JPH0749376A - Ultrasonic algae measuring device - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain an ultrasonic algae measuring device for automatically measuring the height and density of algae that bottoms on the seabed from a remote location such as on a ship. [Structure] The reflection echo from the seabed and the reflection echo from the algae are separately subjected to propagation attenuation correction and envelope detection by two circuits, respectively, and the reflection signal from the seabed is constantly saturated to constantly reflect the reflection signal from the seabed. The seabed signal is removed from the signal, and the height and density of the algae are calculated by the arithmetic circuit based on the time width and amplitude of the extracted algae signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic algae measuring device for automatically measuring the height and amount of algae growing on the seabed by ultrasonic waves.

[0002]

2. Description of the Related Art Conventionally, there has been a method of using an ultrasonic fish finder as it is when observing the state of algae growing on the seabed from a remote place such as on a ship. This method
Ultrasonic waves are emitted toward the seabed, and reflected echoes from the seabed are received, whereby the presence or absence of algae is discriminated from the difference in the reflected echo level between the seabed and algae. However, since the algae land on the seabed, the reflected signals of the algae and the seafloor have a continuous received signal, and it is necessary to get used to extracting only the algae signal. In addition, in order to observe the condition of algae that are growing, that is, the height and density of algae, the observer extracts only the reflection echo of the alga from the received signal each time, and the reflection intensity of this reflection echo is precisely measured. Since it was calculated, the experience of the observer was required and accurate measurement was difficult.

[0003]

As described above, observation of algae using the conventional fish finder is complicated and requires experience,
In addition, there is a problem that accurate measurement is difficult.

The present invention has been made to solve the above problems, and automatically measures the presence or absence of algae, the height of algae, and the overgrowth density, and can also be used as a fish finder. It is intended to provide an ultrasonic algae measuring device.

[0005]

An ultrasonic algae measuring apparatus according to the present invention detects a reflection echo from the seabed and a reflection echo from algae by performing propagation attenuation correction and envelope detection separately. Only the algae signal is extracted based on the level difference between the reflection signal from the seabed and the reflection signal from the algae, and the height and amount of the algae are calculated based on the time width and the amplitude of the extracted algae signal.

[0006]

[Function] Since the reflection echo from the seabed and the reflection echo from the algae are different in propagation attenuation amount, if the propagation attenuation correction and the envelope detection are performed in one circuit, the accurate signal levels of the algae signal and the seabed signal can be grasped. No, which makes it difficult to separate the two signals. In the present invention, the reflection echo from the seabed and the reflection echo from the algae are separately subjected to propagation attenuation correction and envelope detection in two circuits, respectively, and the accurate signal levels of the algae signal and the seabed signal are grasped. Always saturates the reflected signal from the seabed, maximizes the level difference between the reflected signal level from the seabed and the reflected signal level from the algae, and removes the seabed signal from the continuously received reflected signals between the algae and the seabed. Then, it was decided to calculate the height and density of the algae based on the time width and amplitude of the extracted algae signal. Therefore, the height and the amount of algae can be automatically measured with high accuracy, and a wide range of seaweed beds can be measured in a short time.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an ultrasonic algae measuring device according to an embodiment of the present invention. In the figure, 1 is a wave transmitter / receiver, 2 is a transmitter, 3 is a preamplifier circuit, and 4a is a seabed. TVG circuit, 4b is an algae TVG circuit, 5a is a seabed detection circuit, 5b is an algae detection circuit, 6 is an algae signal extraction circuit, and 7 is an arithmetic circuit.

Next, the operation will be described. The transmitter / receiver 1 is excited by the transmission burst signal from the transmitter 2 and radiates ultrasonic pulses into the water. The emitted ultrasonic pulse is reflected by the algae that has bottomed on the seabed or the seabed itself, and the respective reflected echoes are again received by the wave transmitter / receiver 1 and amplified by the preamplifier 3 and output.

The received signal amplified by the preamplifier 3 has its propagation attenuation corrected by the distance in the next TVG circuit. Here, the propagation attenuation rate is reflected between the reflection echo from the seabed itself and the reflection echo from the algae. TV for submarine because of different
The attenuation correction is performed separately for the G circuit 4a and the algae TVG circuit 4b. That is, the propagation attenuation correction of the reflection echo from the seabed can be corrected using the following equation (1) as is well known, and the propagation attenuation correction of the reflection echo from the algae can be performed when the algae is uniformly bottomed. It can be corrected from above by using the following equation (2). Therefore, the respective TVG circuits 4a and 4b correct the attenuation amount using the following equations (1) and (2). A = 20.log2R + 2.alpha.R (1) B = 20.logR + 2.alpha.R (2) However, A: Attenuation of seabed reflection echo B: Algae reflection echo attenuation R: Water depth α: Absorption attenuation constant The seabed signal and the algae signal, which have been propagation-attenuated by the seabed TVG circuit 4a and the algae TVG circuit 4b, are subjected to envelope detection by the next seabed detection circuit 5a and algae detection circuit 5b, respectively. , Is input to the algae signal extraction circuit 6, where only the algae signal is extracted. Hereinafter, extraction of the algae signal in the algae signal extraction circuit 6 will be described in detail.

As a result of the propagation attenuation correction of the seabed signal due to the difference in distance in the seabed TVG circuit 4a, the reflected signal level becomes independent of the water depth and depends only on the bottom sediment. Similarly, as for the algae signal, the propagation attenuation correction is performed by the algae TVG circuit 4a due to the difference in distance. As a result, the reflected signal level becomes independent of the water depth and depends only on the algae density. The difference in the reflection level due to the difference in the bottom material is, as described in "Ultrasonic Technical Handbook" by Nikkan Kogyo Shimbun, the reflection intensity is -5 when the bottom material is (rock).
dB, (sand) -8 dB, (mud) -12 dB
Is known to be. In addition, the difference in the reflection level due to the difference in the density of algae growth was as follows: Kitou Kan: “Understanding the algae abundance using ultrasonic equipment” in 1986.
In that case, the reflection intensity is -33.3 dB, and in the case of (coarse)-
It is known to be 52 dB. Therefore, the difference in the reflection level between the seabed and the algae is the smallest, and the difference in the reflection level differs by 20 dB or more even when the sediment is (mud) and the algae (dense). Only can be extracted.

That is, assuming that the output of the TVG circuit 4a for the seabed is Ts1, Ts1 = 20 · logV ₁ − (SL + ER + G ₀ ) = 2.
0 · logV ₁ −K (3) (where SL is the transmission level, ER is the receiving sensitivity, G _{0 is the} preamplification circuit gain), and the output of this TVG circuit 4a for the seabed Is saturated when the sediment is (mud), substituting the seabed signal level V ₁ = 10, Ts1 = -12 into the equation K = 20 · logV ₁ −Ts1 (4),
We get K = 32. Therefore, the seabed signal level V ₁ is (mud)
When saturated with algae signal level V ₂ , the algae TVG
If the output of the circuit 4b is √n · Ts2, then 20 · logV ₂ = √n · Ts2 + K (5), so that 0.1 ≦ V ₂ ≦ 0.87 (6) Saturating the submarine signal level V ₁ regardless of quality
The output Ts1 of the TVG circuit 4a for the seabed having this signal level (V ₁ ) does not include the algae signal (V ₂ ), and only the algae signal can be extracted.

FIG. 2 is a diagram showing an output waveform from each circuit shown in FIG. 1. (a) is an output waveform from the seabed detection circuit 5a, which is just saturated even when the bottom sediment is (mud). The algae signal is removed at this level. (B) is an output waveform from the algae detection circuit 5b,
Due to the difference in the density of algae growth (dense to coarse), the range of the above formula (6) is obtained. Therefore, from the output waveform (b) to the output waveform (a)
The waveform after time t ₂ is removed by using, and the output waveform (c) of only the algae signal can be easily extracted from the algae signal extraction circuit 6.

In the next arithmetic circuit 7, the output waveform (c) from the algae signal extraction circuit 6 is input, and its time width (t ₂ -t ₁ )
And the signal level V is detected, and H = C · (t ₂ −t ₁ ) ... (7) (where C is the speed of sound in water) √n · Ts ₂ = 20 · logV ₂ −K ... (8 ), The algal height (H) and the algal density √n · Ts2 are calculated.

[0014]

As described above, the ultrasonic algae measuring apparatus of the present invention uses separate propagation attenuation correction TVG circuits for the seabed signal and the algae signal, respectively, and saturates the seabed signal to saturate the seabed signal. A wide range of seaweed beds can be automatically measured by extracting only the algae signal and calculating the algae height and overgrowth density using the arithmetic circuit based on the time width and amplitude of the algae signal. There is an effect that it can be carried out accurately and in a short time.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an output waveform of each circuit shown in FIG.

[Explanation of symbols]

 1 Transducer 2 Transmitter 3 Preamplifier circuit 4a Submarine TVG circuit 4b Algae TVG circuit 5a Submarine detection circuit 5b Algae detection circuit 6 Algae signal extraction circuit 7 Arithmetic circuit

Claims (1)

[Claims] 1. An ultrasonic pulse into water having two circuits (one of which is tentatively referred to as a seabed circuit and the other one being tentatively called algae circuit) having a circuit composed of a TVG circuit and a detection circuit. Means for transmitting the received reflected signal to the above circuit, and in the above-mentioned submarine circuit, A = 20.log2R + 2.alpha.R.
···················································································································· B = 20 · logR + 2αR ··· in the algae circuit
-Means for correcting the propagation attenuation by the formula (2) and adjusting the output level so that the difference in the algae overgrowth becomes the difference in the output level (however, A: attenuation of the seabed reflection echo B : Attenuation of algae reflection echo R: Water depth α: Absorption attenuation constant), using the output signal of the seabed circuit, the portion of the output signal of the algae circuit, which is the reflection signal from the seabed, is removed to reflect from the algae. A means for extracting only the signal portion, a calculation means for calculating the height of the algae to be measured by the temporal length of the reflection signal from the algae, and a vegetation density based on the reflection signal level were provided. Ultrasonic algae measuring device characterized by.