JPS58186237A - Speaker sound volume controlling system of radio system - Google Patents

Abstract

PURPOSE:To reset a forced sound circuit at emergent broadcast with a detection signal, by detecting a DC voltage change by rotating a knob of a variable resistor slightly counterclockwise. CONSTITUTION:In normal broadcast, an output 11 of a register 4 turns on an analog switch 9 and an analog switch 6 is turned off, a voice signal is controlled to a suitable volume by a variable resistor 12 and broadcasted from a speaker 10. Further, in the broadcast of forced sound volume, the output 11 of the register 4 turns off of the switch 9 and turns on the switch 6, then the voice signal inputted from an input terminal 1 is broadcasted via the analog switch 6 in the maximum sound volume. In turning counterclockwise the variable resistor by about 10 deg., the reduction in DC voltage is detected at a detection circuit 15, the register 4 is reset with a reset signal 16 from the detection circuit 15, then the analog switch 6 is turned off and the analog switch 9 is turned on, and the sound volume is controlled to a suitable value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the volume of a slave station speaker in a wireless system.

In conventional circular radio telephone systems installed in each municipality, a master station selects a target slave station using a selective call signal and controls the connection of the f-station speaker.

In particular, for emergency broadcasts during disasters, etc., regardless of the adjustment position of the variable resistor (hereinafter referred to as variable resistor) for adjusting the volume of the speaker,
A method is used to report at maximum volume (forced volume).

When a slave station receives a report at a forced volume, the following methods have been used to cancel the forced volume state and receive the call at an appropriate volume, depending on the circumstances of the slave station. There is a method of detecting induced electricity from a commercial power supply through a variable resistor knob and canceling the forced volume just by touching the knob, or a method of canceling the forced volume by using a variable resistor with a switch. It has been suggested that there is a way to turn off the switch. In the former case, the device cannot operate during a power outage, and operation may become unstable depending on the connection between the power cord and the outlet. Moreover, in the latter case, in order to cancel the forced volume and return to the normal volume, it is necessary to turn the variable resistor switch to the OFF position and then return it to the appropriate u value, which is a cumbersome operation.

Also, if the variable resistor is left in the on position, there are problems such as the forced volume not being broadcast.

In order to eliminate these drawbacks, the present invention applies a constant DC voltage to the input terminal r of the variable resistor, detects the change in DC voltage by slightly rotating the knob of the variable resistor to the left, and detects the change in DC voltage. The signal resets the forced volume circuit during emergency broadcasts.

FIG. 1 is a block diagram of a slave station audio circuit showing an embodiment of the present invention, and 1 is an input terminal from a receiver.

2 is a selective ejection circuit, 3 is an output when a forced volume signal is received, and register 4 is set. 5 turns on the analog switch 6 with the output of the register 4, and connects the audio input from the input terminal 1 to the output amplifier 7. Selective discharge circuit 2
The other output 8 is for controlling the connection/disconnection of the speaker 0,
The output amplifier 7 is operated to amplify the outputs of the analog switches 6 and 9, and the speaker 10 is driven. In normal broadcasting, the output 11 of the register 4 turns on the analog switch 9.

Since the analog switch 6 is in the off state, the voice input is controlled to an appropriate volume by the variable resistor 12 and then broadcast. A DC constant voltage source is connected to the terminal 14, and a detection circuit 15 detects a low F of the DC current IL when the variable resistor 12 is turned counterclockwise, and its output 16 resets the register 4. Therefore, when broadcasting at a forced volume, the audio signal is connected through the analog switch 6.

The broadcast will be made at maximum volume, but by turning the variable resistor 12 counterclockwise by about 10 degrees, the reset signal 16 from the detection circuit 15 will turn off the analog switch 6 and turn on the analog switch 9, making it possible to adjust the volume to an appropriate level. It can be adjusted.

13 is a capacitor for direct current, and if the audio signal at input terminal A1 has a stable DC bias, omit the DC constant voltage source at terminal 4.

The output of terminal 1 may be directly connected to variable resistor 12.

Note that this method can be operated correctly in the same state for the next received forced volume signal.

FIG. 2 is a circuit diagram showing details of the detection circuit 15.

18 is an output obtained by lowering the single signal and is constant regardless of the strength of the voice. The output voltage 18 is held at the terminal 19 as it is. 20 is an operational amplifier, and if the human power impedance seen from the input terminal 17 to the operational amplifier side is sufficiently high, it will respond to changes in the DC voltage at the input terminal 17.

The output voltage 18 is the output impedance of the variable resistor and R1
and changes with its own time constant, or the potential of end I19 is ftr
Since it is held in the state of s, the output terminal 721.

The voltage difference is amplified and appears. This output 1'6 is used as a register reset signal.

1) As described above, according to the present invention, the forced volume cancellation function can be realized stably and inexpensively. Turning the volume knob counterclockwise when the volume is too high is a natural behavior, and it is easy to operate.

Note that this method is suitable for f・
It can also be effectively applied to station volume control circuits, etc.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a slave station audio circuit showing an embodiment of the present invention, and FIG. 2 is a detailed circuit diagram of its detection circuit. 2. Selective discharge circuit, 4: Forced volume register. 6.9° analog switch, 7. Increased output mh. 12: Variable resistor for sound adjustment, 15° detection circuit. 20: Operational amplifier.

Claims (1)

[Claims] During normal broadcasting from the master station, the connection of the speaker of the target slave station is controlled by a selective calling signal, and the volume can be adjusted using a variable resistor for adjusting the volume of -f station, and during emergency broadcasting, the selective calling is performed. In a radio system in which a forced volume signal is added to a signal to forcibly maximize the volume of a speaker of station f, the variable resistor for volume adjustment is used as a means for receiving the slave station at an appropriate volume during an emergency broadcast. Connect a DC constant voltage source to the input terminal of the device, and a DC voltage detection circuit to the output terminal. iii. The DC voltage detection circuit detects the DC voltage change that occurs when the knob of the volume adjustment resistor is turned counterclockwise, and this detection signal is used to reset the forced volume circuit for emergency broadcasting. Speaker metering control method for wireless systems.