JPS5931021B2 - sonar device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ner device that measures the distance and direction of an underwater target, and a ner device that corrects target ranging errors due to rotating directional beam transmission.

In a sonar device, generally, as shown in Fig. 1, n
The direction and distance of the target are measured by transmitting and receiving the rotating directional beam using the main directional beam Bo-Bo-Bm.

The rotating directional beam transmission method can improve the detection distance, but it is accompanied by a distance error.

That is, when the directional beam is turned from B-o to Bm at a sector angle θ8 as shown in FIG. 2, the sector center azimuth θ.

is the reference direction, and the directional beam B is placed in that direction.

The distance of the reflected wave when the directional beam is oriented in another direction (with reference to the pulse transmitted when the directional beam is oriented in the other direction (Fig. 3A)) should also be measured.

Therefore, the sector center orientation θ.

When the target 11 is located in the azimuth .theta., the transmission signal of the directional beam Bi directed in that direction due to the rotation is reflected by the target and is received.

When the directional beam finishes transmitting pulses in the given direction, it turns by a predetermined angle to transmit pulses, and repeats the process of transmitting and turning to transmit a predetermined sector angle θ8.

Therefore, the start of transmission of the transmission pulse Pi of the directional beam Bi is as shown in FIG. 3B, the transmission pulse P in the reference direction.
.

It is delayed by time t1 from the start of transmission (FIG. 3A).

The received signal for the transmitted pulse Pi of the beam Bi is as shown in FIG. 3C, and the echo sound from the target 11 is received after a time t1 from the start of transmission of the transmitted pulse Pi.

Therefore, when C is the underwater sonic speed of a sound wave, the target distance 1iIR is R=Ct, /2.

Normal rotating directional beam transmission/reception is based on the sector center azimuth θ, as described above.

beam B. Beam Bm from beam B-□ centering on
A sound wave with a pulse width T (seconds) is transmitted for each beam until
In total, 2 m + 1 pieces are transmitted, beam B.

The target distance is calculated from the time to the target echo signal received with reference to the transmission start point.

Therefore, the sector center orientation θ.

Although the distance measurement value for a target located at the sector center direction is accurately measured, an error occurs in the measured value for a target located at a direction different from the sector center direction.

To explain this relationship in more detail, looking at the received signal of beam Bi shown in FIG. 3C, beam B.

The time from the start of transmission to the target echo signal 12 is the target distance from ct'c R1 knee (1, +12)...
・It is calculated as (1)2.

Since t2 is t2=TXi, this relationship and R
Substituting 2Ct1/2, R'2R+-(T X i
) =”” (2).

Now, if we set the second term on the right side of equation (2) as △R, then △R=-(T
Xi)・・・・・・・・・・・・・・・(3)

This is the distance error caused by the rotating directional beam transmission.

This distance error is the beam center azimuth θ.

From the beam Brn side, the right side in Figure 2 is a distance error of ten signs, the measured distance is a dog of the actual target distance, and on the beam Brn side, the left beam in Figure 2 is a distance error of one sign, The measured distance will be smaller than the actual target distance.

Conventionally, distance measurement errors have been ignored, but due to demands for an increase in the transmission pulse width T, an increase in the number of transmission beams, and an improvement in measurement distance accuracy, the distance measurement errors can no longer be ignored. Ta.

This invention reduces such distance errors to small to zero.According to this invention, the reflected reception signal is stored in a storage device using the direction and distance as an address, and the reflected reception signal is stored in a storage device as an address, and when transmitting between the reference direction and each direction. The distance address when writing or reading from the storage device is corrected according to the turning time of the directional beam.

When displaying a received signal on a cathode ray tube, the operation of temporarily storing the received signal in a storage device, reading out the stored information in synchronization with the deflection signal of the display (cathode ray tube), modulating the brightness, and displaying the signal is at the flicker limit. Frequency or higher is displayed repeatedly and constantly.

The storage device in that case can be used for the above correction.

This constant display type tuner device will be described with reference to FIG.

A transmission start pulse 15 is sent from the control circuit 14 to the transmission controller 16.
The transmission controller 16 controls the transmission/reception converter 18 to switch between transmission and reception using the transmission/reception switching signal 11, and also transmits the beam transmission scanning signal 21 triggered by the transmission timing signal 19 from the control circuit 14. Send the scanner 2
Send to 2.

The transmission scanner 22 sends transmission beam forming signals from beam B-1 to beam Bm shown in FIG. 2 to the transmitter 23,
The power-amplified transmission signal 24 is sent to the transducer 25 via the transducer 18, where it is transmitted as a rotating directional beam and radiates a sound wave pulse into the water.

The echo sound from the target is converted into an electrical signal by the transducer 25, and this received signal is transmitted as the transmission/reception switching signal 1 after transmitting the beam Bm.
1, the signal enters the reception state and is supplied to the receiver 26 through the transmitter/receiver converter 18.

The receiver 26 is of a so-called standby/reception type, and has a reception beam that divides 360° in the circumferential direction into n equal parts, and the reception signals of the n channels of reception beams are individually detected and integrated.

The received signal of the n channel is a sampling pulse 28 with a period of 2t/2C determined by the distance resolution t of the display 2γ and the underwater sound speed C from the time of generation of the channel 1 transmission start pulse 15 from the control circuit 14 to the scanner 29. The scanner 29 sequentially switches the received output of the receiver 26 from channel 1 to channel n and supplies it to the A/D converter 31, and the received signal converted into a digital signal is sent to the scanner 29.
The data is temporarily stored in an area of the storage device 34 determined by a write direction address 32 that matches the switching channel and a write distance address 330 determined by the number of sampling pulses.

This memory operation is performed from the start of channel 1 transmission to the sonar device's set detection range R at a sampling period of t (seconds).
/ is repeated several times, ending the -probing period.

- When the search is completed, the control circuit 14 generates the transmission timing signal 19 again to perform the rotating directional beam transmission,
In the receiving state, new data is sequentially updated in the corresponding storage area of the storage device 34, and old data is discarded.

On the other hand, as shown in Figure 5A, the display method of a sonar device is PPI, in which the radial direction is the distance and the circumferential direction is the direction.
Or, as shown in Figure B, the B Kuko-1 display, in which the vertical direction is the distance and the horizontal direction is the direction, is generally used.

A deflection signal 35 that divides the distance direction into t divisions and the azimuth direction into n divisions in the PPI display or B Kuko-1 display is generated by the deflection circuit 38 based on the distance position signal 36 and the azimuth position signal 31 generated by the control circuit 14, and is generated by the cathode ray tube. The electron beam of the display 21 is deflected.

The write/read switching control pulse 39 generated by the control circuit 14 puts the storage device 34 in the write state during the storage operation, and immediately switches it to the read state when the storage operation is completed, as determined by the deflection signal 35. The received signal stored in the readout azimuth address 32 and distance address 33 indicating the same position as the azimuth and distance is read out, and the D/A converter 4
1, and this analog signal 42 is transmitted through a video amplification circuit 43 to a position on the display surface of the display device 2γ determined by the deflection signal 35 by modulating the brightness of the electron beam of the display device 2γ. An image whose brightness changes depending on the intensity is displayed.

This readout and display operation is performed by sequentially displaying all pixels in the distance direction, n pixels in the azimuth direction, and Xn pixels in a display pattern as shown in FIG. 5A or B. By repeating the process at a frequency above El (30 Hz), a flicker-free image is constantly displayed over the entire screen.

In the device shown in Fig. 4, sampling pulses are generated based on channel 1 (or a specific channel), and the n-channel received signals are sequentially A/D converted to the same distance address. The information stored in this manner is temporarily stored in the storage device 34, and the information thus stored is read out and displayed at all times.

Therefore, as described above, in the case of rotating directional beam transmission, the reception signals of each channel (or each beam) are received at the same time, but the distance of the echo sound is different, so that a distance error occurs for each channel.

The main parts of an embodiment of the receiver device according to the present invention are shown in FIG. 6, in which parts corresponding to those in FIG. 5 are given the same reference numerals.

In this invention, a distance correction circuit 45 is provided for distance correction.

This distance correction is performed by correcting the distance address when writing to or reading from the storage device 34.

First, a case will be described in which the distance address at the time of writing to the storage device 34 is corrected for each direction.

The distance correction circuit 45 knows i in the above equation (3) from the beam center azimuth signal 46 from the control circuit 14 and the azimuth address 32 (same as the receiving direction), calculates ΔR in this equation (3), and calculates △R of the distance address 33 from the control circuit 14
A corrected distance address 41 is created by subtracting from , that is, a corrected distance address 41 is created by making a correction according to the time required for the directional beam to turn during transmission between that direction and the reference direction, and this corrected distance address 41 is subtracted from The A/D is stored in the area of the storage device 34 determined by both the azimuth address 32 and the azimuth address 32.
The output of the converter 31 is temporarily stored.

On the other hand, when reading for constant display, the switching control pulse 39
Otherwise, the distance address 33 is given to the storage device 34 as the distance address 41 without being subjected to the above correction, and a read operation is performed to display an image.

Therefore, the received signal is corrected for the distance at the time of writing and is stored in the storage device as an omnidirectional accurate distance address.

Next, a case will be described in which the distance is corrected at the time of reading the received signal from the storage device 34.

In FIG.
Do it by T.

On the other hand, when reading for constant display, △R calculated from the beam center azimuth signal 46 and the azimuth address 32 is added to the distance address 33 to create a corrected distance address 41, and both addresses of the corrected distance address and the azimuth address are added to the distance address 33. The received signal is read out from the area of the storage device 34 determined by and displayed.

Therefore, when displaying an image, the distance is corrected and an accurate image is displayed in all directions.

□ These distance address corrections during writing and distance address correction during reading can be performed in the same way in principle, and although there are slight differences depending on the display method etc. Since the number of times of reading is greater than the number of times of writing and is faster, it is easier to implement a method of correcting the distance address during writing, which requires relatively slow calculation time.

The above operation will be explained in detail with reference to FIG. 1. As shown in FIG. 1A, B, and C, the transmission pulses are the transmission pulses P-i of the beam B-i and the transmission pulses P-i of the beam B-i.

transmission pulse P. is delayed by Ti, and the transmitted pulse Pi of beam Bi is P.

lags behind by Ti.

Each received signal of beam B-itBotBi is shown in Fig. γC and D.
, E, and the distances of the received signals sampled at time tj are R-ij and Roj2Rj for beam B-i+B□tBi, respectively.

Rlj, and using the distance correction △Ri (.), the distances will be Rj + △R1, Rj, Rj - △Ri, respectively, so the storage device 34 has the distance address indicated by diagonal lines as shown in FIG. 8A. The distance is corrected and stored.

That is, the received signal of beam B-i at time tj is stored in an area determined by azimuth address -1, distance address R-ij, two Ri+ΔRi.

Note that in FIGS. 1C, D, and E, each Ri indicates the time point at which the actual target distance is Ri when the received signal is received.

In the case of FIG. 8B, the received signal sampled at time tj is beam B-iB□tB at the position of distance address tj.
The received signal of i is stored in the hatched address of the storage device 34.

The time points at which the received signals at the distance Rj with respect to the beam B-i)B□tBi are read are each at the distance address tj-△RI.
The distance is corrected by ttJytj+ΔRi and the readout image is displayed.

In addition, when detecting a target echo image from the image received by the scanner, the memory device is sequentially updated and displayed from the time the transmission pulse is sent and the previous detection image that is always displayed. By monitoring while making comparisons, the detection probability becomes much better than detecting from only the current detection images.

Although this is called an integral effect, the sector center direction of the transmitted rotating directional beam may be sequentially shifted, but even in that case, according to this embodiment, this integral effect can be effectively utilized.

That is, first of all, if we consider the simplest situation in which the own ship and the target are stationary, in this embodiment, even if the transmitting/receiving sector center direction is set to an arbitrary direction, the distance of the target is corrected, so the cathode ray tube display screen Always displayed in the same position above.

However, in the conventional constant display method shown in FIG. 4, the distance to the target is determined as shown in FIG. 3 depending on the direction of the sector center.

The target position will change depending on the target's transmitted beam, and the target position on the cathode ray tube display screen will not be constant and an integral effect will not be obtained.Also, even if the own ship and the target are moving, the target will move at regular intervals. As a result, an integral effect can be expected.

As explained above, according to the present invention, accurate target distance can be obtained by correcting the distance error caused by rotating beam transmission, and at the same time, the integral effect of the constant display can be effectively used, and the probability of detecting the target can be increased. You can do it together.

In the above, this invention was applied to the constant display method, but
In short, the received signal is stored as an azimuth and distance address, and the distance error is corrected by correcting the distance address when writing or reading the signal.

[Brief explanation of drawings]

Figure 1 is a diagram showing the arrangement of transmitting and receiving beams in a sonar device, Figure 2 is a diagram showing the relationship between the sectors of rotating directional beam transmitting and receiving and the beam to the target, and Figure 3 is a diagram showing the relationship between the transmitted signal and the received signal in Figure 2. 4 is a block diagram showing a conventional always-on display type sonar device, FIG. 5 is a diagram showing a sonar display format, and FIG. 6 shows a main part of an embodiment of a sonar device according to the present invention. FIG. 1 is a waveform diagram for explaining the operation of FIG. 6, and FIG. 8 is a diagram showing a correction distance address. 18... Transmitter/receiver converter, 23... Transmitter, 25...
Transducer/receiver, 26... Receiver, 2γ... Display, 29
...Scanner, 31...A/D converter, 34...Storage device, 45...Distance correction circuit.

Claims (1)

[Claims] 1 In a rotating directional beam transmission sonar device that transmits a rotating directional beam, receives the reflected wave for each direction and distance, and writes the received signal in a storage device with the direction and distance as an address, the above rotating directional beam is used. means for calculating each distance error caused by the turning time of the directional beam during transmission between the reference direction and each direction from the difference between the address of the reference direction for beam transmission and the direction address; 1. A sonar device comprising a distance correction circuit comprising means for correcting one of the read distance addresses by adding or subtracting the distance error corresponding to each direction.