JPH044558B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention arranges a plurality of ultrasonic transducers on a circle or an arc, receives incoming waves arriving from the entire circumference direction or from a wide range of angular directions corresponding to the above-mentioned arc, and detects the incoming waves. The present invention relates to a detection device that displays information related to the source of an incoming signal, such as the distance or direction of the source of the incoming signal.

The present invention can be implemented in an underwater detection device that detects and displays schools of fish and underwater conditions, and a direction finder that detects and displays the direction of an incoming signal underwater.

Hereinafter, the case where the present invention is implemented in an underwater detection device will be explained.

A prior art device is described in US Pat. No. 3,846,745. This underwater detection device includes a plurality of transducers arranged at equal intervals on a circle, an interpolator that sends out interpolated reception signals, and a plurality of transducers each connected to the transducer via the interpolator. It consists of a beamformer made up of delay elements, a switch that connects each transducer to an interpolator, and a display that displays the output signal of the beamformer. The transducer groups are sequentially selected by the switch, and the incoming signals captured by the selected transducers are transmitted to the beamformer, so that received beams are sequentially formed in the center angle direction.
However, this conventional device requires many switches to sequentially select a predetermined group of transducers, which complicates the connection between the switches and the transducers, and also generates noise during switching operations. It had drawbacks.

The purpose of the invention is to provide a detection device based on a novel idea. Another object is to provide a miniaturized underwater detection device by significantly reducing the number of switches. Another object is to provide an underwater detection device that does not generate switching noise.

A detection device according to the present invention that receives signals arriving from a wide range of directions and displays information related to the arriving signals on a display means includes a receiving means that receives the arriving signals and their frequencies so that they change based on the Doppler effect; A matched filter that pulse-compresses the output signal of the receiving means, a display means that displays the output signal of the matched filter, and control that controls the receiving means and the display means so that they are related to each other. It consists of means.

Hereinafter, the principle of forming a receiving beam by an underwater detection device embodying the present invention will be explained.

A frequency modulated signal whose frequency changes linearly by kT within period T is expressed by the following equation.

f(t)=e ^{j(w0t-1/2kt2)} ...(1) where k=2πB/T B: Frequency change range In underwater detection equipment, the signal expressed by equation (1) above is approximately This is obtained by the above-mentioned wave receiving means which receives the incoming wave so that its frequency changes based on the Doppler effect. The signal expressed by the above equation (1) is supplied to a matted filter having an impulse response expressed by the following equation. h _(t) = e ^{j(w0t+1/2kt2)} ...(2) Output of the matted filter is expressed by the following formula.

g(t)=f _(t) ○*h _(t) =∫ ^∞ _{-∞ (t)}・h(τ-t)dt =∫t+T/2/t-T/2e ^{j(w0t-1/2kt2)}・e ^j { ^w
0( 〓 ^-t)2 } _dt ＝e ^{j(w0t-1/2kt2)} ∫〓 ^+1/2 〓 _-1/2 e ^-jk 〓 ^t dt ＝sinkτ／2T／kτ／2e ^{j(w0t-1/ 2kt2)} ...(3) This equation (3) shows that the amplitude of the output signal of the above matched filter is maximum when τ = 0, and the width T of the input signal is compressed to the pulse width 1/B. . In other words, a receiving beam is formed by the underwater detection device.

FIG. 1 shows a block diagram of one embodiment of the invention.

FIG. 2 shows a detailed view of FIG.

FIG. 3 shows an explanatory diagram of the wave receiving means used in the embodiment shown in FIG.

FIG. 4 shows a diagram for explaining the operation of the wave receiving means shown in FIG. 2.

Throughout the figures, the same reference numerals refer to the same parts.

In FIG. 1, the wave receiving means 1 is composed of, for example, an ultrasonic transducer 6 rotating at a constant speed, as shown in FIG. 3, and the signals captured thereby are sent to the matched filter 2. A vibrator 6 having a directivity characteristic with a half-reduction angle of 70° is rotated around an axis 8 by a monitor 7. Motor 7 is controlled by controller 4. As shown in FIGS. 1 and 2, assuming that a signal source 9 that sends out a signal of a constant frequency is located above the vibrator 6, the vibrator 6 approaches the signal source as it rotates. Repeat the movement of facing directly and moving away again. Therefore, the frequency of the signal received by the transducer 6 changes based on the Doppler effect, and the transducer 6
When moving through a distance corresponding to 90°, the frequency changes linearly. That is, this frequency change is expressed by the above equation (1). Although the configuration of the matched filter 2 will be described in detail later, the matched filter 2 is configured to have an impulse response characteristic expressed by the above equation (2). As mentioned above, the matched filter 2 pulse-compresses the input signal supplied from the vibrator 6, and outputs this pulse-compressed output signal expressed by the above equation (3) to the display 3.
Send to. In other words, matt filter 2
supplies a reception signal corresponding to the reception beam to the display 3. The controller 4 is composed of an oscillator and a control signal generator that generates an output signal of the oscillator. This control signal is supplied to the wave receiving means 1 and the display 3 and drives both in synchronization with each other. When the vibrator 6 is further rotated, the receiving beams are sequentially formed in the center angle direction at high speed, and the input signals captured by the receiving beams are sequentially supplied to the display 3. The display 3 is composed of, for example, a cathode ray tube,
The display surface is scanned by the electron beam in synchronization with the formation of a receiving beam which is sequentially formed concentrically in the direction of the central angle, thus performing PPI display.

As the transducer 6 is rotated, receiving beams are sequentially formed at high speed, and the receiving signals captured by each beam are sent to the display 3, and as a result, the underwater surrounding situation is displayed on the display. PPI is displayed on the display screen of 3.

In FIG. 2, the wave receiving means 1 is an ultrasonic transducer
T ₁ , T ₂ , T ₃ ...T ₄₀ and switches SW ₁ , SW ₂ , SW ₃
...SW ₄₀ , switch selector 10, and multiplier 11,1
2, a signal generator 13, and an adder 14. The ultrasonic transducers T ₁ , T ₂ , T _{3 , .} . . T ₄₀ are arranged on a circle at equal intervals so as to constantly receive incoming signals. The received signals captured by the transducers T ₁ , T ₃ , T ₅ ...T ₃₉ are transmitted through the switches SW ₁ , SW ₃ , respectively.
It is sent to one input terminal of the multiplier 11 via SW ₅ . . . SW ₃₉ . On the other hand, the received signals captured by the transducers T ₂ , T ₄ , T ₆ ...T ₄₀ are transmitted to each switch.
The signals are sent to one input terminal of the multiplier 12 via SW ₂ , SW ₄ , SW ₆ . . . SW ₄₀ . Each switch is composed of a gate, and as shown in FIG. 4A, SW ₁ ,
SW ₂ , SW _{3 .} . . SW ₄₀ are driven in this order. switch
After SW ₁ is closed, when half the duration of the square wave has elapsed and the received signal captured by transducer T _{1 passes through switch SW 1 ,} switch SW ₂ is closed and the signal is detected by transducer T ₂ . The received signal passes through this switch. When the remaining half of the square wave duration has elapsed, switch SW ₁ is opened and switch SW ₃ is closed instead, passing the received signal from transducer T ₃ to multiplier 11. However, switch SW ₂ converts the received signal from transducer T ₂ into multiplier 1.
Continue to pass to 2. When a further half of the duration of the next square wave has elapsed, switch SW ₂ is opened;
Then, the switch SW ₄ corresponding to the transducer T ₄ is closed. Similarly, the transducers T ₅ , T ₆ , T _{7 . .} . T ₄₀ are sequentially switched, and the received signals captured by these transducers are sent to the multiplier 11 or 12.
Switch selector 10 generates a square wave based on the output signal of controller 20. The signal generator 13 is
4B and C based on the output signal of the controller 20.
As shown in FIG. 2, two triangular wave trains having a phase difference of 180 degrees are generated, and these signals are sent to the other input terminals of multipliers 11 and 12, respectively. The multiplier 11 multiplies the received signal from the oscillator with the parsicular number supplied to one input terminal by the triangular wave (FIG. 4B) supplied to the other input terminal to generate an interpolated signal. and supplies it to one input terminal of the adder 14. As is clear from Fig. 4, the oscillators T ₁ , T ₃ , T ₅ ...
Switches corresponding to T ₃₉ SW ₁ , SW ₃ , SW ₅ …SW ₃₉
The switching operation is performed when the amplitude of the triangular wave is zero. Therefore, no matter how large the amplitude of noise is generated and supplied to the multiplier 11 when the switch is switched, the multiplier 11 generates an output signal free of noise. Similarly, the multiplier 12 is
The received signal from the even-numbered vibrator is multiplied by the triangular wave (C in Figure 4) supplied to the other input terminal, and the resulting product signal, which does not include switching noise, is sent to the adder 14. Supply to other input terminals. The adder 14 adds the output signal of the multiplier 11 and the output signal of the multiplier 12 to obtain a signal substantially equal to the signal obtained by one vibrator rotating at a constant speed.
The interpolated signal expressed by equation (1) is sent to the matched filter 2. As easily understood,
Multipliers 11 and 12, signal generator 13 and adder 1
4 constitutes a smoothing means and sends out an interpolated signal.

The matched filter 2 having the impulse response characteristic expressed by the above equation (2) consists of an analog delay line 15, resistors r ₁ , r ₂ , r ₃ . . . rn, operational amplifiers 16, 17, 18, and a resistor R ₁ , R ₂ , R ₃ ,
It is composed of R ₄ , R ₅ , and R ₆ . The analog delay line 15 is, for example, an easy-to-use
It consists of a Reteicon TAD-32 with equally spaced output terminals. One input terminal of the delay line 15 is supplied with a received signal from the wave receiving means 1, and the other input terminal is supplied with a clock pulse generated by the controller 20. The output signal of the receiving means 1 is transferred within the delay line every time a clock pulse is supplied. Daylay line 15
Inside, received signals arriving from different directions with a central angle of 90°, for example, are stored from the right end to the left end, and thus the received signals appear at each output terminal. The output signal appearing at the output terminal of the delay line 15 is weighted by resistors r ₁ , r ₂ , r ₃ . The other input terminals of operational amplifiers 16 and 17 are grounded. Resistors R ₁ and R ₂ are connected between the input and output terminals of operational amplifiers 16 and 17, respectively. Operational amplifiers 16 and 17
The output terminals of are connected to the input terminals of operational amplifier 18 through resistors R ₅ and R ₆ , respectively. resistance
R ₃ is connected between one input terminal and the output terminal of operational amplifier 18. A resistor _R4 is connected between the other input terminal and ground. The input terminal of the operational amplifier 16 is supplied with a signal obtained by sampling the positive polarity portion of the frequency-modulated received signal supplied to the analog delay line 15 . Assuming that the voltage values appearing at the output terminals of the analog delay line 15 are respectively represented by V ₁ , V ₂ , V ₃ . . . Vn, the output Ea of the operational amplifier 16 is given by the following equation.

Ea=(V ₁ /r ₁ +V ₂ /r ₂ +V ₃ /r ₃ +V ₄ /r ₄ +...+Vn/
rn) R ₁ Meanwhile, a signal obtained by sampling the negative polarity portion of the received signal supplied to the analog delay line 15 is supplied to the input terminal of the operational amplifier 17. The output Eb of the operational amplifier 17 is given by the following equation.

Eb=-(V ₅ /r ₅ +V ₆ /r ₆ +V ₇ /r ₇ +V ₈ /r ₈ +...Vn-4
/rn-4) The output Ec of the _R2 operational amplifier 18 is expressed by the following equation.

Ec=Ea−Eb=(V ₁ /r ₁ +V ₂ /r ₂ +V ₃ /r ₃ +V ₄ /r ₄ +……+Vn/rn)R ₁ +(V ₅ /r ₅ +V ₆ /r ₆ +V ₇ /r ₇ +V ₈ /r ₈ +...Vn-4/rn-4) R ₂ resistance r ₁ , r ₂ , r ₃ ...rn each resistance value is such that one impulse moves inside the delay line 15 through the oscillator. so that a waveform similar to the signal obtained by reversing the traveling direction of the frequency-shifted waveform signal stored in the delay line when transferred at the same speed as the switching is obtained at the output terminal of the operational amplifier 18. can be decided. That is, a matched filter having an impulse response characteristic expressed by the above formula (2) was obtained. Assuming that the signal source is located in the 0° direction with respect to the receiving transducer, and that signals arriving from a wide range of 90° directions ranging from -45° to +45° are stored in the delay line 15, The amplitude of the output signal of the operational amplifier 18 becomes maximum. If the signal source is located in a direction other than 0°, the operational amplifier 18
The output signal value of is very small compared to the signal value obtained when the signal source is located in the 0° direction. That is, the output signal of the operational amplifier 18 is mainly at 0°
This means that a received beam is formed in that direction. The output signal of the matched filter 2 is amplified and detected by an amplifier 21 and then sent to a brightness control terminal of a display 22. The polarized wave generator 23 generates a polarized wave that controls the electron beam of the cathode ray tube so that the electron beam concentrically scans the display surface of the cathode ray tube based on the output signal of the controller 20.

The transducer changes to T ₁ , T ₂ , T ₃ ...T ₄₀ ,
When switched sequentially in the order of T ₁ , T ₂ , T ₃ ...T ₄₀ ,
An incoming signal from a signal source that generates a constant frequency signal is received such that the frequency of the received signal changes due to the Doppler effect, and is sequentially transferred within the analog delay line 15 to reach the rightmost storage element therein. be remembered. The signal source is the receiving means 1
If the signal source is located in the 0° direction relative to
Displayed in the 0° direction. The oscillator is further switched,
A new signal is supplied to the delay line 15 and transferred, and the oldest stored signal is accordingly erased, so that no target is displayed in the 0° direction of the display surface of the display 22. If the signal source is located in the +45° direction with respect to the wave receiving means 1, and the received signal is stored in the analog delay line 15, it arrives from a direction within a 90° range from 0° to 90°. , the signal sources are displayed in the same direction on the display surface of the display.

As can be easily understood from the above explanation, when the transducers are sequentially switched in the order of T ₁ , T ₂ , T ₃ ...T ₄₀ ,
The received beams are formed almost continuously and sequentially in the central angular direction.

FIG. 5 shows a block diagram of a matched filter used in an embodiment of the invention.

The output signal sent from the wave receiving means 1 is supplied to an analog-digital converter (hereinafter referred to as "A-D converter") 50. The output signal of the A-D converter 50 is supplied to the memory 51. Memory device 51
sequentially stores signals arriving from the direction of the central angle of 90° of the wave receiving means 1. The storage device 51 is composed of a random access memory (RAM) or a shift register. The output signal of the memory 51 is supplied to one input terminal of the multiplier 52. The memory device 53 has the same number of memory elements as the memory device 51, and stores a predetermined weight value in each element. The output signal of memory 53 is supplied to the other input terminal of multiplier 52. The signals stored in the memories 51 and 53 are:
The multiplier 5 reads out the data in a predetermined order.
2 and are multiplied together. Multiplier 52
The output signals are sent to the accumulator 54 and sequentially added and accumulated. Accumulator 54
The output signal is sent to a display 22 via an amplifier 21.

The storage device 51 is controlled by the controller 55 and the A-
Write and read operations for the output signal of the D converter 50 are performed. A new received signal sent from the A-D converter 50 is written into the memory element in the memory 51 in which the oldest received signal is stored. The read operation from the storage device 51 is performed, for example, in order from the oldest signal to the newest signal. The wait signals stored in the memory 53 are controlled by the controller 55 and read out sequentially.

The transducer changes to T ₁ , T ₂ , T ₃ ...T ₄₀ ,
When switched in the order of T ₁ , T _{2 .} . . , an incoming signal from a signal source generating a constant frequency signal is received such that the frequency of the received signal changes due to the Doppler effect, Memory unit 5 through
1 sequentially. If the signal source is located at 0° with respect to the receiving means 1 and a signal arriving from a direction within a 90° range extending from -45° to +45° is stored in the memory 51, this signal source is displayed. displayed in the 0° direction on the display surface of the device 22.

A received wave signal arriving from a direction within a range of 90 degrees and stored in the memory 51 is read out, and this signal and a predetermined weight value read out from the memory 53 in synchronization with this readout operation are added to the multiplier 52. are sequentially multiplied and accumulated in the accumulator 54. In the case of the above example, the output signal of the accumulator 54 includes signals arriving only from approximately the 0° direction, and therefore a receiving beam is formed in the 0° direction. When the transducer is switched further, a new signal is written and stored in the storage element in which the oldest signal was stored in its place. As a result, no target object is displayed in the 0° direction of the display surface of the display device 22. If the signal source is located in the +45° direction with respect to the wave receiving means 1, and the received signal is stored in the memory 51, the signal is received from a direction within a 90° range from 0° to 90°. The sources are displayed in the same direction on the display surface of the display.

In the above embodiment, the vibrators are arranged on a circle at intervals of 9 degrees of central angle, but it is also possible to arrange them at narrower intervals, for example, every 2 to 3 degrees. In this case, the output signal of the changeover switch is
1, 12 and the adder 14, the signal is directly supplied to the A/D converter 50.

Note that the vibrators may be arranged on a circular arc.

Note that it is also possible to arrange the vibrators in a staggered manner on two mutually parallel circles drawn on a cylinder. In this case, the output signal of the vibrator placed on the first circle is supplied to the multiplier 11, and the output signal of the vibrator placed on the second circle is supplied to the multiplier 12. .

Note that in the above embodiment, the signal generator 13
Although a triangular wave is generated, a sine wave or a cosine wave may also be generated.

In the above embodiment, signals arriving from directions within a 90° range are stored in the memory 51, but signals arriving from directions within a larger or smaller angle range may also be stored.

Note that it is also possible to use a plasma display or a light emitting diode array instead of a cathode ray tube as a display device.

As described above, the present invention can provide a detection device that digitally pulse-compresses an incoming signal to be received and forms a received beam sequentially and substantially continuously in different directions as viewed from a receiver. can.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention. FIG. 2 is a detailed view of FIG. 1. FIG. 3 is an explanatory diagram of a wave receiving means used in the embodiment shown in FIG. 1. FIG. 4 is a diagram for explaining the operation of the wave receiving means shown in FIG. 2. FIG. 5 is a block diagram of a matched filter used in an embodiment of the invention.

Claims (1)

[Claims] 1. A detection device that sequentially forms a received beam in the horizontal direction underwater, receives incoming waves arriving from a wide range of directions with this received beam, and displays the arriving waves on a display, which includes: By arranging multiple ultrasonic transducers on the top at approximately equal intervals, selecting each transducer in the circumferential direction at the same speed, and extracting the incoming signal captured by each transducer, the Doppler effect is applied. A receiving means for receiving an incoming signal such that its frequency is shifted; an A-D converter for converting the output signal of the receiving means from analog to digital; and storing the output signal of the A-D converter. a first storage means for storing weights; a multiplier for multiplying the output signal of the first storage means by the weight output from the second storage means; a mated filter which pulse-compresses the output signal of the wave receiving means, and a display means which displays the output signal of the matched filter in relation to the direction of arrival; 1. A detection device comprising a control means for controlling a wave receiving means and a display means so that these means are operated in association with each other.