JPH04357487A - Side looking sonar - Google Patents

Abstract

PURPOSE:To measure the position of an object under water accurately by a method wherein a phase difference is determined at input points of two receivers with respect to a measuring point by calculation and a phase difference is measured with two receivers for the same measuring point to obtain a deviation of phase so that the phase difference measured is corrected by the deviation of phase. CONSTITUTION:When a trigger pulse from a trigger pulse generator 3 is inputted into a CPU21 through an input device 22, a measuring position of own ship and the bearing of navigation are read in form a highly accurate position measuring device 23 and a bearing measuring device 24 to determine an intersection with a contour line based on the value and a probing range inputted from a keyboard 25 beforehand. Distances are determined from the centers of receivers R1 and R2 to the sea surface below the intersection to obtain a phase difference phi'' corresponding thereto. A phase difference phi' is measured between two receivers for the same measuring point to obtain phi'-phi''=dphi as deviation of phase between the two receivers. The phase difference measured actually thereafter is corrected by the deviation dphi of phase to remove the deviation of phase difference generated between two receiving systems thereby measuring the position of an object under water accurately.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a side-looking sonar that detects underwater over a wide area to the side of a ship.

0002

[Prior Art] Side-looking sonar, as shown in Fig. 1, is a fan-shaped ultrasonic beam (e.g., fan-shaped angle of 60°, divergence angle of 1 in the navigation direction) that is spread from transducers installed on both sides of the ship. By transmitting a wave (.6°) and detecting the echo with the same transducer, the undulations of the sea floor, changes in bottom sediment, fish schools, etc. are displayed in shades or colors depending on the detection level.

FIG. 2 shows an example of how the transducer is installed. Two receivers R1 and R2 are provided on both sides, and one receiver R2 is used for both transmitting and transmitting waves. Below, a method for measuring the depth and horizontal distance of an underwater object using these transducers will be explained using FIG. 3.

R1 and R2 are starboard side receivers,
Let S be an underwater object. The distance between both receivers R1 and R2 is D
, α is the angle formed by the line connecting both receivers R1 and R2 with respect to the vertical direction, and r is the length of the line segment OS connecting the midpoint O of both receivers R1 and R2 and underwater object S. The horizontal and depth of the underwater object S with respect to point O are h and d, and the angle between the line segment OS and the direction perpendicular to the line connecting both receivers R1 and R2 is θ.

[0005] If the difference in length between line segment R1-S and line segment R2-S is ΔY, it can be regarded as ΔY=2・(D/2)・sinθ (1),
When the wavelength of the sound wave used is λ, the phase difference φ at ΔY is as follows: φ=360°·ΔY/λ =360°·D·sinθ/λ (2). (2
), from the formula, θ=sin-1 {φ・λ/(360°・D)} (3
) If the direction of the underwater object S seen from the midpoint O is θh, then θ
h=α+θ (4) is obtained.

[0006] If the underwater sound speed is c, and the time for the sound wave to travel back and forth along the line segment OS is t, then the straight line distance r is r=t・c/2 (5) Therefore, d=r・sinθh (6) h=r・cos θh (7) is obtained. Note that t is the time to travel back and forth along the line segment R2-S, but since it can be considered that R2-S≈OS, it was taken as the time to travel back and forth through the line segment R2-S.

In this way, the echoes from the same underwater object accompanying the beam transmitted by the receiver R2 are transmitted to the two receivers R1,
The direction of the underwater object with respect to the two receivers can be determined by receiving the wave at R2 and measuring the phase difference, that is, the distance difference, between the received signals at this time. On the other hand, since the straight line distance r to the underwater object S is determined from the round trip time required by the sound wave, the depth d of the underwater object and the horizontal distance h from directly below the own ship are determined from equations (6) and (7).

[0008]

[Problem to be Solved by the Invention] In the conventional measuring device described above, two sets of receiving systems, consisting of a receiver and a receiving circuit connected to these, are provided for each ship, so it is difficult to accurately measure the phase difference. In order to obtain this, it is necessary to make adjustments so that the phase characteristics of the two sets of receiving systems are the same, that is, the phase delays occurring in both receiving systems are equal, but due to aging, temperature changes, etc. If a difference occurs in phase characteristics between the receiver and the receiving circuit, and the measured phase difference includes a phase shift due to such a difference in phase characteristics, there is a problem that the accurate position of an underwater object cannot be measured. there were. The present invention has been made to solve the above-mentioned problems,
An object of the present invention is to provide a side-looking sonar that can accurately measure the position of an underwater object by correcting a phase shift that occurs between two sets of receiving systems.

[0009]

[Means for Solving the Problems] A side-looking sonar according to a first aspect of the invention includes a pair of first and second sonar devices located at a predetermined distance apart on a straight line forming a predetermined angle with respect to a vertical line.
a transmitting beam that is wide in the vertical direction and narrow in the horizontal direction from one of the receivers, and echoes of the beam are captured by the first and second receivers, A phase difference detection means detects the phase difference between both received signals obtained from the first and second receiving circuits connected to the first and second receivers, respectively, and detects the phase difference and the return of the echo. In a side-looking sonar that calculates and displays the depth of a detected object and the horizontal distance from the own ship to the detected object based on the time required, a depth information storage means for storing previously measured depth information of the seabed; The phase difference φ' detected by the phase difference detection means for an echo from a certain measurement point, the depth read from the depth information storage means for the same measurement point, and the measurement obtained by the positioning device. From the phase difference φ'' at the input point of the first and second receivers, which is determined by the horizontal distance of the own ship's position with respect to the point, the first receiver and receiving circuit, and the second receiver and a phase shift calculating means for calculating φ'-φ"=dφ as a phase shift occurring between the signals passing through both the receiving systems due to the difference in phase characteristics between the receiving circuit and the receiving circuit; detected by the phase difference detecting means during measurement. and correcting means for correcting the phase difference calculated by the phase shift calculating means using the phase shift dφ calculated by the phase shift calculating means.

A side-looking sonar according to a second aspect of the invention includes a pair of first and second receivers located at a predetermined distance apart on a straight line forming a predetermined angle with the vertical line;
A transmission beam that is wide vertically and narrow horizontally is formed from one of the receivers, and the echoes of said beam are
and a second wave receiver, and a phase difference detection means detects the phase difference between the received signals obtained from the first and second receiving circuits connected to the first and second wave receivers, respectively. In a side-looking sonar that detects and calculates and displays the depth of the detected object and the horizontal distance from the own ship to the detected object based on the phase difference and the time required for the echo to return,
A large number of pencil-shaped transmission and reception beams that partially overlap with the transmission and reception beams of the side-looking sonar are formed below and to the sides of the own ship, and the time required for the echoes to return and the detected object from the direction of each pencil beam are determined. a depth information input section that receives the depth and horizontal distance measured by a scanning sonar that calculates the depth and horizontal distance from the ship to the object to be detected; a phase difference at the input points of the first and second wave receivers, which is determined from the phase difference φ' detected by the means and the depth and horizontal distance to the same measurement target input to the depth information input section; φ', due to the difference in phase characteristics between the first receiver and receiving circuit and the second receiver and receiving circuit, the phase shift that occurs between the signals passing through both receiving systems is φ'- A phase shift calculation means for calculating φ"=dφ; and a correction means for correcting the phase difference detected by the phase difference detection means during measurement with the phase shift dφ calculated by the phase difference calculation means. It is characterized by:

[0011]

[Operation] In Fig. 4, even if the phase difference when an echo from a certain seabed point enters the receivers R1 and R2 is φ, the phase delay occurring in the receiver R1 and the receiving circuit S1 is dφ1. Assuming that the phase delay occurring in the transducer R2 and the receiving circuit S2 is dφ2, the phase difference φ' output from the phase difference detection circuit T is as follows: φ'=φ+(dφ1−dφ2) (8). dφ
1-dφ2=dφ is the phase shift occurring between the two receiving systems.

On the other hand, the depth information for each seabed point is read from a depth information storage means that stores the depth for each seabed point from a contour map, etc., and the own ship position is calculated using this depth and the own ship position output from the positioning device with respect to the measurement point. The phase difference φ'' at the input points of the first and second receivers is calculated based on the horizontal distance from If there is no phase shift, φ''=φ', but in reality there is a phase shift dφ between the two receiving systems, and this phase shift dφ is determined by the following equation. φ'−φ”=dφ (9)

If the phase difference shift dφ is known in this way, if the phase difference φ' detected by the phase difference detection means during measurement is corrected by the phase difference shift dφ by the correction means, the phase difference can be corrected by the phase difference shift dφ. The phase difference shift dφ included in φ' is removed.

[0014] The second invention uses accurate depth information obtained by scanning sonar in place of the above-mentioned previously measured seabed depth information. Here, the differences between side-looking sonar and scanning sonar will be explained. . As shown in Fig. 5, side-looking sonar can transmit and receive waves in The indicated area is explored. This sonar has excellent resolution in the navigational direction, and when exploring the ocean floor, you can obtain what can be called an underwater bird's-eye view. The undulations are displayed in detail with shading, allowing you to accurately determine the quality of the ocean floor. However, this sonar has the disadvantage that the depth and horizontal distance to the detected object are inaccurate due to the above-mentioned phase difference between the two receiving systems.

On the other hand, in the scanning sonar, as shown in FIG.
A fan-shaped wide (90°) transmitting beam 101 is formed in the direction of both sides, while a receiving beam 101 is wide (20°) in the bow direction and narrow (2°) in the lateral direction so as to be orthogonal to this transmitting beam 101. By forming a wave beam 102 and laterally scanning the receiving beam 102, the region Z by the transmitting beam 101 is sequentially explored. It has the advantage of being able to accurately detect the depth and horizontal distance of objects directly below the ship, but the resolution deteriorates further away to the sides where the angle of depression becomes smaller.
As a result, the detailed ups and downs of the ocean floor cannot be seen, and the depth and horizontal distance are inaccurate.

[0016] As described above, since high resolution can be obtained in the direction directly below the ship in scanning sonar, we attempted to correct the phase difference between the two wave transmitting and receiving systems in side-looking sonar using accurate exploration results in the direction directly below the ship. The specific configuration thereof will be explained in the examples.

[0017]

[Embodiment] FIG. 7 is a control block diagram showing an embodiment of the side-looking sonar of the present invention.
Only the portion that detects the phase difference in the reception system of the two receivers R1 and R2 on the starboard side is shown, and the configuration on the port side is the same. R1 and R2 are the above-mentioned wave receivers, both of which are composed of I ultrasonic transducers, and one of the wave receivers R2 is used for both transmitting and transmitting waves. 3 is a trigger pulse generator that generates a trigger pulse; 4 is a trigger pulse generator 3;
This is a transmission amplifier that supplies transmission power to the receiver R2 using a trigger pulse. 5 and 6 are receiving amplifiers that amplify I received signals detected by the receivers R1 and R2, respectively. Zero cross rise detectors 7 and 8 detect the point in time when the output signals from the reception amplifiers 5 and 6 cross the zero point from negative to positive, and output a pulse. 9 is a clock pulse circuit that generates clock pulses, 10 is a counter, and a zero cross rise detector 8
When this pulse is input as a reset signal, the clock pulses from the clock pulse circuit 9 are counted from 0. A latch circuit 11 latches the count value of the counter 10 when the pulse from the zero cross rise detector 7 is input as a set signal, and the value is sent to the adder 12 and the memory 13.

14 is a clock pulse circuit; 15 is a clock pulse circuit;
is a counter that counts clock pulses from the clock pulse 14 from 0 when the trigger output from the trigger pulse generator 3 is input as a reset signal. The count value is supplied to the switch 16 and is also input to the comparator 17 for comparison with the Rmax value,
The output signal of the comparator 17 is sent out as a switching signal from the switch 16 and is also input to the pulse generator 18 .

Reference numeral 21 denotes a CPU, which performs calculations as will be described later in accordance with a control program stored in the ROM 27. 22 is an input device, into which signals from a high-precision positioning device 23 for detecting the position of the ship, a direction measuring device 24 for detecting the direction, and a keyboard 25 are input;
A trigger pulse from the trigger pulse generator 3 and a memory completion pulse output from the pulse generator 18 are input. 26 is a RAM that stores various data necessary for calculations by the CPU 21 at any time. Reference numeral 28 is a contour line ROM which is a depth information storage means, and is a ROM containing the position of each contour line expressed in latitude and longitude, and by accessing the position, the depth of the ocean floor at that point can be obtained. Reference numeral 29 denotes an output device, which sends the value of -dφ determined by the CPU 21 to the adder 12.

The operation of the control circuit having the above configuration will be explained. Time points T0, T2, and T4 shown in FIG. 8 indicate the transmission timing of the receiver R2, and when a trigger pulse is output from the trigger pulse generator 3 for transmission at time point T0, the counter 15 is set to "0". ” is reset to clock pulse circuit 1.
4 is counted, a transmitting signal is output from the transmitting amplifier 4, and the transmitting signal is output from the receiver R2 as shown in FIG.
An ultrasonic beam is transmitted that spreads out in a fan shape on the starboard side as shown in . By transmitting this ultrasonic beam, the echo from the seabed directly below the own ship is first detected by receiver R2.
Next, the signal is detected by the receiver R1 after a slight time difference, and the receiving amplifiers 6 and 5 output a signal as shown in FIG. With respect to the output signal of the reception amplifier 6, a zero-cross rise detector 8 detects a time point t1 when the zero level is crossed from negative to positive, and a pulse is output. By supplying this pulse as a reset signal to the counter 10, the counter 10 is cleared, the clock pulses output from the clock pulse circuit 9 are counted, and the count values are sequentially input to the latch circuit 11.

On the other hand, for the output signal of the reception amplifier 5, the zero cross rise detector 7 detects the time t2 when the zero level is crossed from negative to positive and outputs a pulse, and this pulse is used as a set signal. When supplied to the latch circuit 11, the latch circuit 11 latches the input count value. Therefore, the latch circuit 11 latches the number of clock pulses between time t1 and time t2. This number of pulses is
, R2 and the direction of the horizontal object. If the period of the pulse of the clock pulse circuit 9 is set to 1/360 of the period of the sound wave used, this time difference is the above phase difference φ'. This value φ' is input to adder 12 and memory 13. The phase difference φ' is obtained in the same manner between the subsequent time points t3 and t4, and as time passes, echoes from the seabed gradually moving away to the right from just below the own ship are detected one after another, and their echoes are detected one after another. The phase difference φ' is sent to the memory 13.

On the other hand, since the count value of the counter 15 is sent as an address to the memory 13 via the switch 16 and a write signal is applied via the switch 16, the count value is not input to the memory 13. The phase differences φ' are stored one after another at predetermined addresses. Further, after time T0, the CPU 21 performs the operations shown in the flowchart of FIG. 10 in parallel.

That is, when the trigger pulse from the trigger pulse generator 3 is input to the CPU 21 via the input device 22, the process proceeds from step S1 to step S2, where the automatic output from the high-precision positioning device 23 and the direction measuring device 24 is inputted to the CPU 21 via the input device 22. The ship's position measurement and navigational direction are read, and based on these values and the search range previously entered on the keyboard 25 (in this example, 1000 m on both sides), on the starboard side in the contour map shown in FIG. The intersection point A with the contour line in the exploration range of
Find B, C, D, and E. In the next step S3, the horizontal distance h to each of the above-mentioned intersection points is determined, and by inputting this h and the current depth d (value of the contour line) into equations (6) and (7), the received wave The distance r from the center of the vessels R1 and R2 to the sea surface below each intersection point is determined, and the phase difference φ" at that time is determined from equation (2). In step S4, the counter 15
The count value becomes Rmax and the pulse generation circuit 18 waits for a time point T1 at which a memory completion pulse is output. Note that the processing time of step S2 and step S3 is short, and has already ended at time T1 when the memory completion pulse is output.

Now, at time T1, a switching signal is sent from the comparator 17 to the switching device 16, and the contact point of the switching device 16 is switched to the right, so that the CPU 21 switches the switching device 16 in step S5. memory 13 through
In order to read out the measured phase difference φ' at the distance r, a predetermined address signal R is sent to the memory 13 to read out the phase difference φ with respect to the intersection points A to E stored in the memory 13. ' are read sequentially. Here, r=R×Δr. If Δr is the input clock pulse period tp of the counter 15, then Δr=c・tp/2
becomes. As can be seen from the above explanation, from time T0 to T
1 is the echo capture period, therefore, the comparator 1 is set so that echoes from the desired range are detected during this period.
The setting value of Rmax for 7 is determined. Note that the comparator 17 switches the switch 16 to the left when the count value of the counter 15 becomes 0.

FIG. 12 shows the actually measured phase difference φ' (indicated by the symbol ●) and the phase difference φ'' (indicated by the symbol) obtained from the contour map for each intersection point A to E. In S6, the corresponding phase differences are subtracted, φ'-φ'', at each of these intersection points, and the average value thereof is taken as the above-mentioned phase difference shift dφ. The processing time of steps S5 and S6 is short, and ends at time T2 when the next trigger pulse is output.

By sending this phase difference shift -dφ to the adder 12 via the output device 29, the adder 12 calculates φ'-dφ, and both receivers R
1, the phase difference φ at the time of incidence of R2 is output. Note that the phase difference φ' corrected here will be corrected by -dφ obtained in the previous transmission, but in a short time like the transmission interval, dφ
There is no problem because the value of does not change. If you want to correct the current phase difference φ' with dφ based on the current transmission, use two memories 13 and store the next phase difference φ' in one memory at the time of the next transmission, and at the same time Phase difference φ'
It is sufficient to read out according to the value of the counter 15 and correct it by dφ.

An embodiment of the side-looking sonar according to the second invention is shown in FIGS. 13 and 14. In FIG. 13, parts different from those in FIG. 7 will be described. 31 is an M-ary H counter which has the same value as the number M of received beams in a scanning sonar, which will be described later, and when the trigger output from the trigger pulse generator 3 is input as a reset signal, Pulse to 0
Count from The count value is supplied to the switch 46 in FIG. 14 and sent as a switching signal to the switch 43 in FIG.
A carry pulse is sent to the R counter 15. The R counter 15 is an N-ary counter, and counts carry pulses from the H counter 31 from 0 when the trigger output from the trigger pulse generator 3 is input as a reset signal. The count value is supplied to the switch 16 and the switch 46 in FIG.
max<N) is input to a comparator 17 for comparison with the value. The output of this comparator 17 is sent to the pulse generator 18 and the switch 1.
6 and the switch 46 of FIG. 14 as switching signals. A memory completion pulse output from the pulse generator 18 is input to the input device 22 .

FIG. 14 shows an embodiment of a scanning sonar section added to the side-looking sonar shown in FIG. 13. R3 and TX are a receiver and a transmitter, and as shown in the developed view of FIG. 15, the receiver R3 has j ultrasonic transducers arranged in a direction perpendicular to the navigation direction. The transmitter TX has k ultrasonic transducers arranged in the navigation direction. R1 and R2 on the right side are the receivers in FIG. 13, and R1' and R2' on the left side are the receivers on the port side.

40 is a transmitting amplifier, and 41 is a receiving amplifier that amplifies the received signals from the j ultrasonic transducers of the receiver R3. Reference numeral 42 denotes a phase synthesis circuit, which forms M receiving beams that are sequentially scanned in the lateral direction by phase-combining the received signals of the j systems using a known technique, as shown in FIG. do. The switch 43 sequentially takes out the M received beams formed by the phase synthesis circuit 42, digitizes them with the A/D converter 44, and supplies them to the memory 45.

The operation of the control circuit having the above configuration will be explained again with reference to FIGS. 8 and 9. Time points T0, T2, shown in FIG.
T4 indicates the transmission timing of the receiver R2 and the transmitter TX, and when a trigger pulse is output from the trigger pulse generator 3 for transmission at time T0, the R counter 1
5 and H counter 31 are reset to "0", and a transmission signal with predetermined power, pulse width, and frequency is output from the transmission amplifiers 4 and 40, and the transmission signal is outputted to the receiver R2.
As shown in FIG. 5, a transmitting beam 100 is formed that spreads in a fan shape to the starboard side, and the transmitter TX forms a transmitting beam 101 that spreads in both starboard directions as shown in FIG. . Then, the detection signals reflected from the seabed are received by receivers R1, R2, and R3, and received by receiving amplifiers 5, 6, and 41.
is amplified.

In the side-looking sonar shown in FIG. 13, by transmitting an ultrasonic beam, the echo from the seabed directly below the own ship is first detected by the receiver R2, and then the echo is received after a slight time difference. is detected by the receiver R1, and the receiving amplifier 6,
5 outputs a signal as shown in FIG. With respect to the output signal of the reception amplifier 6, a zero-cross rise detector 8 detects a time point t1 when the zero level is crossed from negative to positive, and a pulse is output. By supplying this pulse as a reset signal to the counter 10, the counter 10 is cleared, the clock pulses output from the clock pulse circuit 9 are counted, and the count values are sequentially input to the latch circuit 11.

For the output signal of the reception amplifier 5, the zero cross rise detector 7 detects the time point t2 when the zero level is crossed from negative to positive and outputs a pulse, and this pulse is sent to the latch circuit as a set signal. 11, this latch circuit 11 latches the input count value. Therefore, the latch circuit 11 latches the number of clock pulses between time t1 and time t2. This number of pulses is
This is the time difference caused by the mounting position of the 1 and the direction of the horizontal object, and if the period of the pulse of the clock pulse circuit 9 is set to 1/360 of the period of the sound wave used, this time difference is expressed by the above phase difference φ'. , this value φ' is input to the adder 12 and the memory 13. The phase difference φ' is obtained in the same manner between the subsequent time points t3 and t4, and as time passes, echoes from the seabed gradually moving away to the right from just below the own ship are detected one after another, and their echoes are detected one after another. The phase difference φ' is sent to the memory 13.

On the other hand, in the scanning sonar section shown in FIG. 14, echoes from the ocean floor are received by the receiver R3 due to the waves transmitted by the transmitter TX. These J reception signals are phase-combined by a phase synthesis circuit 42, and M reception beams having different scanning angles are formed. By controlling the switching device 43 by the switching signal from the H counter 31,
A received beam in the direction indicated by the count value of the H counter 31 is selected from among the M received beams, and the received beam is sent to the A/D converter 44.
The data is stored in the memory 45 via.

The operation of the scanning sonar will now be described in more detail with reference to FIG. θsm indicates the angle of the m-th beam from the direct direction d (+ on the starboard side),
θsm=Δθs{(M-1)/2-m}, where M is an odd number and the (M-1)/2nd beam is directly below. Rm indicates the position in the R direction in the memory 45 of the ocean floor existing in the m-th beam. rm is the straight line distance (
The unit is m), and rm=Δr×Rm. hm, dm
are the horizontal distance and progress of the seabed from the own ship that existed within the m-th beam. hm indicates + for the starboard side, and dm indicates + for the downward direction, and both units are meters. hm=rm×sinθsm, dm=rm×cosθsm
There is a relationship between Also, Δr is the memory 13 and the memory 45
If the period of the carry pulse outputted by the H counter 31 at intervals in the r direction (distance direction) at which data is taken in is tp, then Δr=c·tp/2.

Returning to FIGS. 13 and 14, the memory 13 and the memory 45 each store one transmission of the side-looking sonar phase difference and the scanning sonar detection signal for each Δr(m) up to rmax. rmax is the straight line distance from the ship sufficient to reach the seabed even at the beam end in FIG. 5 in the ocean area where the device of the invention is used. Here, rmax=Rmax×Δr. The number of output bits of the latch circuit 11 and A/D converter 44 is β1, β
2, the storage capacities of the memories 13 and 45 are β1×Rmax and β2×Rmax×M, respectively.

Between T0 and T1 until the count value of the R counter 15 reaches Rmax, the switches 16 and 46 are switched to the left as shown in the figure. Since the phase difference φ' input to the memory 13 is sent as an address to the memory 13 via the switch 16 and the write signal is applied via the switch 16, the phase difference φ′ input to the memory 13 is stored one after another at predetermined R addresses.

On the other hand, H counter 31 and R counter 1
Since the count value of 5 is sent to the memory 38 via the switch 46 and the write signal is applied via the switch 46, the detection signal input to the memory 45 is set to the predetermined R and They are stored one after another at the address determined by H.

Now, at time T1, the memories 13, 45
When the writing of the signal to is completed, a switching signal is sent from the comparator 17 to the switching devices 16 and 46, and the switching device 16,
At the same time that the contact 34 switches to the right, a memory completion pulse from the pulse generator 18 is sent to the C via the input device 22.
When the input is input to the PU 21, the CPU 21 proceeds from step S11 to step S12 in FIG. Or rma
A predetermined address signal is sent to the memory 45 in order to read out the detection signals up to x. In other words, the H address is m,
Let the R addresses be Rmax-1 in order from 0.

Next, among the Rmax detection signals read out,
For example, the position where the maximum detection signal exists, that is, the R address value Rm, is set as the seabed position. Then, calculate rm, dm, and hm from Rm and θsm, and calculate the phase difference φ” at that time (2
), (4), (6), and (7). Furthermore, Figure 1
7 and the 0 point in FIG. 3 are considered to match.

Next, in step S13, the CPU 21 sends a read signal to the memory 13 via the switch 16, and sends an address signal of Rm to the memory 13, thereby reading the information for rm stored in the memory 13. Read out the phase difference φ'. This is repeated for the right half beam of the scanning sonar, that is, from m=0 to (M-1)/2.

As can be seen from the above explanation, the period between time T0 and T1 is the echo capture period, and therefore, the setting value of Rmax for the comparator 17 is set so that echoes from a desired range are detected during this period. It can be decided.

FIG. 18 shows the phase difference φ” (indicated by the symbol) actually measured by the scanning sonar and the phase difference φ” (indicated by the symbol) obtained by the side-looking sonar at the same distance.
In step S4, subtraction of both phase differences, φm'-φm'', is performed at each of these points, and the average value thereof is set as the above-mentioned phase difference shift dφ. The processing time of step S14 is short, and ends at time T2 when the next trigger pulse is output.

By sending this phase difference shift -dφ to the adder 12 via the output device 29, the adder 12 calculates φ'-dφ, and both receivers R
1, the phase difference φ at the time of incidence of R2 is output. Note that the phase difference φ' corrected here will be corrected by -dφ obtained in the previous transmission, but in a short time like the transmission interval, dφ
There is no problem because the value of does not change. If you want to correct the current phase difference φ' with dφ based on the current transmission, use two memories 13 and store the next phase difference φ' in one memory at the time of the next transmission, and at the same time Phase difference φ'
may be read out according to the value of the R counter 15 and corrected by dφ. In the above embodiment, the frequencies of the ultrasonic pulses transmitted from the transmitter TX and the receiver R2 must be different so as not to interfere with each other, but the frequencies of the ultrasound pulses transmitted from the transmitter TX and the receiver R3 are the same. frequency, and the receiver R
1 and R2 are the same. Moreover, the receivers R1, R2,
It is also possible to omit the transmitter TX by making R3 all of the same frequency.

[0044]

[Effects of the Invention] As explained above, in the first invention,
For a certain measurement point that has been accurately measured in advance, by calculation,
Obtain the phase difference φ' at the input points of the two receivers, and then calculate the phase difference φ' between the two receivers at the same measurement point.
We measured φ'-φ”=dφ as the phase shift between the two receiving systems, and the phase difference actually measured after this point was corrected by this phase shift dφ. It is possible to remove the phase difference shift that occurs between the receiving systems, and therefore the position of an underwater object can be accurately measured.The second invention uses accurate information using a scanning sonar instead of the above-mentioned previously measured seabed depth information. This device uses depth information, and can perform accurate underwater detection in real time.

[Brief explanation of drawings]

[Figure 1] Perspective view showing the beam formed by side-looking sonar

[Figure 2] Diagram showing an example of installing a transducer in a side-looking sonar

[Figure 3] Diagram used to explain the operating principle of side-looking sonar

[Figure 4] Diagram used to explain the principle of the present invention

[
Figure 5 Diagram showing transmission and reception beams in side-looking sonar

[Figure 6] Diagram showing transmission and reception beams in scanning sonar

[Fig. 7] Control block diagram showing an embodiment of the side-looking sonar of the first invention.

[Figure 8] Time chart showing the operation of the control block diagram in Figure 7

[Figure 9] Time chart showing the operation of the control block diagram in Figure 7

[Figure 10] Flowchart showing the operation of the control block diagram in Figure 7

[Figure 11] Diagram showing the intersection with the contour map within the exploration range in the starboard direction

[Figure 12] Graph showing the phase difference obtained through actual measurements and the phase difference obtained based on data from contour lines

[Figure 13]
A control block diagram showing an embodiment of the side-looking sonar of the second invention

FIG. 14 A block diagram showing an embodiment of the scanning sonar section added to the device in FIG. 13.

[Figure 15] Developed view showing an example of how the transducer is installed in the device shown in Figure 13

[Figure 16] Flowchart showing the operation of the device in Figure 13

[Figure 17] Diagram used to explain calculation of phase difference in the device in Figure 13

[Figure 18] Diagram showing beam scanning in scanning sonar

[Explanation of symbols]

R Receiver 3 Trigger pulse generator 4 Transmission amplifier 5 Reception amplifier 6 Receiving amplifier 7 Zero cross rise detector 8 Zero cross rise detector 9 Clock pulse circuit 10 Counter 11 Latch circuit 12 Adder 13 Memory 14 Clock pulse circuit 15 Counter 16 Switcher 17 Comparator 18 Pulse generator 21 CPU 22 Input device 23 High precision positioning device 24 Direction measuring device 25 Keyboard 26 RAM 27 ROM 28 Contour line ROM 29 Output device 31 Counter TX Transmitter 40 Transmission amplifier 41 Receiving amplifier 42 Phase synthesis circuit 43 Switcher 44 A/D converter 45 Memory 46 Switcher

Claims (2)

[Claims] Claim 1: A pair of first and second wave receivers provided at positions a predetermined distance apart on a straight line forming a predetermined angle with a vertical line; forming a transmitting beam that is wide in the direction and narrow in the horizontal direction, and capturing echoes of the beam in first and second receivers; The phase difference between both received signals obtained from the second receiving circuit is detected by a phase difference detection means, and the depth of the detected object and the reception from the own ship are determined based on the phase difference and the time required for the echo to return. In a side-looking sonar that calculates and displays the horizontal distance to a detected object, a depth information storage means stores pre-measured seabed depth information; phase difference φ'
and the depth of the first and second receivers determined from the depth read from the depth information storage means for the same measurement point as above, and the horizontal distance of the ship's position from the measurement point obtained by the positioning device. From the phase difference φ” at the input point, the first
Due to the difference in phase characteristics between the first receiver and receiving circuit and the second receiver and receiving circuit, φ'-φ''=dφ is calculated as the phase shift that occurs between the signals passing through both receiving systems. A side characterized by comprising: a phase shift calculation means; and a correction means for correcting the phase difference detected by the phase difference detection means during measurement with the phase shift dφ calculated by the phase difference calculation means. Looking sonar. 2. A pair of first and second wave receivers provided at positions a predetermined distance apart on a straight line forming a predetermined angle with the vertical line; forming a transmitting beam that is wide in the direction and narrow in the horizontal direction, and capturing echoes of the beam in first and second receivers; The phase difference between both received signals obtained from the second receiving circuit is detected by a phase difference detection means, and the depth of the detected object and the reception from the own ship are determined based on the phase difference and the time required for the echo to return. In a side-looking sonar that calculates and displays the horizontal distance to a detected object, a large number of pencil-shaped transmitting and receiving beams that partially overlap with the transmitting and receiving beams of the side-looking sonar are formed below and to the sides of the own ship, and echoes return. a depth information input unit that receives the depth and horizontal distance measured by a scanning sonar that calculates the time required for the detection, the depth of the detected object from the direction of each pencil beam, and the horizontal distance from the own ship to the detected object; The phase difference φ' detected by the phase difference detection means with respect to an echo from a certain measurement object underwater, and the depth and horizontal distance to the same measurement object inputted to the depth information input section. Phase difference φ at the input points of the first and second receivers
”, due to the difference in phase characteristics between the first receiver and receiving circuit and the second receiver and receiving circuit, the phase shift between the signals passing through both receiving systems is φ'−φ. ”
= dφ; and correction means for correcting the phase difference detected by the phase difference detection means during measurement with the phase shift dφ calculated by the phase difference calculation means. Side-looking sonar featuring: