JPH0129103B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a speaker volume control method in a wireless receiving slave station.

FIG. 1 shows a block diagram of a conventional slave station audio circuit. Conventionally, in broadcast radio telephone systems installed in each municipality, a target slave station is selected by a selective call signal from a master station, and the speaker connection of only the called slave station is controlled. For such emergency broadcasts, a forced volume control signal is used to forcibly amplify the sound from the speakers at the maximum volume (hereinafter referred to as forced volume control), regardless of the setting position of the volume control variable resistor of the slave station. . If a slave station is currently controlled by forced volume, we will explain how to release it. The signal input from input terminal 1 indicates that the local station has been called by selective call receiving circuit 2;
It identifies that the volume is controlled by forced volume, and outputs the output to the amplifier 5 and register 3. When the output of the register 3 is input to the connection circuit 4, the signal input from the input terminal 1 is directly connected to the amplifier 5 and amplified by the speaker 6. Even if the user tries to lower the volume by operating the volume adjustment variable resistor 7 in order to control the volume of the speaker 6, the connection circuit 4 will forcefully control the volume. In order to release this, operate the switch 8 attached to the volume adjustment variable resistor 7 (actually, set the volume of the volume adjustment variable resistor to the minimum, and then turn it further to turn the switch 8). The register 3 is reset, the connection circuit 4 is disconnected, and the volume adjustment variable resistor 7 is set to an appropriate position to adjust the speaker volume.

The above-mentioned operation is troublesome and has the disadvantage that unless the switch 8 is restored, it will not operate correctly in response to the next received forced volume control signal.

In order to eliminate these drawbacks, the present invention adds a voltage detection variable resistor that is linked to the volume adjustment variable resistor, and the voltage detection variable that is generated by rotating the knob of the volume adjustment variable resistor. This detects the change in DC voltage across the resistor, and uses this detection signal to reset the forced volume circuit.

FIG. 2 shows a block diagram of a slave station audio circuit according to an embodiment of the present invention. Circuits having the same meaning as those in FIG. 1 are indicated by the same symbols. A method of canceling the state in which the receiving slave station is selectively called and controlled by forced volume will be described below. Reference numeral 10 denotes a voltage detection variable resistor that is interlocked with the volume adjustment variable resistor 7, and when the user operates the volume adjustment variable resistor 7, the voltage detection variable resistor 10 is also activated at the same time. Since the voltage detection variable resistor 10 is connected between the DC power supply Vc and the ground, a change in resistance value is input to the detection circuit 9 as a change in DC voltage. The detection circuit 9 resets the register 3 when detecting a change in the DC voltage.
This disconnects the connection circuit 4, so
The volume adjusting variable resistor 7 can be set to any volume position. Further, once the forced volume is canceled, the next received forced volume control can be operated correctly regardless of the setting position of the variable resistor 10.

As explained above, according to the present invention, in order to control the volume of a slave station speaker subjected to forced volume control,
This can be done with simple operations, and erroneous operations can be avoided.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a slave station audio circuit showing a conventional example, and FIG. 2 is a block diagram showing an embodiment of the present invention. 1: Input terminal, 2: Selective call receiving circuit, 3: Register, 4: Connection circuit, 5: Amplifier, 6: Speaker, 7: Variable resistor for volume adjustment, 8: Attached switch, 9: Detection circuit, 10: Variable resistor for voltage detection.

Claims (1)

[Claims] 1. In a wireless system that transmits a selective call signal and a forced volume signal from a master station during an emergency broadcast, sets the forced volume circuit of the target slave station, and forcibly controls the volume of the speaker of the slave station to the maximum. A voltage detection variable resistor to which a constant DC voltage is applied is added to the volume adjustment variable resistor of the slave station, and is connected to this variable resistor, and by rotating the knob of the volume adjustment variable resistor. A speaker volume control method for a wireless system, characterized in that a detection circuit detects a DC voltage change that occurs in the voltage detection variable resistor, and the forced volume circuit is reset using this detection signal.