JPS6390786A - Extremely fine signal reception system for guidance and assistance system for berthing - Google Patents

Abstract

PURPOSE:To automatically cope with variation in echo level after device installation by monitoring the level of a receive signal all the time and adjusting it to the best level, and monitoring whether a received pulse is outputted or not and varying a threshold level automatically so that a received pulse can securely be acquired. CONSTITUTION:A main control means is equipped with a level deciding circuit 2, a continuity deciding means 3, and a gain control signal generating circuit 4, and a threshold level varying means is equipped with a received pulse presence/absence deciding circuit 6, a continuity deciding means 7, and a threshold voltage generating circuit 8. A variable gain amplifier 1 amplifies the received signal with a gain specified by a gain control signal, so automatic constant adjustment is possible. Further, the gain control means monitors whether the level of the received signal is within a proper range or not all the time, so not only initial adjustment at the time of the installation of the system, but also subsequent variations are sufficiently coped with. A signal leading-out circuit 5 is set automatically to a level specified by the threshold level varying means and this setting is not varied in response to accidental variation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention measures the speed, etc. of a ship attempting to berth using ultrasonic waves, notifies the ship, and provides guidance assistance so that the ship can appropriately decelerate and berth. This paper relates to a weak signal reception method for an ultrasonic measurement system in a system.

[Prior Art] In this type of berthing guidance support system, the berthing speed of a ship is generally measured by detecting the distance at a predetermined sampling period using an ultrasonic range finder and measuring the change in this distance over time. ing.

The ultrasonic range finder emits ultrasonic pulses from a quay toward a ship, receives reflected waves that are reflected by the ship's hull, and calculates the distance from the round trip time and the speed of sound. In this case, the time required for round trip is as follows: The transmission of the transmitted wave is the trigger to open the gate, the reception of the reflected wave is the trigger to close the gate, and while the gate is open, the reference clock pulse is output from the clock circuit. It is obtained by counting the number of times and calculating the time based on the counted value.

By the way, in this type of gate, in order to prevent malfunctions due to noise, it is necessary to separate received waves from noise. Therefore, a signal extraction circuit consisting of a comparator or the like is provided to extract only received waves exceeding a certain threshold level as received pulses.

To extract the received pulse from the reflected wave whose level has attenuated,
It is necessary to amplify the received wave so that its level exceeds the threshold level of the signal extraction circuit, and it is also necessary to set the threshold level of the signal extraction circuit in accordance with this amplification.

In this case, if the amplification degree is increased too much, it will rise to the noise level and cause erroneous measurements, so the amplification degree must be set within an optimal range.

Conventional berthing guidance assistance systems are configured to amplify received waves using a variable gain amplifier equipped with a manual gain adjuster. Gain adjustment was performed by receiving reflected waves at the location where the guidance assistance system was installed and manually adjusting a gain adjuster so that the received waves were at an optimal level.

On the other hand, the threshold level is set by adjusting the output voltage of the threshold voltage generation circuit in accordance with the output of the variable gain amplifier.

[Problems to be Solved by the Invention] However, in the conventional gain adjustment and threshold level setting described above, since they are adjusted when the device is installed and then fixed as they are, the echo level may fluctuate afterwards. In some cases, there is a drawback that erroneous measurements may occur. Further, since the adjustment work is performed by a person, it is inevitable that the adjustment will vary depending on the operator.

Furthermore, if the echo level decreases and one reflected wave cannot be received, it is difficult to make adjustments each time.

As a result, there is a problem in that continuous measurement becomes impossible.

The present invention has been made to solve the above-mentioned problems, and its purpose is to constantly monitor the level of the received signal and automatically adjust the gain to the optimum level. The threshold level can be dynamically changed to ensure that received pulses are captured by constantly monitoring whether or not the received pulse is being output, and it automatically responds to changes in the knee level after the device is installed. To provide a weak signal reception method for a berthing guidance assistance system that can be used in a berthing guidance assistance system, which does not cause continuous measurement failure and does not cause individual differences in adjustment.

By the way, the echo level often fluctuates, so
If you adjust it each time, it may have the opposite effect and increase the fluctuation range of the next reflected wave. Furthermore, if the threshold level is set every time the received wave level accidentally drops, there is a risk of picking up noise when the echo level becomes high.

Another object of the present invention is to provide a weak signal reception method for a berthing guidance assistance system that can detect that fluctuations are occurring either high or low and make appropriate adjustments.

[Means for Solving the Problems] The present invention provides an ultrasonic measurement system in a system that measures the speed, etc. of a ship attempting to berth using ultrasonic waves, notifies the ship, and assists the ship to berth at an appropriate speed. In order to achieve the above objective in the weak signal reception system of Determine whether the level is within the appropriate range, higher than the appropriate range, or lower, and determine the r high level.
or gain control means for outputting a gain control signal that changes the gain of the variable gain amplifier when the variable gain amplifier is at a "low level".

and a signal extraction circuit that outputs a signal exceeding a threshold level among the amplified received signals to a subsequent stage as a received pulse.

The present invention is characterized in that it comprises a threshold level changing means for changing the threshold level of the signal extraction circuit when the received pulses are not continuously outputted from the signal extraction circuit a preset number of times.

For example, as shown in FIG. 2, the gain control means determines whether the level of the received signal is within an appropriate range, is higher than the appropriate range, or is lower than the appropriate range, and determines the level status corresponding to each. A level determination circuit 2 that outputs a signal, and when either a level status signal of "r high level" or "low level" is output from the level determination circuit 2 a predetermined number of times in succession, a level change instruction signal is generated. and a gain control signal generation circuit 4 that generates a gain control signal for specifying a change in the gain of the variable gain amplifier 1 in response to a level change instruction signal from the continuity determination means 3. Prepared and configured.

Further, the threshold level changing means is as follows.

For example, as shown in FIG. 2, after the transmission wave is transmitted and before the next transmission, it is determined whether or not a reception pulse is output from the signal extraction circuit 5, and a status signal indicating the presence or absence of the reception pulse is output. a circuit 6 for determining the presence or absence of a received pulse to output; a continuity determining means 7 for monitoring the status signal and outputting a threshold level change instruction signal when the received pulse is not output for a preset number of consecutive times; Upon receiving the level change instruction signal, vs.

and a threshold voltage generating circuit 8 which outputs a corresponding threshold voltage to the signal extraction circuit 5.

[Operation] In the problem solving means of the present invention configured as described above, the variable gain amplifier amplifies the received signal with a gain specified by the gain control signal. Therefore, unlike manual adjustment, which has large individual differences.

Automatic constant adjustment is possible.

In addition, since the gain control means constantly monitors whether the level of the received signal is within the appropriate range, it is possible to adequately deal with not only the initial adjustment when installing the berthing guidance support system, but also any subsequent fluctuations. be able to. Therefore, even if a received signal at a level that can act as a gate trigger cannot be obtained because the level of the reflected wave is low, the gain is automatically changed to obtain a received signal at a triggerable level. Furthermore, when the gain of the amplifier is large and the noise level is high, the gain is lowered to prevent erroneous reception due to noise.

On the other hand, the signal extraction circuit is automatically set to a specified level by the threshold level changing means. This setting is performed by detecting that the received pulse is not continuously output a preset number of times from the signal extraction circuit. Therefore, it is not changed by random fluctuations.

This threshold level is changed when the echo level of the received wave does not reach the threshold level, so the change is performed exclusively by lowering the threshold level.

This change is particularly effective when the echo level of the received wave is still low even if the gain of the variable gain amplifier is set to the maximum.

[Example] Embodiments of the present invention will be described with reference to the drawings.

<Configuration of Embodiment> FIG. 3 shows the configuration of an embodiment of the weak signal receiving system of the present invention.

The receiving system of the embodiment shown in the figure includes a variable gain amplifier 1,
and a level determination circuit 2 that determines whether the level of the output voltage of the amplifier l is within a proper range.

a gain control signal generation circuit 4 that forms a gain control signal according to the level change instruction signal and sends it to the variable gain amplifier 1;
a signal extraction circuit 5; a received pulse presence/absence determination circuit 6 for detecting whether or not a received pulse is output from the signal extraction circuit 5; The device includes a threshold voltage generation circuit 8 and a microcomputer 9.

The level determination circuit 2 includes, for example, a window comparator, and compares the output signal level of the variable gain amplifier 1 with reference to a preset upper limit value and lower limit value. As a result of the comparison, if the signal level is between the upper limit and lower limit, it is "appropriate", and if it exceeds the upper limit, r
Level status signals PROPER and HIG respectively correspond to "high level" and "low level" if below the lower limit value.
)I, outputs LOW.

In this embodiment, the gain m control signal generation circuit 4 generates a gain control signal that changes the amplification gain of the variable gain amplifier stepwise in a range of one to a plurality of stages. is changed by ±1 step according to instructions from the microcomputer 9.

The signal extraction circuit 5 is composed of a comparator, and compares the output voltage of the variable gain amplifier 1 with a threshold voltage, and outputs a received pulse when the output voltage exceeds the threshold voltage.

The received pulse presence/absence determination circuit 6 is configured to determine whether or not a pulse has been input within a certain period of time from when the gate is opened, and output a status signal indicating the presence or absence of a received pulse.

The threshold voltage generation circuit 8 is comprised of a variable voltage DC power supply, and in this embodiment, is sent to the comparator of the signal extraction circuit 5 as a threshold voltage. This threshold voltage generation circuit 8 can output one to a plurality of different voltages in response to instructions from continuity determining means 7, which will be described later.

The microcomputer 9 functions as a continuity determining means 3 that determines whether or not the inappropriate level continues a certain number of times, and as a continuity determining means 7 that determines that the received pulse is not outputted a certain number of times in succession. This microcomputer 9 includes a microprocessor 90, a program memory 91 that stores programs for the processor 90, an input/output board 92, and an internal bus 93 that connects these.
It is composed of: Note that this microcomputer 9 does not need to be provided exclusively for the continuity determining means 3 and 7, and one used for other purposes of the system can be used.

<Operations of the Embodiment> The weak signal receiving system of this embodiment configured as described above operates as follows.

First, as shown in FIG. 4, a transmitted wave T is transmitted at a cycle longer than the round trip time required for ultrasonic waves, and one reflected wave R is received after the round trip time has elapsed after the transmission of the transmitted wave.

Since this received wave R is attenuated, the variable gain amplifier 1
is amplified. As a result, as shown in Figure 4, if the peak value is between the upper and lower limits of the appropriate range,
It is considered to be a normal received wave.

A level determination circuit 2 determines whether the received wave is at an appropriate level. As a result of the comparison, the level judgment circuit 2
If the signal level is between the upper and lower limits, it is "appropriate"
PROPER1 means HIGH means "high level" if it exceeds the upper limit value, and "HIGH" means "high level" if it goes below the lower limit value.
Each corresponding level status signal of LOW, meaning "low level", is output.

Furthermore, the continuity determining means 3 causes the level status signal HIGH or LO- of either "r high level" or "low level" to be continuously output from the level determining circuit a preset number of times (two times in this embodiment). The continuity determining means 3 monitors whether or not the level change instruction signal is output when either one is output a predetermined number of times in succession. This action will be explained with reference to the flowchart in FIG.

First, the microprocessor 90 of the continuity determining means 3
reading the received signal level status signal from the level determination circuit 2 via the input/output port 92 (step l);
Then, the microprocessor 90 checks whether this status signal is PROPER or not, and checks whether it is within the appropriate range (step 2). If it is within the appropriate range, the process returns to step 1. If it is inappropriate, proceed to step 3.

In step 3, it is determined whether the received signal level is higher or lower than the appropriate range based on whether the status signal is RIG)I or LOW. Here, as shown by ■ in Figure 5,
microprocessor 90
It is checked whether or not it was at the "r high level" at the time of the previous sampling (step 4). If it is not "high level", the process returns to step l. If the previous time was also "high level", proceed to step 5.

Note that the microprocessor 90 stores the previous status signal in a memory (not shown), and after checking the previous status signal, updates it to the current status signal.

In step 5, a signal is sent to the gain control signal generation circuit 4 via the internal bus 93 and the input/output port 92, setting the gain level to -1 and instructing the gain to be lowered by one step.

If the level is lower than the lower limit in step 3 above, the microprocessor 90 checks whether the level was "low" during the previous sampling (step 6); if it is not "low level", the microprocessor 90 continues as is. Return to step l. If the previous time was also “low level”, go to step 7.
Proceed to.

In step 7, a signal is sent to the gain control signal generation circuit 4 via the internal bus 93 and the input/output port 92, setting the gain level to +1 and instructing to increase the gain by one step.

In response to this, the gain control signal generating circuit 4 generates a gain control signal for specifying a change in the gain of the variable gain amplifier 1.

Even if the gain of the variable gain amplifier l is lowered in this way, it still remains as shown by ■ in FIG.

If the level of the received waveform is higher than the appropriate range, the same operation as described above is repeated until it becomes as shown by ■ in the figure.

Note that in this embodiment, when the received signal of "r high level" and the received signal of "low level" appear alternately, neither state occurs consecutively twice, so the gain of the variable gain amplifier is not changed.

Next, the received wave output from the variable gain amplifier l is
The signal is input to the signal extraction circuit 5 and the threshold is input.

It is compared with a threshold voltage output from the field voltage generation circuit 8. As a result, if the input signal is greater than the threshold voltage, the eight received waves are extracted as received pulses and sent to a subsequent gate (not shown).

On the other hand, as shown in FIG. 7, when the input signal is lower than the threshold voltage, this input received wave is.

The output presence/absence determination circuit 6, which is not output as a signal, monitors whether or not a received pulse is output after the transmission of the transmission wave T and before the transmission of the next transmission wave T, and outputs a status signal indicating the presence or absence of the reception pulse. In this embodiment, as a status signal indicating the presence or absence of a received pulse, a signal that is sent to the microprocessor 90 constituting the continuity determining means 7 is a signal that is at a high level when a received pulse is output, and is at a low level when a received pulse is not output. Output.

As shown in FIG. 8, the microprocessor 90 performs a continuity determination using J! II. Read the output pulse presence/absence status signal (step 1) and check the presence or absence of the status signal (step 2). If the signal is at a high level, the received pulse is being output, and the microprocessor 90 performs step 1. Return to On the other hand, as shown in FIG. 7, if the signal is at a low level, the process proceeds to step 3.

In step 3, it is checked whether the status signal was hot during the previous sampling. If the status signal was present last time, the process directly returns to step l. On the other hand, if the status signal was hot last time as well, proceed to step 4, that is,
In this embodiment, the threshold level is changed when the status signal is hot twice in a row.

The microprocessor 90 stores the previous status signal in a memory (not shown), and after checking the previous status signal, updates it to the current status signal.

In step 4, a signal instructing to lower the threshold voltage by one step is sent to the threshold voltage generation circuit 8 via the internal bus 93 and the input/output port 92.

In response to this, the threshold voltage generation circuit 8 sends a threshold voltage lower than that at the previous sampling to the signal extraction circuit 5.

Even if the threshold voltage of the signal extraction circuit 5 is lowered in this way, if the level of the received waveform is lower than the threshold level, as shown by ■ in FIG.
The same operation as described above is repeated until it becomes as shown by ■ in the figure.

<Modification of Embodiment> In the above embodiment, the received signal of "high level" or "
Although the configuration is such that the gain of the variable gain amplifier is changed when any of the received signals of "low level" occurs twice in a row, the number of consecutive times may be three or more times.

Similarly, when the input signal falls below the threshold level,
Although the configuration is such that the threshold level is changed when the status signal heat is output twice in a row, the number of consecutive times may be three or more times.

Further, in the above embodiment, the continuity determining means 3 and 7 are configured by microcomputers, but the level determining circuit 2
．． Gain control signal generation circuit 4. Output pulse presence/absence determination circuit 6
etc., can also be configured using a microcomputer.

[Effects of the Invention] As explained above, the present invention can constantly monitor the level of the received signal and automatically adjust it to the optimum level, and can also constantly monitor whether or not the received pulse is being output. It can monitor and automatically change the threshold level to ensure that the received pulse is captured, and it can automatically respond to changes in echo level after the device is installed, making continuous measurements impossible. Moreover, it has the effect of allowing adjustments to be made without causing individual differences in adjustment.

Further, the present invention has the advantage that it is possible to detect whether the peak level fluctuation of the received wave is biased toward either the high or low side, and to make appropriate adjustments.

Therefore, according to the present invention, it is possible to realize a weak signal reception method for a berthing guidance assistance system that is unlikely to cause erroneous measurements.

[Brief explanation of the drawing]

is a block diagram showing the configuration of an embodiment of the present invention, FIGS. 4 and 5 are waveform diagrams for explaining the gain control action of this embodiment, and FIG. 6 is a waveform diagram for explaining the gain control action of this embodiment. Flowchart for. FIG. 7 is a waveform diagram for explaining the effect of changing the threshold level in this embodiment, and FIG. 8 is a flowchart for explaining the effect of changing the threshold level in this embodiment. l...Variable gain amplifier 2...Level judgment circuit 3...J! ! Continuity determination means...Gain control signal generation circuit 5...Signal extraction circuit 6...Received pulse presence/absence discrimination circuit 7...Continuity determination circuit 8...Threshold voltage generation circuit 90...Micro Processor 91...program memory 92...input/output boat 93...internal bus

Claims (3)

[Claims] (1) In the weak signal reception method of the ultrasonic measurement system in a system that measures the speed etc. of a vessel attempting to berth using ultrasonic waves and notifies the vessel and provides guidance assistance so that it can berth at an appropriate speed, , a variable gain amplifier that amplifies with a gain specified by a gain control signal, and determines whether the level of the received signal is within an appropriate range, higher than the appropriate range, or lower, and determines whether the level of the received signal is "high level".
or a gain control means for outputting a gain control signal that changes the gain of the variable gain amplifier when the level is "low", and the amplified received signal that exceeds the threshold level is used as a received pulse. The signal extraction circuit is configured to include a signal extraction circuit for outputting to a subsequent stage, and a threshold level changing means for changing the threshold level of the signal extraction circuit when the received pulses are not continuously outputted from the signal extraction circuit a preset number of times. A weak signal reception method for a berthing guidance assistance system featuring: (2) The gain control means is a level determination circuit that determines whether the level of the received signal is within an appropriate range, higher than the appropriate range, or lower, and outputs a level status signal corresponding to each. and a continuity determining means for outputting a level change instruction signal when either a "high level" or "low level" level status signal is continuously output from the level determining circuit a predetermined number of times; and a gain control signal generating circuit for forming a gain control signal for specifying a change in the gain of the variable gain amplifier in response to a level change instruction signal from the continuity determining means. Weak signal reception method for berthing guidance assistance system. (3) The threshold level changing means determines whether or not a received pulse is output from the signal extraction circuit after transmitting the transmitted wave and before the next transmission, and outputs a status signal indicating the presence or absence of the received pulse. a circuit for determining the presence or absence of a received pulse; continuity determining means for monitoring the status signal and outputting a threshold level change instruction signal when the received pulse is not output for a preset number of consecutive times; and receiving the threshold level change instruction signal. A weak signal receiving system for a berthing guidance assistance system according to claim 1 or 2, further comprising a threshold voltage generation circuit for outputting a corresponding threshold voltage to the signal extraction circuit.