JPH08101271A - Unit body/group body signal detector and various apparatus employing it - Google Patents

Abstract

PURPOSE: To enhance accuracy in the measurement of the body length of a fish, for example, by reducing possibility of erroneously recognizing a signal reflected from a group body target as a signal reflected from a unit body target. CONSTITUTION: Reflection signals, subjected to propagation attenuation correction by a TVG circuit 4, are subjected to envelope detection by an envelope detection circuit 5 and a signal having duration of envelope close to that of a transmitted pulse is detected by a unit body signal detection circuit 6. A phase comparison circuit 7 compares a reflection signal outputted from the TVG circuit 4 with a reference clock for phase comparison thus determining the phase thereof. A phase variation amount detection circuit 8 detects only such reflection signal as the phase thus determined is scarcely varied in the reflection signal. A unit body signal extraction circuit 9 extracts only such reflection signal as detected by both the unit body signal detection circuit 6 and the phase variation amount detection circuit 8. A TS calculation circuit 10 determines the strength of a reflection signal extracted by the unit body signal extraction circuit 9 based on the amplitude thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single / group signal detecting apparatus for extracting only a reflected signal from a single or group target among reflected waves from a target, and further using this, a single signal reflection intensity (TS). The present invention relates to a single reflection intensity detection device that obtains a value and is used for fish length measurement and the like.

[0002]

2. Description of the Related Art FIG. 5 shows a structure of a single-body reflection intensity detecting device according to a conventional example. The device shown in this figure includes a clock generation circuit 1, a transmission circuit 2, a transceiver 3, and a T
It is composed of a VG circuit 4, an envelope detection circuit 5, a single signal detection circuit 6 and a TS calculation circuit 10.

The clock generation circuit 1 generates a burst signal for transmission and supplies it to the transmission circuit 2. The transmission circuit 2 power-amplifies the transmission burst signal supplied from the clock generation circuit 1 and supplies it to the transceiver 3. The transmitter / receiver 3 transmits ultrasonic waves into water according to the transmission burst signal supplied from the transmission circuit 2. When a target (fish or the like) is present in the surroundings, the reflected wave from the target is received by the wave transmitter / receiver 3 and is acoustically / electrically converted. The TVG circuit 4 performs propagation attenuation correction for a single target on the reflected wave converted into the electric signal by the wave transmitter / receiver 3, that is, the reflected signal. That is, the reflected signal is amplified by the characteristic represented by the following equation. By this propagation attenuation correction, the level of the reflection signal from the target having the same reflection intensity becomes constant regardless of the water depth R.

[0004]

[Equation 1] In FIG. 6A, the reflected signals T1 to T3, which have been subjected to the propagation attenuation correction by the TVG circuit 4, are shown together with their envelopes.

The envelope detection circuit 5 envelope-detects the reflected signal whose propagation attenuation is corrected by the TVG circuit 4, and extracts the envelope. That is, as shown in FIG. 6B, envelope information is extracted for each of the reflection signals T1 to T3 shown in FIG.

The single signal detection circuit 6 is an envelope detection circuit 5
The reflected signals T1 to T based on the envelope detected by
The time width P1 to P3 for which 3 continues is obtained. The single signal detection circuit 6 compares the obtained time widths P1 to P3 with the transmission pulse width P supplied as information from the clock generation circuit 1. The single signal detection circuit 6 treats only the reflection signal satisfying the following expression as the reflection signal from the single target, and the other reflection signals are from the group target, that is, a target which looks as a single body as a result of a plurality of single targets gathering Treated as a reflected signal.

[0007]

[Equation 2] Therefore, in the case of the example shown in FIG.
Is detected as a reflection signal from a single target by a relatively time width Pi as shown in FIG.
Are only small reflected signals, ie T1 and T2.
In other words, if the time width Pi is sufficiently close to the transmission wave pulse width P, the obtained reflection signal can be regarded as a reflection signal from a single target. Single signal detection circuit 6
Detects a single target from such a viewpoint.

The TS value calculation circuit 10 provided at the subsequent stage of the single signal detection circuit 6 has a TS value for the reflection signals T1 and T2 which are reflected signals from the single target by the single signal detection circuit 6, that is, single signal strength. Calculate TSi. At that time, the TS calculation circuit 10 detects the maximum amplitudes V1 and V2 of the reflected signals T1 and T2, and performs the calculation based on the following equation. As a result, TS1 and TS2 are obtained only for the reflected signals T1 and T2 shown in FIG. 6 (c). The obtained TS values TS1 and TS2 are used for fish length measurement and the like.

[0009]

(Equation 3)

[0010]

However, in the conventional apparatus having such a structure, the reflected signal from the group target is actually regarded as the reflected signal from the single target, and as a result, the accurate TS value is obtained. Also, there is a problem that the distribution cannot be obtained.
That is, as shown in FIGS. 6B and 6C, the reflection signal T2, which can be regarded as a reflection signal from a plurality of single targets which are actually close to each other, has a time width P2 of a transmission signal pulse. Only because it is close to the width P, it is regarded as a reflection signal from a single target. As a result, as shown in FIG. 7, in the histogram of the TS values, in addition to the true distribution obtained by the single target, the distribution for the colony target that is mistakenly regarded as the reflection signal from the single target also appears. I will end up. This causes a significant deterioration in measurement accuracy when measuring fish length and the like.

The present invention has been made to solve the above-mentioned problems, and takes out only a single target or a group target by newly using phase information instead of the time width of a transmission signal. It is possible to improve the accuracy of fish length measurement. Another object of the present invention is to further improve the accuracy by using phase information in addition to the time width information used conventionally.

[0012]

In order to achieve such an object, a single signal detecting device according to the present invention comprises means for detecting the phase of a reflected signal and an amount of time change of the phase within an individual reflected signal. Is smaller than a predetermined value, and a first detecting means for detecting only a reflection signal whose phase time change amount is smaller than a predetermined value as a reflection signal from a single target. .

The single signal detecting apparatus according to the present invention further detects a time width of the reflected signal and only a reflected signal in which the detected time width falls within a predetermined range as a reflected signal from the single target. Second detection means,
Detection result synthesis means for detecting only a reflection signal detected as a reflection signal from the single target by both the first detection means and the second detection means, as a reflection signal from the single target.

The single reflection intensity detecting apparatus according to the present invention comprises a single signal detecting apparatus according to the present invention, means for detecting the amplitude of a reflection signal, and reflection detected as a reflection signal from a single target by the detection result integrating means. For signals only,
And means for obtaining the reflection intensity based on the amplitude.

The group signal detecting device according to the present invention comprises means for detecting the phase of the reflected signal, means for judging whether or not the time change amount of the phase within the individual reflected signal is smaller than a predetermined value, and First detection means for detecting only a reflection signal whose time change amount is larger than a predetermined value as a reflection signal from the group target.

The group signal detecting apparatus according to the present invention further includes means for detecting the time width of the reflected signal and only the reflected signal whose detected time width does not fall within the predetermined range as the reflected signal from the group target. And a detection result synthesis unit that detects only a reflection signal detected as a reflection signal from the group target by both the first detection unit and the second detection unit as a reflection signal from the group target. Is characterized by.

[0017]

In the single signal detecting device according to the present invention, first, the phase of the reflected signal is detected. Next, the reflection signal from the single target is detected by paying attention to how the phase within the individual reflection signal changes with time. That is, when the phase hardly changes with time inside a certain reflection signal, this reflection signal can be regarded as a reflection signal from a single target, and conversely, the phase within the reflection signal changes with time by a predetermined amount or more. In this case, the reflected signal can be regarded as a signal obtained by superposing the reflected signals from a plurality of single targets, that is, the reflected signal from the group target. Therefore, in the present invention, only the reflection signal whose phase time change amount is smaller than a predetermined value is detected as the reflection signal from the single target.
In this way, since the single target is detected using the phase information of the reflected signal, in the present invention,
The probability of erroneously recognizing a group target as a single target is smaller than that in single target detection using the time width information of the reflected signal.

In the single signal detecting apparatus according to the present invention, in addition to the single target detection focused on the time variation of the phase inside the reflected signal, the single target detection focused on the time width of the reflected signal is performed. . That is, the time width in which the reflection signal lasts is detected, and the reflection signal in which the detected time width falls within the predetermined range is detected as the reflection signal from the single target. The detection results obtained by these two methods (the method based on the time change amount of the phase and the method based on the time width) are integrated by the detection result integrating means, and both of them are detected as the reflection signal from the single target. The reflected signal is detected as the reflected signal from the single target. Thus, by combining the two types of methods, it is possible to further reduce the probability of misidentifying a colony target as a single target.

In the single-piece reflection intensity detection device according to the present invention, the reflection signal is obtained based on the amplitude of the reflection signal from the single target detected by the single-signal detection device according to the present invention. The reflection intensity thus obtained, that is, the TS value, can be used for detecting the size of each single target (the fish length when the target is a fish). As described above, in the single-signal detection device according to the present invention, the probability of misidentifying a group target as a single target is reduced. Therefore, in the single-reflection intensity detection device according to the present invention, the TS value can be obtained more accurately. it can.

In the group signal detecting device according to the present invention, in the same manner as the single signal detecting device according to the present invention,
The reflected signal from the colony target is detected. That is, in the present invention, it is possible to distinguish the reflection signal from the single target and the reflection signal from the group target based on the time variation of the phase in the individual reflection signal and the time width of the reflection signal. . Therefore, in an application that uses the reflected signal from the group target, the accuracy of the processing can be improved by using the group signal detection device according to the present invention.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. The same components as those of the conventional example shown in FIGS. 5 to 7 are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 shows the configuration of a single-body reflection intensity detecting device according to an embodiment of the present invention. The device shown in this figure has a configuration in which a phase comparison circuit 7, a phase change amount detection circuit 8 and a single signal extraction circuit 9 are further added to the conventional device shown in FIG.

Clock generation circuit 1 to single signal detection circuit 6
The TS calculation circuit 10 has the same function as the conventional example shown in FIG. Therefore, for example, in the state where the reflected signal as shown in FIG. 2A is obtained by the TVG circuit 4, the output of the envelope detection circuit 5 becomes the output shown in FIG. The output of 6 is shown in FIG.
The output is shown in.

The first feature of this embodiment is that the phase comparison circuit 7 and the phase change amount detection circuit 8 are used to detect a single target by paying attention to the phase change amount inside each reflection signal. The second feature of the present embodiment is that the single signal detection circuit 6 combines the single target detection result and the phase change amount detection circuit 8 single target detection result by the single signal extraction circuit 9, and the TS calculation circuit is based on the result. 10 is that the TS value TSi is calculated.

First, the phase comparison circuit 7 receives the phase comparison reference clock supplied from the clock generation circuit 1 and synchronized with the transmission burst signal. This phase comparison reference clock therefore represents a predetermined reference phase. The phase comparison circuit 7 compares the phase of each reflection signal T1 to T4 output from the TVG circuit 4 with a reference clock for phase comparison. At that time, the reflection signals T1 and T2 detected as the reflection signals from the single target by the single signal detection circuit 6
If the phase comparison is performed only for the frequency, the frequency of the phase comparison calculation is reduced.

The phase comparison result thus obtained is
The contents are shown in FIG. That is, for the reflection signal T1 from the single target, the phase comparison result shows a substantially constant phase difference θ1, while the reflection signal T1 from the group target is actually present, the single signal detection circuit 6
With respect to the reflection signal T2 which is erroneously recognized as a single target, the phase comparison result changes with time within the reflection signal T2.

This is because the reflected signal T2 is the same as the reflected signal from the single target A shown in FIG. 3 (aA).
FIG. 3 shows a reflection signal from the single target B shown in FIG.
This is due to the result of superposed reception as shown in (a). Assuming that the reflection signal T2 shown in FIG. 3A is obtained from the TVG circuit 4, the reflection signal T2
Of the portions related to only the target A or B, the phase comparison result is θ corresponding to the target A or B, respectively.
Whereas A or θB, the phase difference θA, B is the amplitude and position of the reflection signal from each target A and B at the portion where the reflection signal from target A and the reflection signal from target B overlap. It is a function of the phase difference (phase comparison result). That is, the value is represented by the following formula.

[0028]

[Equation 4] The phase change amount detection circuit 8 detects the amount of phase change in each reflection signal based on the output of the phase comparison circuit 7, that is, the phase comparison result shown in FIG. That is, like the reflected signal T1, the reflected signal T
1 Regarding a reflection signal with a small change in the phase difference inside, information indicating that the amount of change in the phase difference is small is output to the single signal extraction circuit 9, and the reflection signal T2 like the reflection signal T2 is output.
2 Regarding the reflection signal having a large amount of phase change inside, information indicating that the amount of phase change is large is supplied to the single signal extraction circuit 9 (FIG. 2 (e)).

The single signal extraction circuit 9 integrates the output of the single signal detection circuit 6 and the output of the phase change amount detection circuit 8 to obtain a reflection signal that can be regarded as a reflection signal from the single target, that is, a reflection signal. Extract only T1.
More specifically, only the reflection signal T1 in which the time width Pi of the envelope detected by the envelope detection circuit 5 is sufficiently close to the transmission pulse width P and the amount of phase change in the inside thereof is sufficiently small is extracted (FIG. 2 ( f)). The TS calculation circuit 10 calculates the TS value TS1 only for the reflection signal T1 extracted by the single signal extraction circuit 9.

Therefore, according to this embodiment, as shown in FIG. 4, in the histogram of the TS value TSi, the reflection signal from the group target is actually regarded as the reflection signal from the single target. Since the resulting distribution (“histogram of overestimation”) does not occur at the output of the TS calculation circuit 10, the TS value TSi calculated by the TS calculation circuit 10 and the fish length measurement accuracy calculated using this TS value TSi Is significantly improved compared to the conventional one.

Although the above description is for the purpose of extracting the reflection signal from the single target,
On the contrary, the present invention may be applied to the purpose of extracting the reflection signal from the colony target. Further, the present invention does not need to be limited to the use of calculating the TS value TSi using the reflected signal from the extracted single target or the group target.
Further, although the above description has shown the use of transmitting and receiving ultrasonic waves in water, the present invention is not limited to such use.

[0032]

As described above, according to the single signal detecting device of the present invention, the reflected signal from the single target is detected by paying attention to the time change amount of the phase inside each individual reflected signal. Therefore, as compared with the case where the reflection signal from the single target is detected by paying attention only to the time width in which the reflection signal lasts, it becomes possible to accurately extract only the reflection signal from the single target. At that time, if the single target detection focusing on the time width of the reflected signal is also executed and the single target is taken out by integrating the detection results of both methods, the probability of misidentifying the colony target as the single target is lower. And the detection performance is higher.

According to the single-piece reflection intensity detection device of the present invention, the single-signal detection device of the present invention is used to detect the reflection signal from the single target, and the reflection intensity is obtained based on its amplitude. The single-body reflection intensity (TS) value can be obtained more accurately, and further, the fish length and the like can be obtained more accurately.

According to the group signal detecting apparatus of the present invention,
In order to detect the reflected signal from the group target by the same method as the single signal detection device according to the present invention,
The reflected signal from the group target can be detected more accurately, that is, a signal that was conventionally misidentified as a single target can be detected as the group target.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing waveforms at various points in this embodiment;
(A)-(f) is a figure which shows the waveform of (a)-(f) in FIG.

3A and 3B are diagrams showing a relationship between a reflection signal from a group target and a phase comparison output, where (aA) shows a reflection signal from a single target A, (aB) shows a reflection signal from a single target B, and 10A shows a reflection signal obtained as a result of superimposing the reflection signal of (aA) and the reflection signal of (aB), and (d) shows a result of phase comparison of the reflection signal of (a) with a reference clock for phase comparison. It is a figure.

FIG. 4 is a histogram showing the effect of this embodiment.

FIG. 5 is a block diagram showing a configuration of an apparatus according to a conventional example.

FIG. 6 is a diagram showing a waveform of each part in this conventional example,
(A)-(c) is a figure which shows the waveform of (a)-(c) in FIG.

FIG. 7 is a histogram showing the problems of this conventional example.

[Explanation of symbols]

 1 Clock generation circuit 2 Transmission circuit 3 Transducer 4 TVG circuit 5 Envelope detection circuit 6 Single signal detection circuit 7 Phase comparison circuit 8 Phase change amount detection circuit 9 Single signal extraction circuit 10 TS calculation circuit T1 to T4 Reflected signal P1 to P4 Time width of reflected signal θ1 to θ3, θA, θB, θA, B Phase of reflected signal V1, V2, VA, VB Maximum amplitude of reflected signal

Claims (5)

[Claims] 1. A means for detecting a phase of a reflected signal, a means for judging whether or not a time change amount of the phase inside each individual reflected signal is smaller than a predetermined value, and a time change amount of the phase is smaller than a predetermined value. A single signal detection device comprising: a first detection unit that detects only a reflection signal as a reflection signal from a single target. 2. The single signal detection device according to claim 1, wherein a unit for detecting a time width of the reflected signal and only a reflected signal whose detected time width falls within a predetermined range are detected as a reflected signal from the single target. And a detection result synthesis means for detecting only a reflection signal detected as a reflection signal from the single target by both the first detection means and the second detection means, as a reflection signal from the single target. A single signal detection device characterized by: 3. The single signal detection device according to claim 1 or 2, a means for detecting an amplitude of a reflected signal, and an amplitude of only a reflected signal detected as a reflected signal from a single target by the detection result integrating means. A unit for detecting a single reflection intensity, comprising: 4. A means for detecting the phase of the reflected signal, a means for judging whether or not the time variation of the phase within the individual reflected signal is smaller than a predetermined value, and a time variation of the phase being larger than the predetermined value. A first detection means for detecting only the reflection signal as a reflection signal from the group target, and a group signal detection device comprising: 5. The group signal detecting device according to claim 4, wherein the means for detecting the time width of the reflected signal and the only reflected signal whose detected time width does not fall within a predetermined range are reflected signals from the group target. Second detection means for detecting, and total detection result means for detecting only the reflection signal detected as the reflection signal from the group target by both the first detection means and the second detection means, as the reflection signal from the group target. A group signal detection device characterized by the above.