JPH0412830B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a PPI sonar that digitizes and displays the intensity of reflected waves. Conventional technology PPI sonar, which displays the situation all around 360 degrees,
Ultrasonic key impulses are emitted at angles at regular intervals, and the reflected key impulses are strengthened to display the state of the ocean or the ocean floor. Problems to be Solved by the Invention Ultrasonic waves, which are the key impulse, have a speed of about 1500 m/s in seawater, so when trying to observe a situation at a distance of 750 m, for example, it is necessary to It cannot be done in time. Therefore, in order to display the entire circumference, measurements must be repeated by changing the angle every second.
At this time, if the change in angle is small, the number of measurements will increase, so it will take a long time to obtain received data covering 360 degrees. This means that when the measurement target moves, the display does not correspond to the change. If the change in angle is large, changes in the position of the target can be accommodated, but the display becomes a series of received data extending radially with rough angular intervals, making it difficult to see. The present invention was conceived to eliminate this difficulty in viewing, and aims to provide a PPI sonar that can easily display received data over the entire circumference obtained in a short period of time. Means for Solving the Problems The PPI sonar according to the present invention emits key impulses at constant intervals θ in the circumferential direction, and sequentially measures the intensity of the reflected wave for each key impulse at intervals of time corresponding to the distance. In a PPI sonar that obtains multiple pieces of received data expressed by n-bit weights by performing D conversion and displays the PPI of this received data,
When p and q are natural numbers and r is an integer (0≦r≦q+1), the adjacent angles at which key impulses are emitted are expressed as pθ and (p+1)θ,
The received data at the same distance at this angle is A _p ,
A _p+1 , and q between pθ and (p+1)θ
The angles divided into equal parts are θ1 (= pθ), θ1…θr…θq, θ(q
+
1) If [=(p+1)θ] and the interpolated data corresponding to the received data at the same distance as above at these angles are B ₀ , B ₁ ...B _r ...B _q , B _q+1 , then the received data is Interpolated data B ₁ …B _r based on A _p , A _p+1
…A signal processing unit that calculates B _q and received data A _p ,
A _p+1 and interpolation data B ₁ ...B _r ...B _q are both displayed _. When expressed as a graph of the curve _r = F (θr),
A data table showing a graph of a curve connecting point (θ0, B ₀ ) and point (θ(q+1), B _q+1 ) is stored in data ROM for each n-bit weight related to interpolated data B ₀ , B _q+1. The data table of the graph corresponding to the actually obtained received data A _p , A _p+1 is read out from the data ROM, and interpolated data B ₁ ...B are stored in advance on the basis of the read data. It is characterized by being designed to calculate _r ...B _q . Function Key impulses are emitted at irregularly spaced angles in order to obtain received data over the entire circumference in a short period of time, but based on the received data obtained at that time,
Interpolated data is calculated from received data at adjacent angles at the same distance. This interpolated data is treated as data similar to the received data obtained from the reflected wave of the key impulse, and is displayed together with the received data as data that extends radially between the angles at which the key impulse was actually emitted. Embodiment FIG. 1 is a block diagram showing the electrical configuration of an embodiment of the present invention. In the figure, the output of the transducer 41 that receives the reflected wave of the key impulse is as follows:
The signal is guided to the receiver 11, amplified, detected, and sent to the A/D converter 12 as an intensity signal. The transmitter 22 generates a key impulse and sends it to the transducer 4.
1 causes the transducer 41 to vibrate. The transducer drive unit 23 is a mechanical drive device for rotating the transducer 41, changing the inclination angle, or storing the transducer 41 inside the hull when not in use. It operates according to signals from the control section 21. Further, the control unit 21 controls the timing at which the transmitting/receiving unit 22 emits the key impulse and the timing at which the receiving unit 11 performs amplification and detection, according to the output of the range setting unit 24, which is comprised of a range setting switch etc. provided for the pulse. It's on. The A/D converter 12 sequentially digitizes the intensity signal from the receiver 11 at time intervals corresponding to the range setting and outputs it as 3-bit received data. This received data is guided to the signal processing section 13. The signal processing unit 13 includes a buffer memory 33 that stores all received data corresponding to key impulses at two adjacent angles, a data ROM 31 that stores interpolated data groups, and a signal processing main unit that is configured by software. The signal processing section 32 outputs the received data and interpolated data to the coordinate transformation section 14 (details of the signal processing section 13 will be explained later). The above two pieces of data given in polar coordinates are written into the video memory 15 arranged in orthogonal coordinates after coordinate transformation. The video clock unit 25 sequentially generates read addresses in accordance with the scan timing of the display unit 17 and sends them to the video memory 15. The read data is converted into serial data by the video signal converter 16. After that, it is sent to the display section 17. Further, two horizontal and vertical synchronization signals are sent from the video clock section 25 to the display section 17. FIG. 2 is an explanatory diagram showing the relationship between received data and interpolated data. The figure shows a case in which interpolated data is calculated along two directions (in an actual machine, interpolated data is calculated in many directions so as to be displayed continuously). The key impulse is emitted in the direction 61, and its reflected waves become received data that is A/D converted at regular time intervals, but as time passes, it becomes received data at a position that moves away from the center O. . When receiving data up to the outer circumference 81, which indicates the longest distance, is obtained, the transducer 41 is rotated and a key impulse is emitted in the direction of 62 to obtain received data (in the actual machine, this rotation angle is set to 5 degrees). . At this time, there is no received data in the area 82 between the directions 61 and 62. Therefore, received data 6 at the same distance in directions 61 and 62, that is, received data 6 at the same distance from the center O.
Focusing on 3 and 64, these two received data 6
Interpolated data 73 and 74 are calculated from 3 and 64. Regarding the order of calculation of interpolation data, for example, when the rotation direction of the key impulse is clockwise,
First, the interpolation data 75 and 76 start from the center O of the direction 71 toward the outer periphery 81, and when the computation up to the interpolation data 77 is completed, the interpolation data is similarly computed along the direction 72. The interpolated data calculated in this way has the same number as each received data in the directions 61 and 62, and it is as if a key impulse was emitted in the directions 71 and 72 and received data obtained from the reflected wave. Interpolated data is obtained in a certain order. FIG. 3 is an explanatory diagram showing the relationship between the values of received data (indicated by white circles) and the values of interpolated data (indicated by black circles). The vertical direction in FIG. 3 shows the strength of received data and interpolated data expressed by 3-bit weights. The horizontal direction in FIG. 3 is the direction of the angle 0 to 11, which is obtained by dividing the angle in the direction 61 and the angle in the direction 62 shown in FIG. 2 into 11 equal parts.
In the figure, actually obtained direction 0 (direction 61), direction 1
1 (direction 62) is shown as n0, n11, while the direction 1~ determined by calculation is shown as n0, n11.
The 11 interpolated data are n1 to n10. That is, FIG. 3 shows n0 of received data and interpolated data.
.about.n11 and directions 0 to 11 (the direction can also be said to be an angle from a predetermined reference). Although FIG. 2 is a drawing in which interpolation data is drawn in two directions, only the first two directions are shown, and the interpolation data in the subsequent eight directions are omitted for explanation. Reception data n0 is, for example, reception data 63 and its strength is 1, and reception data n11 is reception data 64 and its strength is 7.
It is. Interpolation data is calculated along a curve 92 obtained by superimposing a quadratic curve on a straight line 91 connecting received data n0 and n11. Since the received data n0 and n11 are actually measured data, the shape of the curve 92 is adopted to give weight to this data on the display unit 17 and to smoothly change the interpolated data. As for the value of the interpolated data, for example, taking the value of the sixth interpolated data n6, it is rounded off to a value slightly smaller than 5. This rounding is performed in the same way for other interpolated data values. The values of each interpolation data are shown below (the upper row shows the interpolation data number, the lower row shows the value, and the number 0 indicates the received data n0, so the received data n0
).

[Table] Including the data shown above, the data ROM 31 stores 10 pieces of interpolated data for each of 64 combinations in which the two received data serving as the reference for interpolated data are 0 to 7. Values (11 pieces of data since the received data values are also stored at the same time) are stored. In other words, the data ROM 31 contains the third
The data of the curve graph shown in the figure is stored in advance as a data table, and this data table is prepared for each weight of each of the three interpolated data n0 and n11. The signal processing main section 32 sequentially writes the received data in the direction 61 shown in FIG. 2 into the buffer memory 33, and then stores the received data in the direction 62. Then, the data table of the curve graph corresponding to the actually obtained two received data in the direction 61 and the direction 62 is read out from the data ROM 31, and the direction 61 is determined based on the read data.
The interpolated data between the direction 62 and
Output to 7. This process is performed in all directions. To explain more specifically, the received data at the same distance in the directions 61 and 62 are read out as a pair of data from a place near the center O, and from the two values, 1 of the corresponding interpolated data in the data ROM 31 is read out.
The value of the received data itself is sent to the video memory 15 via the coordinate conversion unit 14,
The display section 17 displays the information. Next, from the values of the two received data that form a pair indicating the intensity of the reflected wave at a distance one distance from the center O toward the outer periphery 81, the 0th value of the interpolated data corresponding to that value is read out and displayed. Thereafter, interpolated data is read out and displayed one after another, and eventually the received data 63 is displayed, and then the received data of the outer circumference 81 is displayed. With the above operation, direction 61
After the display of , the first value of the interpolated data is read from the data ROM 31 in the same manner as above, so that starting from the vicinity of the center O, the interpolated data 75 and 76 are displayed, and the interpolated data 73 is displayed.
The display of the interpolation data 77 continues, and the interpolation data 77 is finally displayed, and the display of the interpolation data in the direction 71 ends.
Thereafter, interpolated data in direction 72 is displayed in the same manner. By sequentially increasing the number of interpolated data read in this way, interpolated data in 10 directions is displayed, forming one section. When further clockwise angle reception data is obtained from direction 62, the same operation as above is performed in direction 62.
start from. Note that the present invention is not limited to the above-mentioned embodiments; for example, the interpolated data has been described with respect to the case where the direction is 10; It is possible to perform calculations on interpolated data in the number of directions, and the pair of 2
When calculating interpolated data from two received data, if smoother display is required, it is possible to perform calculations along the straight line 91 shown in FIG. If more weighting of received data is required, it is also possible to use a curve whose value changes more rapidly in the center, such as curve 93. Furthermore, although the case where the strength of the received data is expressed in 3 bits has been explained, it is also possible to apply the present invention to received data expressed in other numbers of bits, such as received data expressed in 4 bits with more gradations. be. The display section 17 can be similarly applied to models having a display section that is scanned from the center to the outer periphery. Effects of the Invention The PPI sonar of the present invention calculates interpolated data from received data at adjacent angles at the same distance, and uses data that extends radially to angles between the angles at which key impulses are actually emitted.
Since it is displayed together with the received data, it is possible to provide a PPI sonar that can easily display the received data over the entire circumference obtained in a short period of time. Moreover, by rewriting the data table of the curve graph stored in the data ROM, it is possible to set the weight of the interpolated data to an appropriate value, which has a great advantage in improving the smoothness of the PPI display.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the electrical configuration of an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the relationship between received data and interpolated data, and FIG. 3 is a diagram showing the values of received data and interpolated data. FIG. 13...Signal processing unit, 17...Display unit, 31...
...Data ROM, 32...Signal processing main section, 33
...Buffer memory.

Claims (1)

[Claims] 1. Key impulses are emitted at constant intervals θ in the circumferential direction, and the intensity of the reflected wave of each key impulse is sequentially A/D converted at time intervals corresponding to the distance, thereby generating n bits. Obtain multiple pieces of received data expressed by weights and display the PPI of this received data.
In PPI sonar, p and q are natural numbers, r is an integer (0≦r≦q+1)
Then, among the angles at which key impulses are emitted, adjacent ones are expressed as pθ and (p+1)θ, and the received data at the same distance at these angles is A _p ,
A _p+1 , and q between pθ and (p+1)θ
The angles divided into equal parts are θ0 (= pθ), θ1…θr…θq, θ(q
+
1) [=(p+1)θ], and if the interpolated data corresponding to the received data at the same distance as above at these angles are B ₀ , B ₁ ...B _r ...B _q , B _q+1 , then the received data A signal processing unit that calculates interpolated data B ₁ …B _r …B _q based on A _p , A p ₊₁ , and receives received data A _p , A _p+1 and interpolated data B ₁ …B _r …B _q. If the relationship between the interpolated data B _r and the angle θr is expressed as a graph of a curve of a discrete function B _r =F(θr), the signal processing unit A data table showing a graph of a curve connecting the point (θ0, B ₀ ) and the point (θ(q+1), B _q+1 ) is stored in the data ROM in advance for each n-bit weight related to the interpolated data B ₀ , B _q+1. Received data that is stored and actually obtained
The data table of the graph corresponding to A _p and A _p+1 is read out from the data ROM, and interpolated data B ₁ ...B _r ...B _q is generated based on the read data.
A PPI sonar characterized by being designed to search for.