot be eliminated due to the problems of wind pressure resistance and weight reduction.

On the other hand, in recent years, targeting 9 GHz band radar mounted on ships and aircraft, small search and rescue radars equipped on ships and lifeboats and life rafts mounted on ships have been developed.
Transponders have been put to practical use, and Japan has already been the first in the world to accept floating transponders as a test station for practical use, and some fishing boats are equipped with them.

This usefulness has been recognized by the IMO (International Maritime Organization) and already
MO Performance standard (Resolution A. ***) MSC
53/24, Annex8 ・ COM31 / WP.1, Annex5
The performance requirements for transponders (hereinafter abbreviated as SART by quoting the initials below) have been resolved.

According to Article 628 of these CCIR (International Radiocommunication Advisory Committee) [TECHNICAL CHARACTERISTICS FOR SEARCH AND RES
CUE RADAR TRANSPONDERS] is added to the main requirements of operation.

In ANNEX 1 of Article 628 of CCIR Recommendation above, MINIMUM TECHNICAL
CHARACTERISTICS FOR ……. Frequency sweep signal is specified as [3.Sweeprate: 5μs ± 1μs.4.Form of swe
ep: sawtooth, fast return <1 μs]. That is, the frequency sweep waveform is a sawtooth wave having a sweep time of 1 μs or less, and the repetition time is set to 5 μs ± 1 μs.

This provision stipulates the length and shape of the symbols for distress notification, which will be described later, and it can be construed that item 4 above is considered so as not to obscure the number of such symbols.

FIG. 5 is a system diagram of a conventional search / rescue radar / transponder device by SART corresponding to the CCIR Recommendation 628 standard. In FIG. 5, 1 is a radar wave of a pulse radar b
Antenna for receiving and outputting, 2 is the response radio wave of SART
A transmitting antenna for outputting j and k to a radar-equipped ship, 3 is a microwave amplifier for amplifying the output of the receiving antenna 1, 4 is a microwave detector for detecting the output of the microwave amplifier 3, and 5 is microwave. This is a video amplifier that amplifies the video signal output from the detector 4.

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

Reference numeral 7 denotes a transmission / reception switching circuit that performs a transmission / reception switching operation by the output of the pulse trailing edge expansion circuit 12 and a comb-shaped pulse generator 8 at 5 μs intervals.
Is output to.

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

Reference numeral 15 is a sunlight receiving / detecting device, and its output is detected by an illuminance discriminator 16. 17 is the output of the illuminance discriminator 16,
Input the output of the pulse trailing edge expansion circuit 12 and the output of the power switch (mercury or magnetic switch) 20, and use the blinking indicator lamp 18
I am trying to output to.

The power switch 20 uses a mercury switch in the case of a floating type, and uses a reed switch in the case of equipping a life raft and a lifeboat, and is designed to be opened and closed by a magnet 20a. Is being applied.

The acoustic monitor 14 of the radar pulse repetition frequency and the magnet 20a are used only for liferafts and lifeboats.

Reference numeral 23 denotes a voltage stabilizing circuit, which inputs the output voltage of the manganese dioxide lithium battery 100 through the power switch 20 to supply the stabilizing voltage to each electronic circuit and also to apply the stabilizing voltage to the electronic switch circuit 24. Is.

The electronic switch 24 inputs the output of the pulse delay circuit 19 and performs switching to output a microwave FM oscillator drive pulse.

26 inputs the output of the comb-shaped pulse generator 8 at 5 μs intervals,
It is a sawtooth wave generator (pre-emphasis / temperature compensation circuit built-in) that outputs a sawtooth wave frequency modulation signal with a cycle of 5μ and a repeat count of 20.

28 is the microwave output from the electronic switch circuit 24
Driven by the FM oscillator drive pulse, the sawtooth wave generator 26
It is a microwave FM oscillator that receives a frequency-modulated sawtooth wave output from the device and generates a microwave FM signal. The output of the microwave FM oscillator 28 is radiated from the transmitting antenna 2 to the radar-equipped ship as SART response radio waves j, k.

Reference numeral 30 is a humidity detection circuit, 29 is a moisture absorption indicator (red) for displaying the output of the humidity detection circuit 30, and 31 is an operation indicator (green).
Is.

Next, the operation will be described. FIG. 6 is a waveform chart of each main part of FIG. 5, and the same reference numerals in the symbols shown in FIGS. 5 and 6 indicate the same or corresponding portions.

Now, when the radar pulse wave a shown in FIG. 6 (a) is emitted, it is delayed by the time of the relative distance to the target, attenuates as shown in FIG. 6 (b), and reaches the SART as radar wave b. To do. Although hundreds to thousands of pulsed radio waves a are emitted every second, only two of them are shown in FIG. 6 (a).

The SART receives the radar wave b shown in FIG. 6 (b) by the receiving antenna 1 regardless of the pulse width of the pulse wave a, passes through the microwave amplifier 3 and the microwave detector 4, and then the video signal is received. The signal is video-amplified by the amplifier 5, and a system trigger c is obtained at its output end with reference to its leading edge as shown in FIG. 6 (c).

Since SART targets horizontal polarization such as ship radar, all antennas transmit and receive with the same polarization. In addition, this directivity is required to be non-directional in the horizontal plane and 25 degrees or more in the vertical plane. That is, SART itself or SART
Life raft equipped with, lifeboat has been determined to always be directed even when exposed to the waves.

There is no special tuning circuit in the receiving part of the SART until the system trigger c is obtained, that is, the microwave amplifier 3, the microwave detector 4, etc., and it has a flat color band property from approximately 9300 to 9500 MHz.

Therefore, if the arrival level of the radar wave b exceeds a certain value, all the radar waves in this frequency band can be received.

Since there is a concern about a time delay mainly due to the frequency bandwidth of the video amplifier 5 from the reception of the radar radio wave b to the derivation of the system trigger c, a broadband characteristic is also used. The system trigger c passes through the transmission / reception switching circuit 7 (2-input NAND, AND gate, etc.) and is applied to the comb-shaped pulse generation circuit 8 for creating a time reference for frequency sweep.

The comb-shaped pulse d shown in FIG.
The frequency is divided by 20 by the frequency divider 9 and the pulse width 100 shown in FIG.
A basic pulse e for transmitting a μs response is created.

The value of 100 μs is constant, and does not change even if it is irradiated by radar radio waves with different pulse repetition frequencies. The upper limit is limited by this width, but if multiple radars exist in the same direction, from 110 μs onwards Interruption is possible before the next pulse.

Further, it is possible to deal with a radar of about 8700 pps (pulse repetition period of 115 μs or more) or less for one radar.

However, the pulse repetition frequency of the target radar is approximately 300 to 3000 pps, which is almost equal to the audio frequency band of the voice band.
There are few radars in the SART, and the azimuths do not coincide with each other even if many radars are viewed, and there is no synchronization relationship, so no practical inconvenience occurs.

There is also a type in which the response transmitting basic pulse e is added to the low frequency power amplifier 13 to drive the acoustic monitor 14 (loudspeaker). The acoustic monitor 14 effectively works for a liferaft or a lifeboat that can be boarded by a victim equipped with SART in advance.

That is, each time the radar radio wave b is irradiated, the approaching situation of the ship or aircraft can be known by the sound of the pulse repetition frequency (for example, when the radar antenna is radiated by two types of radars, the radar antenna rotates. Therefore, two sounds are heard every few seconds, and at the same time, a response electric wave as described later is emitted).

Especially if the sound is high, it means that the pulse repetition frequency is high, so it may be that you are searching for a short distance.If the sound continues for a relatively long time, side lobes other than the beam width of the radar antenna, minor lobes, etc. Since it is also being irradiated from, it is an opportunity to launch a signal red flame, indicating that you are in a close range. This information will also help encourage the victims.

The basic pulse e for response transmission is slightly delayed by the pulse delay circuit 19 and replaced with the pulse g for response transmission shown in FIG. 6 (g). The reason for this is that the pulse trailing edge stretching circuit output f of FIG. 6 (f) output from the pulse trailing edge stretching circuit 12 and that of FIG. 6 (j) radiated as a radio wave from the transmitting antenna 2 are shown.
As can be seen from the time relationship with the response radio wave j of the SART, the time when the response radio wave j is emitted is the pulse trailing edge expansion circuit 12
This is because the loop with the receiving system is surely cut off in time by the output of FIG. 6 (f).

In addition, the first rising time corresponding to the retrace time of the frequency-modulated signal h shown in FIG. 6 (h) is determined by the response radio wave j in FIG. 6 (j).
In addition, since it is easy to generate an unnecessary spectrum in addition to the occupied frequency bandwidth, it is also for preventing this. This response transmission pulse g is converted in electric power by the electronic switch 24 (transistor for high speed switch) and drives the microwave FM oscillator 28.

On the other hand, the comb-shaped pulse train d is generated by the sawtooth wave generator 26.
The frequency modulated signal h shown in FIG. 6H is obtained, and the microwave FM oscillator 28 performs simultaneous pulse / frequency modulation.

The microwave FM oscillator 28 is an electronic tuning oscillator that uses a micro strip line for a resonance circuit, uses a varactor diode for frequency modulation, and uses a GaAs-FET for an oscillation element. As shown by the waveform h in FIG. 6 (h),
The waveform of the sawtooth wave is made non-linear because the pre-emphasis circuit in the sawtooth wave generator 26 (preceding circuit) that cancels the non-linear characteristic of the applied voltage vs. frequency change of the varactor diode and linearizes the frequency sweep is used. Distortion).

FIGS. 6 (k) and 6 (l) show ideal frequency sweep patterns after the predistortion is applied. After that,
It is radiated from the transmitting antenna 2 as response radio waves j and k in all directions (this radio wave is irradiating with radar radio waves of any frequency, a predetermined frequency range, that is, 9300 to 9500 MHz.
The response radio waves in the frequency range are emitted in a synchronized relationship).

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

τe = B · t / Δf Equation (1) ∴B: Radar receiver passband Hz, which is usually the maximum value −
Width to 3dB drop point: Frequency sweep time (sec) per unit, 5μs in this SART Δf: Frequency sweep range Hz, 200MHz in this SART For example, if the passband width of the radar receiver is 10MHz, it is equivalent The pulse width τe is 0.25 μs and the PPI (Plane Position In
20 bright spot rows are displayed every 5 μs (about 0.4 nautical miles) in the direction of distance. In this case, the wider the pass band width of the radar receiver, the larger the bright spot and the easier it is to find.

Further, as can be seen from FIG. 6 (l), the time when the video output m appears changes within the range of 5 μs depending on the operating frequency of the radar.

That is, as shown in FIG. 6, taking SART in which the frequency is swept from the higher frequency to the lower frequency as an example, the higher the operating frequency of the radar, the less the distance error of the bright spot appearing at the beginning of the pulse train, On the radar near 9300MHz, it will be reflected about 0.4 nautical miles behind the SART distance.

Figure 7 shows a picture of the SART imaged on a PPI with an observation radius of 12 nautical miles. In Fig. 7, the left side is the coast of Ise Bay,
The right side is the coast of the Chita Peninsula, the shining part in the center is the position of the ship equipped with radar, etc. The bright point sequence drawn from about 4 nautical miles to about 12 nautical miles diagonally to the left is an image of SART response waves.

The receiver pass band width of this radar is 3 MHz, and the image frequency described later is also received. If the image removal filter (or SSB mixer) is not inserted in the microwave system of the radar receiver, these will be able to receive 2 waves depending on the operating frequency, and the image of 40 bright point sequence instead of 20 bright point sequence Is to become.

For example, the transmission / reception frequency of the radar is 9375MHz, the intermediate frequency is 30MHz, and the local oscillation frequency is set to the higher one.
If it is 5 MHz, the image frequency will be 9435 MHz, and the bright point strings for two waves of 9375 MHz and 9435 MHz will appear alternately in the distance direction.

In any case, if such a large number of bright spots are found, it means that a marine accident occurred in that direction and the rescue is requested.

As the radar-equipped ship approaches its target, the PPI image of multiple bright spots spreads out in a fan shape as shown in Fig. 8 for the same reason described in the acoustic monitor. It will appear all around (on the SART side, the sound continues for a long time, or in the case of the floating type, the blinking type indicator light is almost continuously lit).

As it is, the direction of the SART tends to be unknown on the radar side, so if you narrow down the gain adjustment of the radar receiver and reconfirm the direction, the SART should be discovered immediately in front of you.

According to the IMO performance requirements, it is 4 continuous after starting this device.
After continuous reception for a day, a radar with a repetitive frequency of 1000 pps is required to have a response transmission capacity of 8 hours or more in a row, so a battery having an ability to handle this is applied.

As the power switch 20, a reed switch is often used for liferafts and lifeboats, and a mercury switch is often used for a floating type. A mercury switch attempts to open and close an electrode enclosed in a container by moving mercury particles.

The floating blinking indicator light 18 is placed in a transparent lens and blinks an incandescent lamp having a horizontal plane luminosity of about 1 candela. In order to save power, the sunlight reception detector 15 detects sunlight in the daytime to turn off the blinking indicator lamp 18, and the blinking indicator lamp 18 is automatically blinked with the sunset.

However, when the radar radio wave b is emitted, it is interrupted according to the pulse regardless of whether it is day or night, and the continuous lighting is approached.

The container that wraps these is a completely waterproof type that also serves as a radome, but as a guideline for regular inspection, the moisture absorption indicator lamp 29 that issues an alarm when the relative humidity inside detected by the humidity detection circuit 30 rises abnormally I have it.

As anomalous, SART makes use of the peculiar performance of radar such as extremely large transmission power, sharp directional antenna, high receiving sensitivity, etc. It is a very effective rescue support device.

By the way, the distance information can be improved to one-fifth of the conventional one by revising the CCIR Recommendation Article 628, ANNEX1 item 4 as follows.

That is, the frequency sweep signal is a sawtooth wave that starts from a time corresponding to the retrace time, and the retrace time is 1 μm ±
0.2 μs].

Conventionally, the SART symbol is based on the principle that approximately 20 bright spots are drawn in the distance direction on the radar PPI by the frequency sweep signal of the sawtooth wave that repeats every 5 μs during the transmission time of 100 μs. , Those that occur during the above-mentioned blanking time have been interpreted as unnecessary.

As a result of positively reducing the SART retrace time, it is about 0.1 μs, and there is no fact that bright spots in this time zone are drawn on the radar even at a short distance described later.

In addition, the radar received at the above-mentioned image frequency has about
Since 40 bright spots may be drawn in some cases, it is not necessary to dare to stick to 20 bright spots, and it has become clear that the narrower the spacing between bright spots, the greater the effect as distress information.

[Problems to be Solved by the Invention]

Since the conventional search / rescue radar / transponder device is configured to be abnormal, in SART, giving a unique symbol is the first, and the distance information is considered as the secondary. Although this does not cause any practical inconvenience, it goes without saying that it is preferable that the distance information is accurate as much as possible for searching and maneuvering in the final rescue stage.

Also, if the distance information can be made accurate on the SART, by equipping it with a circuit with an echo enhancement function, it is possible to eliminate the need for a radar reflector for the echo enhancement described at the beginning. Having a function that utilizes only the reception function of SART will also be useful as an approach warning for radar-equipped ships.

As described above, there is a problem that the accuracy of the distance information is good and the echo enhancement function is lacking.

In addition, as an approximate technology, 85/11 of the monthly magazine "shipbuilding technology",
Vol.18, No.11, P44-P51 has SART description. Currently, the Practical Application Testing Bureau is approved as described in P48-P51, but the applicable standards are determined by the CCIR Intermediate Conference (ANNEX
3, COM28 / INF2, DRAFT, RECOMMENDATION AE / 8, TECHNIC
AL CHARACTERISTICS FOR SEARCH AND RESCUE RADAR TRA
NSPONDERS (Questions 28/8 and 45/8) THE CCIR), especially before the effective receiving sensitivity and equivalent isotropic radiated power are revised.

The present invention has been made to solve the above problems, and it is possible to improve the accuracy of distance information, facilitate early detection of small vessels, and eliminate the complexity of regular inspections. The purpose of the present invention is to obtain a radar transponder device.

[Means for Solving the Problems]

A radar / transponder device for search / rescue according to claim 1, wherein the comb-shaped pulse generator in the conventional device is replaced with a pulse train generator that generates a pulse train having a predetermined pulse width, and in addition, the pulse train generation is performed. Circuit that integrates the output pulse train of the detector and outputs a slope waveform that approximates the square characteristic, and selects the output of the integration circuit for the period corresponding to the retrace time, and generates the sawtooth wave during the period other than the retrace time. A gate / adder circuit that generates a combined output by selecting the output of the frequency divider and a frequency divider that generates a response transmission basic pulse in the conventional device, and the output is the output of the frequency divider. And a transmission basic pulse generator that is activated for each system trigger and that generates a transmission basic pulse having a pulse width corresponding to the blanking time. It is.

The radar / transponder device for search / rescue according to claim 2 is a radar / transponder device for search / rescue according to claim 1, in which a seawater battery is attached to a lower portion of a container of the device for radar / transponder for search / rescue. One electrode that also serves as a waterproof plug between a pedestal for installing and fixing the above-mentioned and that is in contact with the electrode is connected to a power source for a ship in parallel with the seawater battery.

[Work]

The search / rescue radar / transponder device according to the first aspect realizes the echo enhancement mode during normal navigation of a ship equipped with the device. That is, the microwaves emitted by the marine vessel radar mounted on other vessels are received, and the transmission basic pulse generator activated by each system trigger generated by the video amplifier generates the transmission basic pulse. The credit fundamental pulse passes through the pulse delay circuit and drives the microwave FM oscillator. Further, in order to obtain a frequency modulation signal input to this microwave FM oscillator, the pulse train generated by the pulse train generator activated for each system trigger is made into a slope waveform by an integrating circuit, and the same pulse train is made into a sawtooth wave generator. To form a sawtooth wave, and the slope waveform and the sawtooth wave are combined by a gate / adder circuit.
For a time corresponding to the pulse width of the basic pulse for transmission, a composite waveform that is a frequency-modulated signal is output by the microwave FM oscillator by outputting a response signal, thereby producing a bright spot on the radar PPI of the other ship. give.

On the other hand, it acts as a SART in an emergency such as a distress. That is, the microwave emitted by the search radar is received, the frequency divider activated for each system trigger generates a basic pulse for response transmission, and this basic pulse for response transmission passes through the pulse delay circuit and Drive the wave FM oscillator. Further, this microwave FM oscillator uses a frequency modulated signal as the gate / gate signal as in the echo enhancement mode.
The synthesized waveform synthesized by the adder circuit is input. The synthesized waveform, which is a frequency-modulated signal, is converted into the microwave FM for a time corresponding to the pulse width of the response transmission basic pulse.
The oscillator modulates and outputs a response signal, which gives a plurality of bright spots on the PPI of the radar receiver for searching.

Further, the search / rescue radar / transponder device according to claim 2 is connected to the power supply of the ship by the power switch in the echo enhancement mode, detached from the cradle in an emergency and floated on the sea surface, and seawater was stored in the container. Once in, the seawater battery starts working. At the same time, the output of the transmitting basic pulse generator is automatically cut off, and the output of the frequency divider is supplied to the pulse delay circuit.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, 1 to 7, 9, 12 to 19, 23, 24, 26, 28 to 31 are the same as the corresponding parts of the SART described in the explanation of FIG.

In addition, the mark * in Fig. 1 is a part that is automatically disconnected when it functions as a SART. Since the output impedance is low, the short circuit current can be ignored even if the electrode part comes into contact with seawater.

The part marked with ☆ is a part that is always connected but is automatically cut off when it functions as a SART.
It can be controlled by a magnet from outside the container.

The part marked with a ★ is a part that is always shut off, but is automatically connected when it functions as a SART. It can be realized by a reed switch that operates in reverse to the above. (When functioning as a SART, the sound monitor 14 ( Hereinafter referred to as loudspeaker)
DC power supply 110 and power switch 21 remain on board).

8a is a pulse train generator composed of two sets of monostable multivibrator ICs, one for setting the pulse width of 1 μs,
The other is 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 the figure (e) is 120 μs.

To set this to 100 μs, set the pulse repetition period to 4 μs.
It may be set to s. The 1 μs pulse width was a “comb shape” of about 0.1 μs in the SART shown in FIG.

Reference numeral 10 is a basic pulse generator for transmission composed of a monostable multivibrator whose pulse width is the same as the above-mentioned pulse width of 1 μs, and 11 is an operation mode changeover switch. In FIG. Although the transmission to the pulse delay circuit 19 and thereafter is cut off by the (approach alarm), at this time, the echo enhancement radio wave and the response radio wave are not emitted. When the changeover switch 11 is turned to EE (echo enhancement), the echo enhancement radio wave is transmitted according to the output of the transmission basic pulse generator 10.

110 is an inboard DC power supply such as a storage battery installed in the ship, 21 is a power switch, 22 is a seawater battery dedicated to SART, and it is inactive because seawater as an electrolyte does not always flow in. An example of the structure of this portion will be described later with reference to FIG.

25 is a pulse train d1 having a pulse width of 1 μs shown in FIG.
Is introduced, and a waveform q in FIG. 3 (B) is obtained by an integrating circuit combined with a multiplier IC for deriving a slope waveform of a voltage square characteristic approximation at its output.

27 receives the pulse train d1, the waveform q and the sawtooth wave generator output r of FIG. 3 (C), and outputs the output to FIG. 3 (F).
It is a circuit of a gate and an addition function for obtaining the waveform h1 as the frequency modulation signal shown in FIG.

That is, the waveform s of FIG.
Get by gated by d1. The waveform u in FIG. 3 (E) is the pulse train d1 for the first 1 μs portion of the output r of the sawtooth wave generator 26.
It has been deleted by. Then, the waveform s and the waveform u are added to derive the waveform h1.

This is because the conventional sawtooth wave generator 26 has only one pre-emphasis circuit (predistortion).
This is because during the 1 μs period of the waveform r in FIG. 3 (C), the waveform is in contrast to the waveform q, and the above effect cannot be expected.

In FIG. 2, the response radio wave j1 at the time of echo enhancement in FIG. 2 (G), k2 in FIG. 2 (I), and SART in FIG. 2 (based on the system trigger c shown in FIG. 2 (A) ( H) and the relationship between the time and frequency at which the response radio waves j and k1 in FIG. 2 (J) are derived are shown. Here, the basic pulse e for response transmission and the pulse g for response transmission of SART are shown in FIG. The description is omitted because it is equivalent to Also, the SART relationship is expanded and shown for comparison with the time relationship during echo enhancement.

Next, the operation will be described. First, the changeover switch 11 is NA
When the vehicle is leaning toward the (approach warning) side, neither the echo-emphasized radio wave nor the response radio wave is transmitted from the transmitting antenna 2 as described above. However, the output of the 20 frequency divider 9 output by the signal received by the receiving antenna 1 is applied to the low frequency power amplifier 13 to cause the loudspeaker 14 to ring. That is, in this case, the SART receiving function is used to obtain the approach information of another ship equipped with the ship radar.

When the changeover switch 11 is switched to the EE (echo enhancement) side after observing the passage of time from the start of ringing of the loudspeaker 14 described above, the output of the basic pulse generator for transmission 10 is supplied to the pulse delay circuit 19. Therefore, the search / rescue radar / transponder device starts operating in the echo enhancement mode.

In the echo enhancement mode, the signal received by the receiving antenna 1 causes the video amplifier 5 to generate a system trigger c, and the pulse train generator 8a outputs 20 pulse trains for each system trigger c. This pulse train has an integrating circuit 25, a sawtooth wave generator 26, and a gate / adding circuit 27.
Thus, 20 frequency modulated signals are generated for each system trigger c. On the other hand, since the output of the 20 frequency divider is cut off, the output waveform e1 of the transmission basic pulse generator 10 is supplied to the pulse delay circuit 19, and the pulse delay circuit 19 outputs the output waveform g1. Inside the microwave FM oscillator 28, this output waveform g1 acts as a gate signal, and as a result, from the transmitting antenna 2 through the microwave FM oscillator 28, j1 in FIG.
The response radio wave shown in is output.

In FIG. 2D, f1 is the output of the pulse trailing edge expansion circuit 12 in the echo enhancement mode, and h1 of FIG. 2F is the gate / addition circuit.
It is a frequency modulation signal output from 27 with a retrace time of 1 μs and a sweep period of 5 μs.

When operating as a SART in an emergency, the output of the basic pulse generator for transmission 10 is cut off and the output of the 20 frequency divider 9 is connected, so the output waveform of the 20 frequency divider 9 ((e) in FIG. 6). The same as the above, but the pulse width is 120 μs, is supplied to the pulse delay circuit 19, and the pulse delay circuit 19 outputs the output waveform (same as (g) in FIG. 6, but the pulse width is 120 μs). Inside the microwave FM oscillator 28, this output waveform acts as a gate signal, and as a result, the response radio wave indicated by j in FIG. 2 (H) is output from the transmitting antenna 2 via the microwave FM oscillator 28. It

It should be noted that in the above embodiment, the approach warning, the echo enhancement and the SART
Although it is explained separately for each function, it goes without saying that the proximity warning can always be made while the echo enhancement function is working.
If the configuration is changed in this way, the operation changeover switch 11 of FIG.
Can be omitted, the structure of the device can be simplified.

FIG. 4 shows an example of an automatic disengagement mechanism in an emergency when functioning as a SART, and is a central cross-sectional view of the lower part of the cylindrical device as seen from the side. The left side is an internal cross-sectional view, and the right side is shown with only part of it exposed.
Is the container of this device, the seawater battery 22 is stored in the lower part,
A large number of seawater inflow holes 41 are provided in that portion of the container 40. Although not shown, the surface of the seawater inflow hole 41 is covered with a water-soluble resin tape which melts after a while when immersed in seawater.

42 is a pedestal for making this device self-supporting, which is installed and fixed near the top of the bridge of the ship. Reference numeral 43 denotes an electrode which also serves as a waterproof plug, and when the electrode shown in FIG. 1 is taken as an example, three electrodes including the common line are required. 44 is a hole for pushing up when removing this device also serving as drainage provided in the cradle 42, 45 is a waterproof packing,
At all times, the seawater battery 22 is prevented from deterioration due to rain, snow, seawater splashes, and the like.

Reference numeral 46 denotes an electrode of the seawater battery 22, which is the low frequency power amplifier 1 shown in FIG.
3. The indicator lamp timer 17 and the voltage stabilizing circuit 23 are connected to the internal wiring 48 of the present device via the seawater battery 22 or the like. The electrodes 43 and 46, the electric wire 47, and the like have a large diameter to prevent thinning due to seawater. 47 is an insulated wire provided on the side of the ship, which is connected to the loudspeaker 14 and the power switch 21 of FIG.

49 is a plurality of the reed switches, and 50 is the magnet mounted on the pedestal 42. In this figure, the operation mode changeover switch 11 of FIG. 1 is omitted.

In the example shown in FIG. 4, when the present apparatus is loaded in the pedestal 42, the echo enhancement mode is always available. That is, since the seawater does not flow into the seawater battery 22, the internal resistance is very high, and the seawater battery 22 is not affected by the power supplied from the storage battery or the like supplied from the ship.

In the event of a ship release or an emergency in the event of an emergency, this device is detached from the cradle 42, and when it falls to the surface of the sea, the seawater battery 22 draws in seawater and automatically starts operating.

The seawater battery storage portion of the container 40 shown in FIG. 4 is represented by a cylinder having the same diameter, but if it is tapered from just below the portion in contact with the waterproof packing 45 to the bottom, it will be easier to remove. It is suggested that an automatic disengagement function at the time of rollover of a ship can be realized by taking into consideration the frictional resistance of the electrode 43 also serving as a waterproof column and the own weight of the present device.

As described above, the present invention is configured to have the following functions (2) and (3). Further, the function (1) can be realized by including the changeover switch 11, the low frequency power amplifier 13 and the loudspeaker 14 as described above.

(1) The acoustic display system (the changeover switch 11, the low frequency power amplifier 13 and the loudspeaker 14) is operated by using only the reception function of the SART to operate as an approach warning device for a radar-equipped ship.

(2) The frequency sweep signal is a sawtooth wave which is activated from the time corresponding to the above-mentioned blanking time, and the blanking time is 1 μs ± 0.
2 μs] In accordance with the revised proposal, the transmission time (pulse width) is limited to 1 μs ± 0.2 μs chirp pulse only, and a mode for providing one bright spot for echo enhancement is provided.

(3) The frequency sweep signal is a sawtooth wave that is activated from the time corresponding to the above-mentioned blanking time, and the blanking time is 1 μs ± 0.
2 μs] Provide a mode for the SART function according to the revised plan.

In the above (1), since the radar side can be monitored without emitting the response wave on the side of the ship on which the device of the present invention is mounted, the relation between the timbre of the acoustic display, the connection time, and the relative distance to the approaching ship, and It is possible to understand the characteristics peculiar to the ship concerned, such as the location where this device is installed (direction and height of the shadow of radio waves such as mast, bridge, chimney).

In (2) above, the relative distance from the target ship where a collision accident is a concern begins to occur from a close range of about 1 nautical mile, so
If the mode is switched to this mode in consideration of the monitoring progress of, the bright spot indicating the existence of the own ship can be given on the radar PPI of the target ship. That is, it is possible to display the bright spot within 150 m (0.08 nautical miles) behind the ship as seen from the radar.

Here, considering how narrow the equivalent pulse width τe captured by the radar described in the equation (1) of the conventional technique is, the frequency sweep time t was originally 5 μs ± 1 μs. Is 1 μs ± 0.2 μs, which is 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 is obtained on a normal radar PPI is about 4 to 6 nautical miles as in the example of the image photograph of FIG.
Due to the radio wave propagation characteristics, the loss of B will be offset if it approaches 2 to 2.5 nautical miles.

Furthermore, the target radar receiver pass band width B is effective up to the -7 dB point, which is 4 dB lower than the above -3 dB, so that at least the equivalent distance is required within the range of 2 nautical miles or less at which the echo enhancement function is desired. Does not decrease the pulse width,
Echo enhancement capability remains.

The above (3) is the SART that also has the distance information described in the section of the prior art, and is not used unless an emergency such as a distress occurs, but it is rarely used as in the past. Compared to SART, which does not have such features, it is in operation from day to day, so it has the advantages that it is easy to understand the operating status of the device, and that it is easy to perform self-inspection of the SART function.

〔The invention's effect〕

As described above, according to the present invention, the search / rescue radar / transponder device is provided with the pulse train generator and the transmission basic pulse generator, and in the normal sailing, the echo enhancement mode is set by the power supply in the ship. It operates and is configured to operate as a SART with a seawater battery in an emergency such as a distress, so it not only becomes a SART having distance information, but also has the same function as a radar reflector for echo enhancement,
Further, since the main parts of the search / rescue radar / transponder device can be operated at all times, the troublesomeness of the inspection is eliminated and the reliability can be expected in case of emergency.

Further, conventionally, an electrode to which a direct current voltage is applied has a kind of plating action when immersed in seawater, and the positive electrode may become thin and may eventually be broken. Since the diameters of the positive electrode and the electric wire to be touched are large, there is an effect that a search / rescue radar / transponder device can be obtained in which the function related to the operation time does not deteriorate.

[Brief description of drawings]

FIG. 1 is a system diagram of a search / rescue radar / transponder device according to an embodiment of the present invention, and FIGS. 2 and 3 are waveform diagrams for explaining the operation of each main part of FIG. 1, and FIG. FIG. 5 is a central sectional view showing the main structure of a search / rescue radar / transponder device equipped with an echo enhancement function of the present invention, FIG. 5 is a system diagram of a conventional search / rescue radar / transponder device, and FIG. 6 is Waveform diagrams for explaining the operation of each main part of the search / rescue radar / transponder device shown in FIG. 5, and FIGS. 7 and 8 are target radars obtained from the search / rescue radar / transponder device shown in FIG. It is an explanatory view showing a PPI video photograph of. 5 is a video amplifier, 8 is a comb pulse generator, 8a is a pulse train generator, 9 is a frequency divider by 20, 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 / adder circuit, 28 is a microwave FM oscillator, 40 is a container, 41 is a seawater inflow hole, 42 is a pedestal, 43 is Electrode, 49 is a reed switch (power switch). In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A video amplifier for generating a system trigger after receiving and detecting an electric wave of a pulse radar, and a comb-shaped pulse which is activated for each system trigger and generates a comb-shaped pulse train serving as a time reference for frequency sweeping. A generator, a frequency divider that divides the comb-shaped pulse train to generate a basic pulse for response transmission that has a pulse width wider than the received pulse width, and delays the output of this frequency divider for a predetermined time to transmit a response. A pulse delay circuit that generates a pulse, a sawtooth wave generator that generates a sawtooth wave that is generated for each pulse of the comb-shaped pulse train, reaches a maximum within the time of the pulse width of this pulse, and then temporarily drops, In the search / rescue radar transponder device, which is driven by the response transmission pulse and includes a microwave FM oscillator that frequency-modulates the sawtooth wave and outputs a response signal, the comb Equipped with a pulse train generator that generates a pulse train of a specified pulse width in place of the pulse generator, integrates the output pulse train of this pulse train generator, and outputs a slope waveform approximating the squared characteristic, and the retrace time. A gate / adder that selects the output of the integration circuit for a period of time to be output, and outputs a combined output obtained by selecting and combining the sawtooth wave as a frequency modulation signal to the microwave FM oscillator during a period other than the retrace time. A pulse width corresponding to the retrace time, which is provided in parallel with the circuit and the frequency divider, and the output of which is connected to the output of the frequency divider via a changeover switch. A search / rescue radar / transponder device comprising: a basic transmission pulse generator that generates a basic transmission pulse. 2. A power supply for the search / rescue radar / transponder device by seawater when the search / rescue radar / transponder device main body is housed and the search / rescue radar / transponder device is detached from the ship and put on the sea surface. A container containing a seawater battery and having a hole for inflowing seawater, a pedestal provided at the bottom of the container for installing the search / rescue radar / transponder device at a predetermined position on the vessel, A plurality of electrodes that also serve as waterproof between the base and the container and that are connected to the electrodes of the seawater battery and each part of the search / rescue radar / transponder device, and that are provided in the container and are immersed in the seawater battery If the radar / transponder device for search / rescue is operating as an echo enhancement function, the power supply in the ship is searched and rescued. Search and rescue radar transponder system as set forth in claim 1, wherein claims, characterized in that a power switch for supplying the radar transponder.