JP2897382B2 - Echo prevention method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] For example, regarding an echo prevention system used in a municipal disaster management radio system, the purpose of the present invention is to suppress the occurrence of echo and make it easier to hear the contents of a loudspeaker broadcast. And a plurality of outdoor slave stations with loudspeakers for loudspeakers connected to the station via a radio line and distributed so as to cover the entire service area, and the outdoor slave station receives information from the master station. In an information transmission system for broadcasting and transmitting to the residents, at a predetermined point P in an area where an echo occurs when the outdoor child station broadcasts simultaneously,
A control device having a measuring means for measuring the volume of the loudspeaker broadcast by the surrounding outdoor child station and a volume control signal generating means for generating a volume control signal using the measurement result is provided. Volume control means for controlling the volume of the loudspeaker broadcast by a predetermined amount in response to the applied volume control signal is provided, and when the control device detects the occurrence of an echo, a predetermined one of the outdoor slave stations in the vicinity is provided. A volume control signal is transmitted to the outdoor slave station so that the volume of the loudspeaker broadcasting is reduced by a predetermined amount.

[Industrial applications]

The present invention relates to an echo prevention system used in, for example, a municipal disaster management radio system.

The municipal radio system for disaster prevention administration is a system that is set up by municipalities with the primary purpose of using it for operations related to local disaster prevention, emergency rescue, and disaster recovery.

This system includes a fixed system, a mobile system, and a telemeter system, or a combination thereof. The fixed system is a system that transmits information to residents through a 60 MHz band wireless line from a master station installed in the local government.
An outdoor loudspeaker system that transmits information by transmitting loudspeakers over a wide area from outdoor child stations installed in various places within the municipality,
There is a door-to-door reception system in which information is transmitted on a door-to-door basis by a door-to-door reception station installed in each home.

The mobile system is a simplex system performed between a base station and a mobile station provided at the headquarters of each municipality, and between mobile stations.

Here, in the case of the outdoor loudspeaker system, the loudspeaker broadcasting of the same content is sequentially delayed from a plurality of outdoor child stations depending on the area, and is heard by the inhabitants of the area (echo is generated), making it difficult to hear the contents of the loudspeaker broadcasting May be.

Therefore, it is necessary to suppress the occurrence of echo to make the contents of the loudspeaker broadcast easy to hear.

[Conventional technology]

FIG. 4 is a block diagram of a conventional example, and FIG. 5 is an operation explanatory diagram of FIG.

The operation of FIG. 4 for transmitting information using the outdoor loudspeaker system will be described below with reference to FIG. Note that the solid line in FIG. 5 indicates a range in which loudspeakers from outdoor private stations A and B can be heard.

First, a master station (not shown) sends information to be transmitted to an outdoor slave station using a transmission signal having a designated frequency and a power of 10 W in the 60 MHz band.

The outdoor slave stations A and B receive signals from the master station by the receivers 11 and 15 and extract the above information, and then amplify the signals by the loudspeaker amplifiers 12 and 16, for example, loudspeaker broadcasting with a driving power of 30 to 40W. Speaker 1
Driving 3 and 14 to loudspeak and broadcast this information to local residents.

Here, the distance between the house and the outdoor slave station varies depending on the surrounding noise conditions and the presence or absence of obstacles.
There is a distance of about 00m, and on average it is around 300m.

As shown in FIG. 5, when the location of the house is at point P, if the user is in an area where the loudspeaker broadcasting of station A and the loudspeaker broadcasting of station B can be heard, the distance between point P and the outdoor slave station is increased. Since the same loudspeaker broadcast arrives with a time difference corresponding to the difference (i.e., the occurrence of an echo), it becomes difficult to hear the contents.

Therefore, in such an area, the master station sends information to the station A and then sends information to the station B after a predetermined time has elapsed, thereby performing time-lag loudspeaker broadcasting and suppressing the occurrence of echo. I do it.

[Problems to be solved by the invention]

As described above, during normal information transmission, time-lag loudspeaker broadcasting is performed to suppress the occurrence of echo, but in an emergency, time-lag loudspeaker broadcasting is not performed, and the same content is broadcasted all at once. .

Therefore, there is a problem that it is difficult for the residents in the area where the echo occurs to hear the contents of the loudspeakers.

SUMMARY OF THE INVENTION It is an object of the present invention to suppress echo generation and make it easier to hear the contents of a loudspeaker broadcast.

[Means for solving the problem]

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

In the figure, reference numeral 2 denotes a measuring means for measuring the volume of a loudspeaker broadcast by a peripheral outdoor station, and reference numeral 3 denotes a volume control signal generating means for generating a volume control signal using the measurement result.

Reference numerals 4 and 5 denote volume control means for controlling the volume of the loudspeaker broadcast by a predetermined amount in accordance with the applied volume control signal.

Then, a control device having a measuring means and a volume control signal generating means at a predetermined point P in an area where an echo occurs when the outdoor individual station simultaneously broadcasts a loudspeaker is provided with a volume control means in a surrounding outdoor child station. When the control device detects the occurrence of an echo, the control device sends a volume control signal to a predetermined outdoor child station of the surrounding outdoor child stations, and lowers the volume of the loudspeaker broadcasting by a predetermined amount. Prevent the generation of echo.

[Action]

According to the present invention, a predetermined point (P
When the control device installed at (point) detects the occurrence of echo, the device sends a volume control signal to a predetermined outdoor slave station to lower the volume of the loudspeaker broadcasting by a predetermined amount so that the service areas do not overlap. To prevent the generation of echo.

For this reason, the control device, for example, sequentially from outdoor slave stations A and B,
The volume of the transmitted simple sound is measured by the measuring means, and the measurement result is stored.

In order to prevent the point P from entering the service area of the outdoor slave station B, for example, using the distance and the measurement result from the point P to the outdoor slave stations A and B, the current outdoor slave station B It is determined in advance how much the volume of the loudspeaker broadcast should be reduced.

When the control device detects the occurrence of an echo, the control device sends a volume control signal to the outdoor slave station B to lower the volume of the loudspeaker broadcast by a predetermined amount, so that the echo is suppressed and the content of the loudspeaker broadcast becomes easier to hear. .

〔Example〕

FIG. 2 is a block diagram of an embodiment of the present invention, and FIG.
The operation | movement explanatory drawing of a figure is shown.

Here, the microphone 21, the volume meter 22 is a component of the measuring means 2, the CPU 31, the transmitter 32 is a component of the volume control signal generating means 3, the receiving parts 41, 51, and the variable resistance parts 42, 52 are the volume controlling means 5 Is shown.

The same reference numerals indicate the same objects throughout the drawings. Hereinafter, the operation of FIG. 2 will be described with reference to FIG. 3, with the two outdoor stations A and B and the point P being one point in the echo generation area (the hatched portion in FIG. 3A).

First, a control device is provided in an echo generation area where the service areas of the outdoor slave stations A and B overlap. And outdoor child station A
Thus, a simple sound of, for example, 1 KHz is loudspeaked at a regular volume from a loudspeaker 13 for loudspeakers via a loudspeaker 12. The control device measures the volume level of each point by the volume system 22 via the microphone 21 and sends the measured volume level to the CPU 31.

Also, by performing the same measurement as above for the outdoor slave station B, a diagram of the service area of the outdoor slave stations A and B as shown in FIG. 3A can be obtained.

Next, as shown in FIG. 3 (b), the service area of the outdoor slave station A and the outdoor slave station B do not overlap, and the control device provided at the point P is the service area of the outdoor slave station A. The amount of decrease in volume of the outdoor slave station B required to enter the area is determined by the CPU.

In this case, the volume of the loudspeaker broadcasting of the outdoor slave station B is obtained from the distance between the outdoor slave station B and the point P, the desired sound volume of the outdoor slave station B at the point P, and the like, and the necessary volume reduction amount can be determined.

Now, in the outdoor slave stations A and B, the emergency broadcast information from the master station extracted by the internal receivers 11 and 15 is broadcast at a regular volume through the loudspeaker amplifiers 12 and 16 and the loudspeaker speakers 13 and 14. do.

The control device inputs measurement data using the microphone 21 and the volume meter 22 to the CPU 31. The CPU determines from this data that an echo has occurred, and sends a volume control signal to the receiving section 41 provided in the outdoor slave station B via the transmitting section 32 and the wireless line.

In the receiving part 41, the level of the drive signal for driving the loudspeaker 14 for loudspeakers is reduced by changing the resistance value of the variable resistor 44 for controlling the output level of the loudspeaker with the extracted volume control signal.

As a result, as shown in FIG. 3 (b), the service area of the outdoor slave station B and the service area of the outdoor slave station A do not overlap with each other, so that the echo generation area is eliminated and the emergency broadcast can be easily heard.

Note that the resistance value of the variable resistor 52 remains 0 since the service area of the outdoor slave station A remains unchanged, but the resistance value is changed when the service area is reduced.

〔The invention's effect〕

As described above in detail, according to the present invention, there is an effect that echo generation is suppressed and the contents of a loudspeaker broadcast can be easily heard.

[Brief description of the drawings]

 FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, FIG. 3 is an operation explanatory diagram of FIG. 2, FIG. FIG. 5 shows an operation explanatory diagram of FIG. In the figure, reference numeral 2 denotes a measuring means, 3 denotes a volume control signal generating means, and 4 and 5 denote volume control means.

Claims (1)

(57) [Claims] 1. A master station, comprising: a plurality of outdoor slave stations with loudspeakers for loudspeakers connected to the master station via a radio line and distributed so as to cover the entire service area; In an information transmission system in which information from a station is broadcasted by the outdoor slave station and transmitted to the residents, a predetermined point P in an area where an echo occurs when the outdoor slave station simultaneously broadcasts a voice is located in a surrounding area. A control device having a measuring means (2) for measuring a volume of a loudspeaker broadcast by an outdoor slave station and a volume control signal generating means (3) for generating a volume control signal using the measurement result is provided. The slave station is provided with volume control means (4, 5) for controlling the volume of the loudspeaker broadcast by a predetermined amount in accordance with the applied volume control signal. Volume is set to a predetermined outdoor slave station among slave stations. It sends a control signal, the echo prevention method being characterized in that the manner reduces the volume of the public address broadcast by a predetermined amount.