KR20000046286A - Circuit and method for synthesizing underwater sound reflecting signals - Google Patents

Abstract

PURPOSE: A circuit for synthesizing underwater sound reflecting signals is provided to synthesize diverse reflecting signals with some program corrections by using a signal processing processor. CONSTITUTION: An analog/digital converter(U1) converts an underwater sound signal into digital data. A memory(U2) stores the output of the analog/digital converter(U1), a reflecting signal synthesis program, and various factors to be considered in synthesizing the reflecting signals. A signal processing processor(U5) synthesizes reflecting signal data in application of the time delay and weight to the output of the analog/digital converter(U1) according to the stored reflecting signal synthesis program. A digital/analog converter(U4) converts the reflecting signal data to a reflecting signal.

Description

Sonar Reflection Signal Synthesis Circuit and Synthesis Method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection signal synthesis circuit and a synthesis method capable of simulating a reflection signal by underwater sound, and more particularly, to a circuit and a method for implementing various reflection signals with one synthesizer.

A device that uses sound waves to detect the distance and position of an object is called a sona. Since the velocity of sound waves in the water is about 1500 [m] per second, the distance from the sound emission point to the object can be known by knowing the time when the emitted sound waves are reflected back to the object. In addition, it is possible to guess the approximate position or shape of the object under measurement by emitting sound waves in various directions. The application of such sonar is endless, and an example is a fish finder. This fish finder is very important equipment for fishing because it uses sonar to inform the size of fish group and the movement route of fish group. Thus, since the use of sound waves provides information on the object under test in a non-contact manner, the development of various measuring devices using sound waves is actively progressing. In addition, in the development of measurement equipment, the study of sound wave progression and reflection is essential. If there is a simulator that can predict the reflection result in the study of the sonic wave, it will greatly contribute to the study. The present invention relates to a hydroacoustic reflection signal synthesizing apparatus which will greatly contribute to such research. First, a conventional underwater reflection signal synthesis circuit will be described with reference to the block diagram of FIG.

The conventional composite circuit configuration is composed of an AD converter U1, a memory U2, an EPLD U3, and a DA converter U4 as shown in FIG.

The AD converter U1 is an analog-to-digital converter, and converts a sound wave signal converted into voltage into digital data. The memory U2 stores this digital data.

Next, an EPLD (Electrically Programmable Logic Device; U3) includes an adder, a multiplier, an offset calculator circuit, and the like.

EPLDs contain as few as hundreds to as many as tens of thousands of gates, and can be programmed to change their access. Conventionally, the EPLD is used to construct an adder, a multiplier, and an offset calculator circuit, and mainly perform mathematical calculations based on the HL (HighLight) model.

Since the HL model is virtually impossible to synthesize the reflected signals from all sides of the object when the sonar causes reflections on the object under test, only the reflected signals at a few characteristic points where the reflection is large are synthesized. To pay. To synthesize the reflected signal from all sides, we need to decompose the surface into points to synthesize the reflected signal from each point. But points don't have size and shape, so when you break a face into points, you have countless points. It is impossible to mobilize a supercomputer to synthesize the reflected signals at countless points. Therefore, the HL model sets a few characteristic points where reflections occur largely, such as HL and weighted differently, on the object and synthesizes reflection signals generated at those points. For example, if a sound wave is fired toward a fish and a reflection signal from the fish is simulated, first, HL is set in the gills, dorsal fins, caudal fins, etc. of a virtual fish. The method of using the HL model as described above is widely used for synthesizing the reflected signal of the sound waves.

On the other hand, inside the EPLD U3, an offset calculator, a multiplier, and an adder are formed to process arithmetic operations.

When simulating the reflected signal, it is configured to give weight to the input signal in consideration of the fact that the wavelength of the sound wave overlaps or attenuates between the incident wave and the reflected wave in HL, and the reflectance of the sound wave is not constant according to the shape or material of the object. to be. Moreover, it is a structure for giving the time difference (time delay) which reaches each HL of a sound wave according to the distance difference between each HL and a sonar.

The application of the time delay and the weight is processed by using a calculation circuit such as an offset calculator, a multiplier, and an adder in the EPLD U3.

Next, the DA converter U4 converts the value calculated by the preceding EPLD U3 into an analog signal. Since the output of the DA converter (U4) is an electrical signal as described above, it can be input directly to a laboratory instrument or analysis equipment without signal conversion.

The overall operation will be described based on the above configuration.

Once the sound waves are fired, they are received by the reflected signal synthesizing apparatus in which several circuits are added to the synthesis circuit of FIG. The received sound wave is converted into an electrical signal through a sound wave-electric converter, and is converted into digital data through the AD converter U1. This digital data is stored in the memory U2, and the EPLD U3 reads the digital data for sound waves stored in the memory U2 and performs calculation by the internal circuit. That is, the digital data is multiplied by a certain weight by the multiplier circuit inside the EPLD U3, and a constant time delay is given by the offset calculator circuit. The EPLD U3 then performs other necessary series of operations to produce the final reflected signal data and output it to the DA converter U4. The DA converter U4 then converts the value calculated by the EPLD U3 into an analog signal.

However, in the conventional hydroacoustic reflection signal synthesizing apparatus described above, the part performing the calculation is digital logic using EPLD. Therefore, since the values below the decimal point generated in the calculation are rounded up or down and become constant, it is impossible to accurately synthesize a reflected signal. In addition, by using hardware such as a multiplier or an offset calculator to synthesize the reflected signal, it is necessary to give a constant time delay.

The constant time delay means that there is no change in the time difference between HL (the concept of converting the distance into the sound wave's advancing time), which means that the sound wave is always incident on the object in the same direction.

Let's assume that the fish with HL set in gills, dorsal fins and caudal fins is moving, and a boat equipped with a fish finder (sonar) is moving.

When the sonar of the fish finder emits a sonar wave, the sonar wave propagates underwater in a concentric circle. When the sonar is launched from the front of the fish, the HL closest to the sonar is the HL of the gill, the next closest HL is the HL of the dorsal fin, followed by the HL of the caudal fin. But if the ship moved and the sonar was fired from the right side of the fish, the closest HL to the sonar would be the HL of the dorsal fin, followed by the HL of the gill or caudal fin. As described above, a change occurs in the distance between the sonar and HL of the dorsal fin and the sonar and gill HL as the sonar changes. Therefore, when the sonar is located in front of the fish and when it is located on the right side, the time difference between the sound waves reaching each HL is different, so that a change occurs in the time difference between the HLs.

It is necessary to consider the time difference between the HL according to the positional relationship between the sonar and the fish, that is, the change in the angle of incidence of the sonar, so that the correct reflected signal can be synthesized. However, since the time difference is fixed in the related art, the positional relationship between the fish and the sonar is inevitably constant. Therefore, only two-dimensional reflection signals can be synthesized. The reason for this problem is that the part that gives time delay in synthesizing the reflected signal in the EPLD is composed of a hardware circuit.

In addition, even if the reflected signal synthesis algorithm is slightly modified, it is inconvenient to reconfigure the hardware accordingly. To simulate the reflections from non-fish shellfish, the HL must be repositioned in the imaginary shell, thus changing the time difference between the HLs. To relocate HL, the adder, multiplier and offset calculator circuits inside the EPLD must be reconfigured. However, the reconstruction of the hardware adds cost and increases the cost burden in the development and research of sonic applications.

Accordingly, an object of the present invention is to provide a reflection signal synthesis circuit capable of synthesizing various sophisticated sonar reflection signals.

1 is a block diagram of a conventional underwater reflection signal synthesis circuit;

2 is a block diagram of a hydroacoustic reflection signal synthesis circuit according to an embodiment of the present invention.

3 is a reflection signal synthesis algorithm of the present embodiment.

4 is a flowchart of operation of the present embodiment.

* Description of the symbols for the main parts of the drawings *

U1: AD converter U2: memory

U3: EPLD U4: DA Converter

U5: DSP

In order to achieve the above object, the hydroacoustic reflection signal synthesis circuit according to the present invention includes an analog-to-digital converter for converting a hydroacoustic signal into digital data, and the reflected signal data for the digital data into a program based on a reflection signal synthesis model. A signal processing processor for synthesizing, a memory for storing the output of the analog-to-digital converter and various factors to be considered in synthesizing the reflected signal in the coral processing processor, and a digital-analog for converting the reflected signal data into a reflected signal. It is characterized by consisting of a transducer.

In addition, the hydroacoustic reflection signal synthesis method according to the present invention, the process of specifying a plurality of points that the reflection is prominent in the virtual object according to the hydroacoustic reflection signal synthesis model, and depending on the position of the virtual object and sonar A process of arranging a plurality of points in the order of a vector from a plurality of points specified in the image to a sonar, calculating a time delay between the points from the time when the sonar arrives at each point, and inputting a sonar signal. It is characterized by consisting of the process of synthesizing the reflected signal by applying the time delay and weight to the digitized sonar signal.

Hereinafter, the present invention will be described in detail with reference to the exemplary embodiment of FIG. 2.

2, there is an AD converter U1 for converting sound waves converted into electrical signals into digital data, and a digital signal processor (DSP; U5) for synthesizing a reflected signal according to a program using the digital data. There is). And a memory U2 for storing the output of the AD converter U1 and various factors necessary for synthesizing the reflected signal in the DSP U5, and converting the reflected signal data synthesized in the DSP U5 into an analog signal. There is a DA converter U4.

In the present embodiment, instead of the EPLD (U3), which uses a computation circuit to perform the calculation of the HL model, the computation is performed by software using a DSP (U5) specialized in signal processing. DSP (U5) has better signal processing function than general microprocessor and the processing speed of processor is very fast, so it can synthesize the reflected signal in real time. In addition, since only the program needs to be changed when the reflection signal synthesis algorithm is modified, various reflection signals can be synthesized with one synthesizer. However, it is also possible to use a general microprocessor if the performance of the microprocessor is improved in the future and the reflection signal can be synthesized in real time.

Next, a reflection signal synthesis algorithm is created and stored in the memory U2. In addition, the DSP U5 tables and stores various factors such as weights and time delays to be considered according to the shape and characteristics of the virtual object when synthesizing the reflected signal in the memory U2, and reads this table from the DSP U5. Program. In addition, the value of the table is configured so that the user can change it externally.

Next, Fig. 3 shows a synthesis algorithm used in synthesizing the reflected signal in this embodiment. Referring to FIG. 3, reflection signals generated by ten HLs from HL 0 to HL 9 are arranged on a time axis with respect to a sound wave signal (Ping signal). Τ _n Is the time delay of the reflected signal generated by n-HL, and the dotted line perpendicular to the time axis represents the reflected signal index. This reflection signal index is a time point at which DSP U5 newly synthesizes reflection signal data.

In this embodiment, ten HLs are set, but it is also possible to add or subtract the number of HLs without following this embodiment. By narrowing the number of HLs and the spacing of the reflected signal indexes, more sophisticated reflected signals can be synthesized.

In the case of FIG. 3, when the sonar is located in front of the virtual object (0 °), the ten HLs on the virtual object are arranged in the vector order closest to the sonar. Therefore, when the sonar is located on the right side of the virtual object, that is, at 90 °, the alignment order of HL in FIG. 3 may be changed, so that the sonar may be arranged in the order of No. 2 HL, No. 0 HL, No. 1 and No. 3 HL. The order of HL changes depending on the position of the virtual object and sonar.

As described above, if the HL is rearranged whenever the positions of the virtual object and the sonar change, a change in time difference between the HLs occurs. In other words, Τ _n The value changes each time you reorder HL. The change in time difference means that three-dimensional reflection signals can be synthesized. In this embodiment, by arranging each HL in a vector order closest to the sonar as described above, a change in the time difference between the HLs can be induced, and thus a three-dimensional reflection signal can be synthesized.

Hereinafter, the contents of the reflection signal synthesis algorithm according to the present embodiment will be described.

According to the HL model, the reflected signal at any one time is represented by the sum of several sound wave signals having different time delays. Therefore, when the reflection signal generated by one HL model is called h _i (t) and the reflection signal by multiple HL models is y (t), the relation between h _i (t) and y (t) is It can be expressed as

y (t) = h ₀ (t) + h ₁ (t) + h ₂ (t) +... (Eq. 1)

In addition, each h _i (t) is multiplied by the weight x (t) when the incident sound signal is x (t), and given the appropriate time delay is expressed as follows.

y (t) = h ₀ (t) + h ₁ (t) + h ₂ (t) +...

= W ₀ x (t- Τ ₀ ) + W ₁ x (t- Τ ₁ ) + W ₂ x (t- Τ ₂ ) +… (Eq. 2)

In the present embodiment, the above equations are processed by the program using the following arrangement in the DSP U5.

If the reflected signal array is Echo [], the sound wave signal array is Ping [], the weight array is HLTS [], and the index value considering the time delay of each HL is PingI [], the reflected signal Echo [i] at any moment is It is expressed as follows.

Echo [i] = Ping [PingI [0]] * HLTS [0] (Equation 3)

+ Ping [PingI [1]] * HLTS [1]

+ Ping [PingI [2]] * HLTS [2]

+…

The index value PingI [n] considering the time delay of each HL is calculated as follows.

PingI [n] = i- Τ _n f _s

I is a reflection signal index, Τ _n Is the time delay of the reflected signal generated by No. HL, and f _s is the sampling frequency of the DA converter U4.

Based on the above equation, the process of synthesizing the reflected signal for the acoustic wave using the present embodiment will be described in detail with reference to the flowchart of FIG.

Once the user has placed the HL on the virtual object in the program, the user can specify the position of the virtual object and the sonar (incidence angle of the sound wave) using a macro (step 10). In the order of the vector size of each HL and sonar (step 20). Τ _n (Step 30) DSP U5 Τ _n After the calculation is completed, it waits for the input of the sonar signal. (Step 40) If the sonar signal is converted into digital data through the AD converter U1 while waiting, the digital data is stored in the memory U2. During the sonic signal, the AD converter U1 converts the sonic signal converted into an electrical signal according to the sampling frequency into digital data. The DSP U5 starts synthesizing the reflected signal data since the sonar signal is input (step 50). When the reflected signal index i = 0, the reflected signal array Echo [0] is calculated (step 60). Check if the sonar signal is continuously input (step 70). If the sonar signal is continuously input, increase the reflected signal index by one (step 80). Then, the reflected signal index i = 1 is obtained. Calculate the reflected signal array Echo [1] at step 60 (step 60) and check whether the sonar signal is continuously input (step 70). (Step 80) The above process is repeated until there is no input of the sonar signal. The Echo [] calculated by the DSP U5 is converted into an analog signal through the DA converter U4.

Next, the calculation process in the DSP U5 will be described in detail. Assume that the alignment of HL in step 20 results in the same result as in FIG. 3.

Referring to FIG. 3, the synthesis of the reflected signal data at the time when the reflected signal index is 0 is related to the reflected signal generated only by HL 0. Therefore, according to equation (3)

Echo [0] = Ping [PingI [0]] * HLTS [0]; (Eq. 5)

Time delay of 0 HL Τ ₀ Is 0, so by (4)

PingI [0] = 0-0 * f _s (Equation 6)

= 0

Since the index value PingI [0] considering the time delay is 0, the DSP U5 reads Ping [0] from the sound wave signal array Ping [] stored in the memory U2, and reads HLTS [0] from the weighted array HLTS []. Read the reflected signal array Echo [] as follows.

Echo [0] = Ping [0] * HLTS [0]; (Eq. 7)

In FIG. 3, when the reflected signal index is 100, HL 0, 1, 2, 3, and 4 are related to the synthesis of the reflected signal data. Therefore, the DSP U5 calculates the index values PingI [0], PingI [1], PingI [2], PingI [3], and PingI [4] in consideration of the time delay by using Equation (4).

PingI [0] = 100- Τ ₀ f _s (8)

= 100 (∵ Τ ₀ = 0)

PingI [1] = 100- Τ ₁ * f _s

PingI [2] = 100- Τ ₂ * f _s

PingI [3] = 100- Τ ₃ * f _s

PingI [4] = 100- Τ ₄ * f _s

Τ ₁ , Τ ₂ , Τ ₃ , Τ ₄ Calculate by substituting the time delay of the reflected signal generated by HL Nos. 1 to 4 and substituting the sampling frequency of the DA converter (U4) for f _s . After the calculation, DSP U5 calculates Ping [PingI [0]], Ping [PingI [1]], Ping [PingI [2]], Ping [PingI [3] from sound wave signal array Ping [] stored in memory U2. ], Ping [PingI [4]]. DSP U5 reads HLTS [0], HLTS [1], HLTS [2], HLTS [3], and HLTS [4] from the weighted array HLTS [] table stored in memory U2. Do this.

Echo [100] = Ping [PingI [0]] * HLTS [0]; (9)

Echo [100] + = Ping [PingI [1]] * HLTS [1];

Echo [100] + = Ping [PingI [2]] * HLTS [2];

Echo [100] + = Ping [PingI [3]] * HLTS [3];

Echo [100] + = Ping [PingI [4]] * HLTS [4];

As described above, the hydroacoustic reflection signal synthesizing circuit according to the present invention is capable of synthesizing three-dimensional reflection signals as well as synthesis of various reflection signals with only a few program modifications by using a signal processing processor. Therefore, there is no need to reconfigure the hardware every time the synthesis algorithm is modified as in the prior art, resulting in cost reduction. This hydroacoustic reflection signal synthesis circuit can be applied to the development of hydroacoustic application equipment and the field of sound wave research. Especially, it can make a great contribution to simulating the reflection signal of sound waves.

Claims (3)

An analog-digital converter for converting the sonar signal into digital data; A memory for storing various factors such as a reflection signal synthesis program based on the output of the analog-to-digital converter and a reflection signal synthesis model, a time delay to be considered in the reflection signal synthesis, and weights; A signal processor for synthesizing the reflected signal data by applying a time delay and a weight to an output of the analog-to-digital converter according to the reflected signal synthesis program stored in the memory; And a digital-analog converter for converting the reflected signal data into a reflected signal. The process of designating a number of points where reflection is prominent in the virtual object according to the hydroacoustic reflection signal synthesis model, Arranging a plurality of points in order of the size of the vector from the plurality of points designated on the virtual object to the sonar device according to the position of the virtual object and the sonar device, Calculating the time delay between the points from the time when the sonar reaches each point, And a method for synthesizing the reflected signal by applying a time delay and a weight to the digitized sonar signal by the program when the sonar signal is input. The method of claim 2, The method of applying a time delay and a weight to the sonar signal, characterized in that for using the reflection method of the sonar reflection signal.