JPS6015143Y2 - Aircraft noise determination device - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a device for determining whether noise received by a microphone during noise measurement is aircraft noise.

Aircraft noise is generally measured by measuring the maximum level of noise at a predetermined point for each flight.

In this case, it is necessary to determine whether the noise received by the microphone is aircraft noise to be measured, and if it is other than aircraft noise, it must be excluded from the measurement, and only if it is aircraft noise, it must be measured.

This determination may be made by placing a supervisor at each measurement point, but this is not practical if the measurement period is a long period of time, regardless of day or night.

For this reason, devices that can automatically identify and determine aircraft noise have been proposed.

This device was developed based on the fact that the level of aircraft noise is often significantly higher than other noises (factory noise, traffic noise, etc.).

That is, only when the noise received by the microphone exceeds a preset level, the noise is regarded as aircraft noise and the measurement state is entered.

Noises other than aircraft noise usually do not exceed the set level, so these are naturally excluded and not measured.

Therefore, the predetermined setting level is naturally set in consideration of the noise level emitted by the aircraft, that is, in response to the aircraft noise level.

However, in the above determination means, if noise occurs during measurement, such as noise caused by the passing of a large vehicle near the measurement point, or the sound of a siren near the measurement point, the setting level is set in accordance with the aircraft noise level. In some cases, noise that should not be measured may be mistakenly recognized as aircraft noise.

This idea eliminates as much as possible the misjudgment that could occur in the past,
This enables more accurate aircraft noise determination.

In other words, the time period during which aircraft noise exceeds a preset level (hereinafter referred to as duration time), which is set to a certain level higher than other noises (such as large vehicle passing noise or siren sounds near the measurement point), as described above. This method takes advantage of the fact that the length ( ) is relatively long.

In other words, the noise is aircraft noise only if the noise exceeds a set level set corresponding to the aircraft noise level and its duration exceeds a preset time corresponding to the duration of aircraft noise. The judgment is made by considering that.

Therefore, even if the noise level is high and was incorrectly considered to be aircraft noise in the past, it can be excluded from the measurement target because the duration is shorter than that of aircraft noise, increasing the accuracy of aircraft noise determination. .

An embodiment of the present invention will be described below with reference to the drawings.

In Fig. 1, 1 is a sound level meter, and microphone IA
The noise received by the amplifier IB and the A-characteristic correction circuit IC
, an effective value rectifier circuit ID, and a logarithmic compression circuit 1E, it becomes a logarithmically compressed output, that is, an analog output (DC leveled output).

This is JIS C1502 ordinary sound level meter or JIS C1
It functions as a sound level meter as specified in 50 Scenic Sound Level Meter.
A standard pointer-type sound level meter has a meter connected to this output.

Incidentally, the analog output is compared in the analog comparison circuit 2 with a setting level preset in the level setting circuit 3.

As this set level, for example, a comparison voltage constructed from a reference voltage generator and a resistive voltage divider and calibrated to a voltage corresponding to the noise level is used.

Note that since the level of aircraft noise and background noise differs depending on the measurement point, it is desirable to make the setting level variable, and generally a configuration that allows variable setting in 5 dB steps is sufficient.

That is, the set level is set in accordance with aircraft noise.

Now, in the analog comparator circuit 2, when the noise received by the microphone, specifically the analog output, exceeds a set level, the output of the comparator circuit 2 is applied to the duration detection circuit 4.

Note that the output waveform of the comparator circuit 2 is shown by A in FIG.

This duration detection circuit 4 includes, for example, a pulse generation circuit 4.
It is composed of an A1 gate circuit 4B and a digital counter 4C.

That is, as mentioned above, when the set level is exceeded, the comparator circuit 2 is reversed and the gate circuit 4B is opened, and as a result, the pulses of a constant period (generally 1 second period) generated by the pulse generating circuit 4A are The digital counter 4C counts and the duration is detected.

Note that B in FIG. 2 shows the waveform of the gate circuit 4B, and C shows the output waveform of the gate circuit 4B.

Reference numeral 5 denotes a digital comparison circuit, which compares the set duration time set in advance by the duration setting circuit 6 and the duration detected by the duration detection circuit 4.

When the set duration time is exceeded, the output of the digital comparator circuit 5 is inverted.

This is an output that determines that the noise received by the microphone is aircraft noise because it exceeds the set level and the time (duration) for which it exceeds the set level is longer than the preset duration.

Note that D in FIG. 2 shows the output waveform of the comparator circuit 5.

The output of the digital comparison circuit 5 is connected to one input of the AND gate circuit 7, and when it is determined that the noise is from an aircraft, the terminal of the AND gate circuit 7 is kept at a high voltage logic level.

In addition, D in FIG. 2 is the output waveform of the comparator circuit 5, and E is the AND
The output waveform of the gate circuit 7 is shown.

On the other hand, if the aircraft takes off and the noise level falls below the set level, the analog comparison circuit 2 will be inverted, so
Using the inverted output at this time, a monostable multivibrator 8 generates a trigger pulse, which passes through an AND gate circuit 7 and is held by a maximum level holding circuit 9, which converts the maximum noise level generated by the aircraft at that time from A to D. It can be converted into a digital quantity by the device 10 and displayed or recorded.

The present invention was originally developed by focusing on temporal changes in the noise level of a noise source.

Therefore, the present invention can be similarly applied to the determination of noise such as automobile running noise when traffic volume is low and noise that causes temporal changes in noise level similar to those of aircraft, such as railway noise. It is.

As described above, the present invention was developed by focusing on the fact that the noise level of aircraft noise is relatively high, and the noise duration above a certain level is long.

In other words, the present invention includes a comparison circuit that compares an analog output corresponding to the output of a sound level meter and a set level preset in a level setting circuit, and a comparison circuit that compares an analog output corresponding to the output of a sound level meter with a set level preset in a level setting circuit, and a comparison circuit that compares an analog output corresponding to the output of a sound level meter with a set level set in advance by a level setting circuit, and a comparison circuit that compares an analog output corresponding to the output of a sound level meter with a set level set in advance by a level setting circuit, and a comparison circuit that compares an analog output corresponding to the output of a sound level meter with a set level set in advance by a level setting circuit, and a comparison circuit that compares an analog output corresponding to the output of a sound level meter and a set level preset in a level setting circuit, and a comparison circuit that compares the analog output corresponding to the output of a sound level meter and a set level set in advance in a level setting circuit, and a comparison circuit that compares the analog output corresponding to the output of the sound level meter and a set level set in advance in a level setting circuit, and a comparison circuit that compares the analog output corresponding to the output of a sound level meter and a set level set in advance in a level setting circuit. A comparison circuit that compares the analog output with a set time preset by a setting circuit, and determines aircraft noise only when the analog output exceeds the set level and the duration of the exceeded time exceeds the set time. This significantly increases the reliability of aircraft noise determination.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is a time chart for explaining one embodiment of the present invention. 1: Sound level meter, 2: Comparison circuit, 3-level setting circuit, 4:
Continuation time detection circuit, 5: Comparison circuit, 6: Continuation time setting circuit.

Claims (1)

[Scope of Claim for Utility Model Registration] (a) A sound level meter that outputs a noise output signal corresponding to the noise received by a microphone; (b) A level of a predetermined value corresponding to the noise level that should be determined as aircraft noise. a level setting circuit that outputs a setting signal; (C) a first circuit that sends out a first detection output when the signal level of the noise output signal of the sound level meter exceeds the signal level of the level setting signal of the level setting circuit; a comparison circuit; (d) counting clock pulses from when the first detection output is obtained until the first detection output is no longer obtained, and transmitting the count result as a duration detection output; a duration detection circuit; (e) a duration setting circuit that outputs a duration setting signal having a predetermined value corresponding to a duration to be determined as aircraft noise; and (f) a duration detection output of the duration detection circuit. a second comparison circuit that sends out a second detection output when the count content exceeds the predetermined value of the duration setting signal of the duration setting circuit; An aircraft noise determination device that transmits signals as signals.