JPH0239754B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention detects the received signal from a specific detected object among the received signals obtained by detecting the reflected detection of the detected object using wave pulses such as ultrasonic waves and radio waves. The present invention relates to a reflection detection device that magnifies and displays received signals in a predetermined range based on a reference and also displays the distance to the detected object.

[Conventional technology]

Such reflective detection devices include radars and fish finders. For example, a conventional fish finder has a configuration as shown in FIG.

In the figure, a transmitter 2 receives an output from a transmission pulse generator 1 and generates ultrasonic pulses, which are input to a transducer 4 via a transmission/reception switching circuit 3, and the ultrasonic waves are emitted. The ultrasonic wave is reflected by an object to be detected such as a school of fish, reaches the transducer 4 after the propagation time in the medium, becomes an electric signal, and enters the receiver 5 via the transmission/reception switching circuit 3. The signal amplified and detected by the receiver 5 becomes a bright/dark signal input to the display 6. The display device 6 separately receives an input from the transmission pulse generator 1 as a timing pulse, uses it as a display time axis, and displays the distance to the object to be detected. Fish finders often first measure the depth to the seabed, and then enlarge the display scale to display the depth so that it fills the entire width of the display.

[Problem to be solved by the invention]

Enlarged display operation is essential for schools of so-called bottom-hungry fish that are concentrated on the seabed, but in conventional fish finders, the signal output received by the transducer 4 is first transmitted through the transmission line and then through the reverberant signal. , reflections from mid-layer plankton and fish schools, bottom-based fish schools near the seabed, and seafloor reflectivity are continuous, and noise and interference from other ships' emitted waves are likely to be added, making seabed depth measurements inaccurate. There were other inconveniences such as instability, the relationship between the enlarged scale of the display 6 and the display range did not match, and an unexpected error occurred in the seabed depth value, making it impractical.

Furthermore, in the case of radar, the same inconvenience as in the case of the above-mentioned fish finder occurs when detecting the coastline and targets close to the coastline.

As a means to solve such instability in seabed detection, a type of AGC is installed to control the amplification degree of the receiver based on the output of the receiver that amplifies the detected received signal. Japanese Patent Publication No. 39747/1974 discloses a means for detecting only one pulse signal at a time, and using this pulse as a signal corresponding to a seabed signal as a coefficient for the depth value. .

However, with the above method, the received signal is lost due to the output signal from the receiver being reflected from other objects to be detected. In order to perform enlarged display based on the specific object to be detected, there is a problem of how to configure it to be practical.

[Means to solve the problem]

The present invention emits the above-mentioned wave-based transmission pulse into a medium, and receives the reflected waves from the detected object.The present invention then detects the amplitude of a plurality of detected objects at a long distance from among the received signals obtained by emitting the wave-based transmission pulses into a medium and receiving the reflected waves from the detected objects. The distance value to the specific detected object is measured using the detection signal obtained by detecting the signal of the detected object that can obtain a large reflected wave, that is, the signal of the specific detected object, and based on this detection signal, the above-mentioned In a reflection detection device that displays a received signal in an enlarged display using a specific detected object as a reference, the received signal is amplified and detected in order to display the above-mentioned enlarged signal. branching signal means for obtaining a branched signal by branching from an input point of the receiver or a suitable position of the receiver, and controlling the amplification degree of the control amplifier circuit with the signal generated by the control signal generator, so that the above-mentioned waves are generated in the medium. a time sensitivity control means for obtaining an output obtained by applying the above-mentioned branch signal to a time sensitivity control circuit configured to perform time sensitivity control to compensate for the amount of attenuation received; The above attenuation compensation signal is applied to an amplifier circuit that performs automatic gain adjustment so that only one pulse signal is generated during one period of the transmission timing pulse of the above transmission pulse, and the obtained output is used as a gain adjustment output. automatic gain adjustment means for obtaining a signal; and waveform shaping for obtaining an output as a shaped signal by applying the above-mentioned adjusted output signal to a shaping circuit for shaping each signal waveform in the above-mentioned gain-adjusted output signal into a rectangular shape. means, removing signals whose transmission lines, reverberations and time widths do not reach standard values from the above-mentioned shaped signals, and
A shaped pulse having a width detection circuit that generates an output only when a signal with an equal time elapsed from the above transmission timing pulse is received repeatedly is obtained by applying the above shaped signal to a test circuit. A part of the above test output signal is supplied to a test means for obtaining the output as a test output signal, and a signal hold circuit for storing time difference information between the one pulse signal and the transmission timing pulse. The above problem is solved by providing: a time difference information storage means for storing information; and a display means for displaying the distance value based on the time difference information and enlarging the output signal of the receiver. It was designed so that it could be obtained.

〔Example〕

FIG. 2 shows a block diagram of an embodiment of the present invention.
The same parts as in FIG. 1 are indicated by the same symbols.

In the figure, a pulse of ultrasonic frequency is generated from a transmitter 2 in accordance with an output timing pulse of a transmission pulse generator 1, and the ultrasonic wave is emitted from a transducer 4 via a transmission/reception switching circuit 3.

When the reflected waves from the object to be detected, the seabed, etc. are detected by the transducer 4, they become electrical signals, pass through the transmission/reception switching circuit 3, are amplified and detected by the receiver 5, and are provided as input signals to the display 6.

A portion of the input signal of the receiver 5 is input to a sensitivity time control circuit 7 (also referred to as STC), where the signal is compensated for propagation losses in the medium, and its output is input to an automatic gain adjustment amplifier 8. .

The automatic gain adjustment amplifier 8 automatically adjusts the gain so that only one output pulse from the shaped pulse inspection circuit 10 (described later) is generated in one cycle of the timing pulse from the pulse generator 1. The output of the automatic gain adjustment amplifier 8 is detected and shaped by a received signal pulse shaping circuit 9, and the output is further guided to a shaped pulse inspection circuit 10.

The shaped pulse test circuit eliminates input pulses whose time widths do not reach a standard value, and generates an output only when pulses having the same elapsed time from the transmitted signal wave are repeatedly received a plurality of times.

When the output pulse of the shaped pulse test circuit 10 becomes only one within the transmission pulse period as a result of the above-mentioned automatic gain adjustment amplification, the automatic gain adjustment amplifier 8 fixes the gain at that position, and the shaped pulse test circuit 10
A part of the output is input to the signal hold circuit 11 and stored as time difference information with the timing pulse, and the seabed depth is displayed numerically, and is further provided to the display 6 as bottom lock information.

Next, the circuit operation of the present invention will be explained in detail.

In FIG. 2, the input line of the sensitivity time control amplifier 7 is branch-connected from the input signal circuit of the receiver 5, but if the input line of the sensitivity time control amplifier 7 satisfies the condition that the signal current is not saturated, receiver 5
There is no problem even if it is introduced in the middle or branched from the output side.

Control amplifier circuit 71 in sensitivity time control amplifier 7
is controlled by a control signal from the control signal generator 72, and its gain increases over time starting from the timing pulse received from the transmission pulse generator 1. Its time gain characteristic is such that the emitted wave is in the medium. This is to compensate for the amount of attenuation TL received, and to obtain a received signal whose magnitude is proportional to the reflection ratio of the object, regardless of the distance to the reflecting object. In other words, if the distance to the reflecting object is l, and the length at which the medium gives a propagation attenuation of 1 dB is x, then the gain is controlled to increase over time at the rate of TL = 20log ₁₀ (2l/x) (dB). be done.

As a result of the above, as shown in FIG. 3B, the output of the sensitivity time control amplifier 7 is such that when the reflected signals are arranged on the time axis, the seafloor reflected signal is the largest.

The output of the sensitivity time control amplifier 7 is led to an automatic gain adjustment amplifier 8. The automatic gain adjustment amplifier 8 receives output pulses from a shaped pulse inspection circuit 10 (described later) in a variable gain signal generation circuit 81, and if the number of pulses received during one period of the transmission timing pulse is one, the same gain is maintained. . When there is no received pulse, the variable gain signal generation circuit 81 generates a gain increase signal u.
Upon receiving this signal, the gain selection circuit 82 switches the analog switch to increase the gain by one step.
The gain of the AGC circuit 83 is increased by one step (for example,
6dB) increase.

If the number of pulses received at the input of the variable gain signal generation circuit 81 is two or more, it emits a gain reduction signal D,
In response to this, the gain selection circuit 82 switches the analog switch to the gain decreasing side by one step to decrease the gain of the AGC circuit by one step (for example, 6 dB).

The output of the automatic gain adjustment amplifier 8 is input to a received signal pulse shaping circuit 9. First, the amplifier circuit 91,
Next, the received signals detected through the rectifier circuit 92 are subjected to transmission line and dereverberation removal and waveform shaping in a waveform shaping circuit 93.

The above-mentioned waveform-shaped signal pulse is input to the shaped pulse inspection circuit 10, and the interference removal circuit 101 selects from among the received pulses only those pulses that have been continuously received multiple times at positions with the same time difference with the timing pulse. , interference signals from equipment on other ships,
Width detection circuit 1 removes irregular pulses such as noise.
At 02, pulses that do not reach the reference value time width are removed.

The output pulse of this shaped pulse inspection circuit 10 is 1
If the reception sensitivity is such that only one pulse can be received, that single pulse is nothing but a signal reflected from the ocean floor.
This is because the wave reflectance of the ocean floor is the highest, and the propagation loss in the medium due to distance has been corrected by the sensitivity time control amplifier 7 as described above.

The situation of automatic production described above will be explained with reference to a measurement example explanatory diagram in FIG. In the figure, the horizontal axis is time, and the left end is the time t=0 of the transmission timing pulse. FIG. 3A shows the received wave envelope when the received reflected wave signal is in a non-saturated state. The received wave a is the transmission line, b is the reverberation, c is the close-range fish school, f
is a large school of long-distance fish, g is the ocean floor, h is noise, and i is the second echo on the ocean floor.

FIG. 3B shows a received wave whose propagation loss in the medium has been corrected using the output waveform of the sensitivity time control amplifier 7. FIG. 3C illustrates a situation in which the detection and shaping are performed. FIG. 3D shows the output waveform of the shaped pulse inspection circuit, from which the transmission line, reverberation, relatively weak reflected signal, and narrow waveform example h of time width have been removed. In this state, since the number of pulses is two or more, the automatic gain adjustment amplifier 8 is controlled to decrease the gain by one step.

At the stage shown in FIG. 3F, the number of output pulses was reduced to one.
Therefore, the gain adjustment is completed and the remaining pulse is only the seabed reflection signal, so the seafloor depth can now be calculated.

Although not shown as an example in FIG. 3, if the gain adjustment becomes excessive and the received signal level drops and no shaped pulse is output, the variable gain signal generating circuit 81 outputs the signal u, so automatic gain adjustment is performed. Amplifier 8 is controlled to increase the gain by one step.

When the control is completed in the state shown in FIG. 3F, the output of the shaped pulse inspection circuit 10 is received by the signal hold circuit 11 and stored as information on the elapsed time from the transmitted pulse, and is further sent to the seabed depth display circuit 12 to display the depth numerically. However, a submarine signal (bottom lock signal) is sent to the display 6.

Since there is a signal hold circuit 11, even if there is a disturbance in the receiving state and the submarine signal becomes temporarily silent, the display circuit 6 will maintain the seabed state immediately before the disturbance, and the measurement will continue. There will be no interruptions.

FIG. 4 shows a specific circuit example of an embodiment of the gain selection circuit 82 and AGC circuit 83 in the automatic gain adjustment amplifier 8. When the gain selection circuit 82 receives a signal from the variable gain signal generation circuit 81, one analog switch in the analog switch group 821 operates, and one of the resistors in the resistor group 822 is grounded.
Since bridging loss is given to the AGC circuit 83, the gain is adjusted to increase or decrease in steps.

Although the above explanation has been made regarding an example of reflection detection in water using ultrasonic waves, similar effects can be obtained in a reflection detection device that uses radio waves or other waves to detect reflections in the air, underground, or elsewhere.

According to the present invention, it is possible to provide a device having the following various features.

First, separate from the system that provides the display signal from the receiver 5 to the display 6, there is a system that branches off the received signal, and this branched system receives the seabed detection pulse, that is, the specific object to be detected. Since the detection means for obtaining the detection signal of can do.

In other words, in the case of a fish finder, for example, for objects that move up and down at high speeds such as squid and tuna, or minute objects such as plankton, the detection depth changes each time it is transmitted, so the same A point in time can only be obtained once.

In the case of reflection detection using radio waves such as radar,
For example, buoys for purse seining or longline fishing are similarly available only once per transmission.

For this reason, it disappears in the process of noise removal processing such as correlation processing, and the thing that is being detected is missed. However, according to the present invention, as described above, the detection control Since it is possible to display a faithful detection signal without being affected, such detection losses due to missed detection are eliminated.

Furthermore, at actual detection sites, interference signals include the signals transmitted by other ships, and noise signals include the screw sounds of other ships, which provide important information such as the positional relationship with other ships. For example, when operating in a foggy environment, it provides information on the approach of other ships.

According to the present invention, even with such interference signals, the interference state/noise state can be displayed as is on the display 6, which has the advantage of being able to grasp the distance from other ships, etc. There is a reason.

Second, the time difference information between the obtained seabed detection pulse and the transmission timing pulse is transferred to the signal hold circuit 1.
1, and a disturbance protection means for supplying bottom lock information, which serves as a standard for enlarged display, to the display 6, that is, information for the display standard, via the signal hold circuit 11. Because of this, even if there is a temporary disturbance in the detection signal, the seabed depth and bottom lock display can be stably performed.

In the case of radar, for example, a coast lock display based on the coastline is performed instead of a bottom lock display.

In other words, in the case of fishing boats, turning, temporary backtracking,
In places where underwater bubbles are generated by screws, such as when sailing on the wake of another ship, this bubble layer blocks the passage of ultrasonic waves, causing the above-mentioned disturbance. In this case, the direction of the ultrasonic beam shifts diagonally every moment due to the shaking of the ship.
Because the depth of the seabed becomes unstable, the detected seabed detection pulse disappears, causing the depth display and bottom lock display to collapse.

However, according to the present invention, the previously obtained and stored seabed depth can be used and displayed.
It has the advantage of providing a display that is free from display disturbances caused by such disturbances.

In the case of radar, similar situations occur due to weather conditions such as snow, beam deviation due to sudden turning of the ship, etc., but can be dealt with in the same way.

Thirdly, the control amplifier circuit 71 is added to the control signal generator 72 in the configuration of the STC portion of the detection means described above.
Since the control signal means for controlling the STC by the control signal from the STC is provided, it is possible to easily obtain ideal time sensitivity characteristics of the STC.

In other words, in conventional STC, the time constant circuit consisting of a resistor and capacitor provided in the input circuit of the amplifier is the main method used to obtain time sensitivity characteristics, but the amplification characteristics of the amplifier etc. are involved in a complex manner. Therefore, this method has the disadvantage that it is difficult to obtain ideal time sensitivity characteristics as shown in the above equation.

However, in the present invention, since the control amplifier circuit 71 is configured as a control signal means that is controlled by the control signal from the control signal generator 72, the control signal generator 7
Since it is only necessary to variously change only the activation signal No. 2, the present invention has the advantage that ideal time sensitivity characteristics can be easily obtained compared to conventional ones.

Fourthly, in the pulse inspection using the above detection means, first, the pulse shaping circuit 9 shapes the pulse, and then the shaped pulse inspection circuit 10 analyzes the transmission line signal, the reverberation signal, the relatively weak reflected signal, and the time width. A test means is provided to generate a remaining pulse after removing the narrow signal, and output a detection pulse only when the same elapsed time from transmission is repeated multiple times. The circuit configuration can be simplified and stable detection can be performed.

In other words, since the input signal is first shaped and then detected, each received signal is converted into a clear rectangular signal for detection processing.
When removing reverberation and signals with a narrow time width, there is no ambiguity in the time length, and the subsequent processing circuit can be of a simple configuration.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional fish finding device, Fig. 2 is a block diagram of a fish finding device of the present invention, Fig. 3 is an explanatory diagram of an example of the received signal processing operation in the device of Fig. 2, and Fig. 4 is a block diagram of a conventional fish finding device. The figure is a specific example circuit diagram of an automatic gain adjustment amplifier. 1... Transmission pulse generator, 2... Transmitter, 3...
... Transmission/reception switching circuit, 4... Transducer/receiver, 5... Receiver, 6... Display, 7... Sensitivity time control amplifier,
8... Automatic gain adjustment amplifier, 9... Received signal pulse shaping circuit, 10... Shaped pulse inspection circuit, 11
... Signal hold circuit, 12 ... Seabed depth display circuit, 71 ... Control amplifier circuit, 72 ... Control signal generator, 81 ... Variable gain signal generation circuit, 82 ... Gain selection circuit, 83 ... AGC circuit, 91... Amplifier circuit, 92... Rectifier circuit, 93... Waveform shaping circuit, 101... Interference wave removal circuit, 102... Width detection circuit, 821... Analog switch group, 822
...Resistor group.

Claims (1)

[Claims] 1. The amplitude of a signal that is far away from a plurality of objects to be detected from among the received signals obtained by emitting a wave-based transmission pulse into a medium and receiving reflected waves from the objects to be detected. The distance value to the specific detected object is measured based on the detection signal obtained by detecting the signal of the detected object (hereinafter referred to as the specific detected object) from which a large reflected wave is obtained, and the distance value to the specific detected object is measured. A reflection detection device that displays the received signal in an enlarged display using the specific detected object as a reference, the method comprising: a) displaying the received signal with a non-saturation condition for the enlarged display; branching signal means for branching from an input point of a receiver for amplifying and detecting the received signal or from an appropriate position of the receiver to obtain a branch signal; b. controlling the amplification degree of the control amplifier circuit with the signal generated by the control signal generator; time sensitivity control means for applying the branch signal to a time sensitivity control circuit configured to perform time sensitivity control to compensate for the amount of attenuation that the wave receives in the medium, and obtaining an output obtained as an attenuation compensation signal; The attenuation compensation signal is obtained by applying the attenuation compensation signal to an amplifier circuit that performs automatic gain adjustment such that the gain is controlled by the test output signal of the transmission pulse and generates only one pulse signal during one period of the transmission timing pulse of the transmission pulse. automatic gain adjustment means for obtaining the output as a gain adjustment output signal; a waveform shaping means for obtaining a signal; e. removing from the shaped signal signals of transmission lines, reverberations, and signals whose time width does not reach a standard value, and repeating the signal with the same time elapsed from the transmission timing pulse a plurality of times; testing means for applying the shaped signal to a shaped pulse testing circuit having a width detection circuit for generating an output only when a return signal is received, and obtaining the obtained output as a testing output signal; a time difference information storage means for storing the time difference information by supplying a part of the output of the shaped pulse inspection circuit to a signal hold circuit for storing time difference information between the pulse signal and the transmission timing pulse; g. A reflection detection device characterized by comprising display means for displaying the distance value based on the distance value and for displaying the output signal of the receiver in an enlarged manner.