JP2930678B2 - Side-looking sonar - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a side-looking sonar for detecting underwater in a wide area from the side of a ship.

[Prior art]

As shown in FIG. 7, the side-looking sonar is a fan-shaped ultrasonic beam (for example, a fan-shaped angle of 60 °, a divergence angle of 1.degree. In the sailing direction) that spreads right and left from a transducer mounted on both sides of the ship.
6 ゜) is transmitted, and its echo is detected by the transmitter / receiver, so that the undulation of the seabed, changes in sediment, fish school, etc. are displayed in different shades or colors according to the detection level. FIG. 8 shows an example of the installation of the transmitter / receiver. Two receivers R ₁ and R ₂ are provided on both sides, respectively, and one receiver R ₂ is also used for transmitting. Hereinafter, a method of measuring the depth and horizontal distance of an underwater object using these transducers will be described with reference to FIG. R ₁ and R ₂ are receivers starboard side, the S and underwater objects. The distance between the two receivers R ₁ and R ₂ is D, the angle formed by the line connecting the two receivers R ₁ and R ₂ with respect to the vertical direction is α, and the two receivers R
_1, a line segment OS connecting the middle point of the R ₂ O and underwater objects S r, the midpoint O
H and d represent the horizontal and vertical distances of the underwater object S with respect to, and the angle formed by the direction perpendicular to the line connecting the two receivers R ₁ and R ₂ and the line segment OS is θ. Assuming that the difference in length between the line segment R ₁ -S and the line segment R ₂ -S is ΔY, If the wavelength of the sound wave used is λ, the phase difference φ is From equation (2), Assuming that the direction of the underwater object S from the midpoint 0 is θ _H , θ _H = α + θ (4) Assuming that the underwater sound velocity is c and the time that the sound wave reciprocates along the line segment OS is t, Therefore, d = r · sin θ _H (6) h = r · cos θ _H (7) can be obtained. It should be noted that t is the time for reciprocating in R ₂ -S, but since it can be regarded as R ₂ -S ≒ OS, the line segment OS
Is the time to go back and forth. Thus, the echo from the same underwater object accompanying the beam transmitted by the receiver R ₂ is received by the two receivers R ₁ and R ₂ ,
By measuring the phase difference of the received signal at this time, that is, the distance difference, the direction of the underwater object with respect to the two receivers is obtained. On the other hand, the linear distance from the underwater object is obtained from the round trip time required by the sound wave, and therefore, based on these two measurement data, the depth d of the underwater object and the horizontal distance h from directly below the ship
Is determined.

[Problems to be solved by the invention]

In the above-mentioned conventional measuring apparatus, two sets of receiving systems of a receiver and a receiving circuit connected to them are provided for each shore, so that the phase characteristics are the same between the two sets of receiving systems. The exact phase difference cannot be determined unless adjusted
Due to aging, temperature change, and the like, a difference occurs in the phase characteristics between the receiver and the receiving circuit, and as a result, there has been a problem that the accurate direction of the underwater object cannot be measured. The present invention has been made in order to solve the above-described problem, and provides a side-looking sonar that eliminates a phase difference between two sets of receiving systems by using a reflected signal from the seabed immediately below the ship. The purpose is to:

[Means for Solving the Problems]

The present invention includes a pair of first and second receivers provided at positions separated by a predetermined distance on a straight line forming a predetermined angle with respect to a vertical line. To form a wide and narrow beam in the horizontal direction, the echoes of the beam are captured by first and second receivers, and the first and second receivers are connected to the first and second receivers, respectively. The phase difference (φ ′) between the two received signals obtained from the receiving circuit is detected by the phase difference detecting means, and based on the detected echo signal and the phase difference (φ ′), the depth of the object to be detected and In the side-looking sonar for calculating and displaying the horizontal distance to the object to be detected, the phase difference detecting means detects a phase difference (φ ₀ ′) when an echo from the seabed directly below the ship is detected. Detection means and echoes from the seabed directly below the ship When received at the first and second receivers, the phase difference between the two no-received signal due to the difference of installation place of both receivers and (phi _0), geometry of the two receivers Phase difference calculating means (15) previously calculated from the spatial arrangement, and correcting means for correcting the phase difference (φ ') with the difference between the phase differences (φ ₀ ) and (φ ₀ '). Features.

[Action]

In Figure 6, for example, when the receivers R ₂ to transmit an ultrasonic beam, it echoes from initially obtained seabed are echoes from the ship just below the seabed. When reception of this echo at two receivers R _1, R _2, if the phase characteristics of the two receivers R _1, receiver circuit phase characteristics are the same for R ₂ is the same, both receivers The phase difference φ _{0 of the} echo detected by R ₁ and R ₂ is expressed by the following equation. Here, θ ₀ is an angle formed by a direction perpendicular to a line connecting both receivers to a vertical line. However, since the phase characteristics are actually different between the two sets of receiving systems, the detected phase difference is different from the phase difference φ ₀ obtained by the equation (8), and if the detected phase difference is φ ₀ ′, then (φ ₀ −φ ₀ ′)
Is a phase shift existing in the two receiving systems. on the other hand,
If the phase difference between the two received signals actually detected through the first and second receiving circuits with respect to the underwater object S is φ ′, the phase shift in the two sets of receiving systems is canceled by the following equation. A true phase difference φ is obtained. φ = φ ′ + (φ ₀ −φ ₀ ′) (9)

【Example】

FIG. 1 is a control block diagram showing one embodiment of the side-looking sonar of the present invention. FIG. 1 shows only a part for detecting a phase difference in two sets of receiving systems on the starboard side. The port side has the same configuration. R ₁ and R ₂ are receivers description, one of receivers R ₂ are the transmitting shared. 3 is a trigger pulse generator for generating a trigger pulse, and 4 is a trigger pulse generator 3
A transmission amplifier for supplying transmission power to the reception unit R ₂ by more of the trigger pulse. 5 and 6 are receivers R ₁ and R ₂
This is a receiving amplifier that amplifies the received signal detected in step (a). 7
Reference numerals 8 and 8 denote zero-crossing rising detectors which detect a point in time when the output signals from the receiving amplifiers 5 and 6 cross the zero point from negative to positive and output a pulse. Reference numeral 9 denotes a clock pulse circuit for generating a clock pulse. Reference numeral 10 denotes a counter. When a pulse from the zero-crossing rising detector 8 is input as a reset signal, the clock pulse from the clock pulse circuit 9 is counted from 0. I do. Reference numeral 11 denotes a latch circuit, which latches the count value of the counter 10 as a phase difference φ 'when a pulse from the zero-cross rising detector 7 is input as a set signal. Reference numeral 12 denotes a comparator which determines whether or not the output signal is due to an echo from the seabed immediately below, based on whether or not the level of the output signal of the receiving amplifier 6 exceeds a predetermined value, and outputs a pulse when the output signal exceeds the predetermined value. . Reference numeral 13 denotes a flip-flop circuit, which is reset to “0” by a trigger pulse from the trigger pulse generator 3,
Next, when the pulse from the comparator 12 is input, "1"
Is set to Reference numeral 14 denotes a latch circuit. When a signal from “0” to “1” is input as a set signal from the flip-flop 13, a phase difference (referred to as φ0 ′) latched by the latch circuit 11 at this time. Latch. 15 is a calculator for calculating a phase difference phi ₂ based on the above equation (8). This phase difference φ ₀ is a phase shift between the two echoes from the seabed immediately below, and this phase shift is caused by the receiver
This is due to the mounting positions of R ₁ and R ₂ . A subtractor 16 subtracts the phase difference φ ₀ ′ latched by the latch circuit 14 from the phase difference φ ₀ calculated by the calculator 15. 17
Is an adder, and the phase difference φ ′ latched by the latch circuit 11 is added to the phase difference (φ ₀ −
φ ₀ ′) and the phase difference φ of φ ′ + (φ ₀ −φ ₀ ′)
Is output. The operation of the control circuit having the above configuration will be described with reference to the time chart of FIG. When the trigger pulse is outputted from the trigger pulse generator 3 for transmission, while being reset to flip-flop 13 is "0", the ultrasonic signal from the transmitter amplifier 4 is output, the more receivers R ₂ 4 As shown in the figure, an ultrasonic beam spreading in a fan shape to the starboard side is transmitted. When the depth of just below the ship and d, first echo from underwater objects within a radius d around the ship is detected by the wave receiver R _2, receivers at a next short time difference R It is detected at ₁ (the order of reception may be reversed for echoes from the horizontal direction), then echoes from the sea floor directly below the ship are detected by the receiver R ₂ ,
It is detected by the wave receiver R ₁ at a next slightly different times. FIG. 2 shows detection signals of both the receiving amplifiers 5 and 6 when detecting an echo from an underwater object. The output signal of the receiving amplifier 6 is applied to a zero-crossing rising detector 8.
Is the time t ₁ when crossed exactly the zero level from the negative pulse is detected is outputted by. When this pulse is supplied to the counter 10 as a reset signal, the counter 10
10 is cleared and the clock pulse output from the clock pulse circuit 9 is counted, and the count value is sequentially input to the latch circuit 11. On the other hand, for the output signal of the receiving amplifier 5, it is detected time t ₂ when crossed exactly the zero level from the negative by the zero-cross rising detector 7 outputs a pulse, the latch circuit the pulse as a set signal When supplied to 11, the latch circuit 11 latches the input count value. Thus the latch circuit 11 will latch the number of clock pulses between the time t ₁ to time t _2. The number of pulses is a time difference resulting from a difference in phase characteristics between the two receivers R ₁ and R ₂ and a phase characteristic between the two receiving systems. If the period is set to 1/360, the time difference is represented by the above-mentioned phase difference φ '. At the subsequent time points t ₃ and t ₄ , a zero-cross is detected for the echo from the sea floor, and the number of clock pulses counted during this time is latched by the latch circuit 11. Further, the output signal of the receiving amplifier 6 is compared by a comparator 12 as to whether or not its level exceeds a predetermined value. After detecting an echo from an underwater object within the radius d, an echo having a higher level than the seabed immediately below the ship is detected. When large echo level is detected by the wave receiver R _2, the comparator 12 pulses is output from, because it is supplied to the flip-flop 13 as a set signal from the flip-flop 13 is "0" to "1" Set. As a result, the phase difference (referred to as φ ₀ ) latched by the latch circuit 14 and the latch circuit 11 is latched. Next, relatively high-level echoes from the seabed distant from immediately below the ship are sequentially detected, and at this time, the set signal is output from the comparator 12, but the flip-flop circuit 13 has already been set to "1". Latch circuit because it is left
14 does not work again. Therefore, in each transmission, the latch circuit 14 latches only the phase difference φ0 ′ when an echo from the seabed directly below the ship is detected. On the other hand, the latch circuit 11 continuously latches the phase difference φ 'irrespective of an echo whose level is lower than underwater or an echo whose level is higher than the sea floor. In the subtracter 16, the phase difference φ ₀ latched by the latch circuit 14 from the phase difference φ ₀ (this is the phase difference due to the mounting positions of the receivers R ₁ and R ₂ ) obtained in advance by the calculator 15.
_{0 '(which} includes a phase difference caused between both the receiving system other than the phase difference phi ₀₎ is subtracted, the phase shift between two receiving systems (phi ₀ -.phi _0') is determined, Latch circuit 11
Adder 17 to correct the phase difference φ '
Is obtained by adding φ ′ + (φ ₀ −φ ₀ ′) = φ
Is obtained. FIG. 3 is a block diagram showing another embodiment of the present invention. The difference from FIG. 1 is that, as shown in FIG. 4, a transmitter T for transmitting a beam Q having a narrow directivity angle toward the seabed directly below is provided separately on both sides. And a transmission amplifier 4 'for receiving the trigger pulse from the trigger pulse generator 3 and supplying the transmission power to the transmitter T. In operation, the beam Q is simultaneously transmitted toward the seabed by the transmitter T when transmitting from the receiver R ₂ ,
The two receivers R ₁ and R ₂ detect the echo from the direction directly below the seabed by the beam Q, and subsequently detect the echo by the ultrasonic beam transmitted by the receiver R ₂ . The phase difference φ ₀ ′ with respect to the echo from immediately below the seabed accompanying the transmission from the transmitter T is latched by the latch circuit 14, and the phase difference φ ₀ ′ with respect to the echo from the seabed with the transmission from the receiver R _2. Phase difference φ '
Are latched by the latch circuit 11, and the adder 17 obtains a true phase difference φ obtained by correcting the phase difference φ ′ by the phase difference deviation (φ ₀ −φ ₀ ′). Note that transmitters T need not be transmitting in each transmitting by receivers R _2, therefore, as shown in FIG. 5, transmitting at transmitting and another timing by the receivers R ₂ It is also possible to make the transmission possible by the device T, for which the trigger pulse generator 3 '
Has two output terminals 31 and 32, and the output terminal 31
Is connected to the transmission amplifier 4, and the other output terminal 32 is connected to the transmission amplifier 4 'and the flip-flop 13.
In this circuit configuration, the transmission timing between the transmitter T and the receiver R ₂ can be shifted, so that the echo from immediately below the seabed accompanying the transmission of the transmitter T and the echo from the receiver R ₂ This makes it possible to clearly distinguish echoes from the seafloor due to transmission.

【The invention's effect】

As described above, the present invention detects echoes from immediately below the ship using two receivers provided on one side, and detects the phase difference between the two signals detected at this time and the receiver The phase difference between the two receiving systems obtained from the difference from the phase difference obtained by calculation from the geometrical arrangement is obtained as correction data, and the phase difference between the two signals of the detected echo is corrected by the correction data. Therefore, the difference in the transfer characteristics between the receiver and the receiving circuit connected to the receiver is canceled out, thereby enabling accurate underwater exploration.

[Brief description of the drawings]

FIG. 1 is a control block diagram showing one embodiment of the side-looking sonar of the present invention, FIG. 2 is a time chart showing the operation of the control block diagram of FIG. 1, and FIG. FIG. 4 is a control block diagram showing an embodiment, FIG. 4 is a diagram showing an example of installation of the transducer in FIG. 3, FIG. 5 is a control block diagram showing still another embodiment of the present invention, and FIG. FIG. 7 is a view used to explain the principle of the present invention, FIG. 7 is a perspective view showing a beam formed by a side-looking sonar, FIG. 8 is a view showing an example of mounting a transducer, FIG. FIG. 4 is a diagram used to explain the operation principle of the side-looking sonar. R ₁ , R ₂ …… receiver, T …… transmitter, 3,3 ′ …… trigger pulse generator, 4 …… transmit amplifier, 5,6 …… receive amplifier, 7,8 …… zero crossing rise Detector 9 Clock pulse circuit 10 Counter 11 14 Latch circuit 12 Comparator 13 Flip-flop 15 Computing unit 16 Subtractor 17 17 Adder.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-72074 (JP, A) JP-A-63-196875 (JP, A) JP-A-4-357487 (JP, A) 73279 (JP, U) Actually open 1953-76854 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01S 7/52-7/64 G01S 15/00-15/96

Claims (2)

(57) [Claims] A pair of first and second receivers provided at a predetermined distance apart from each other on a straight line forming a predetermined angle with respect to a vertical line; Forming a wide beam in the direction and a narrow beam in the horizontal direction, capturing echoes of the beam with first and second receivers, and connecting the first and second receivers to the first and second receivers, respectively. The phase difference (φ ′) between the two reception signals obtained from the two reception circuits is detected by the phase difference detection means, and the depth of the object to be detected and the own ship are determined based on the detected echo signal and the phase difference (φ ′). A side-looking sonar that calculates and displays the horizontal distance from the object to the object to be detected, wherein the phase difference detecting means detects a phase difference (φ ₀ ′) when an echo from the seabed directly below the ship is detected. Deflection detection means and eco-friendly When reception of the first and second receivers, the phase difference between the two no-received signal due to the difference of installation place of both receivers (phi
₀ ) is calculated in advance from the geometrical arrangement of the two receivers, and the phase difference (φ ′) is the difference between the phase differences (φ ₀ ) and (φ ₀ ′). And a correcting means for correcting the side-looking sonar. 2. A phase shift detecting means for receiving, by a first and a second receiver, an echo from the seabed immediately below the ship obtained by transmitting from a separately provided transmitter. 2. The side-looking sonar according to claim 1, wherein a phase difference (φ ₀ ′) between the two received signals obtained from the first and second receiving circuits is detected at this time.