JPH0216065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a simplified commercial radio system in which communication is performed between a radio device installed in a mobile station such as a car and a radio device installed in a base station. This invention relates to a transmission activation circuit for a small paging transmitter attached to a mobile station radio. More specifically, if the driver is away from the car and there is a communication from the base station at this time, a ring tone or voice is sent to the small radio receiver that the driver always carries with him as a weak radio signal. This invention relates to a transmission activation circuit for a small paging transmitter that is mounted on and radiates.

``Prior Art'' The transmission activation circuit of a conventional small-sized paging transmitter inputs an audio signal transmitted from a base station to activate the transmitter, and emits this audio input signal toward a small-sized paging receiver. The method is to convert the audio signal transmitted from the base station into a DC trigger signal in advance using a simple commercial radio, start the transmitter with this DC trigger input signal, and then generate the signal generated by the built-in oscillator. There is a method of emitting an oscillating sound (for example, 1kHz) towards a small receiver for calling.
One method was used alternatively.
In other words, the method of starting with an audio input signal is the third method.
As shown in the figure, when there is an audio input signal shown in Figure 3a, that signal is detected as shown in Figure 3b, and the detected signal operates the oscillation/modulation circuit. Then, depending on the audio input signal, Fig. 3c
This modulated radio wave was radiated from the antenna. In addition, the method of starting with a DC trigger input signal is as shown in Figure 4. When the DC trigger input signal shown in Figure 4a is input, the timer circuit is activated by the signal of the 0.2 second delay circuit, and the timer circuit is activated for a certain period of time ( For example, for 60 seconds), the oscillation/modulation circuit is activated, and only during this time, radio waves modulated with intermittent sound at a predetermined frequency (for example, 1KHz) are emitted from the antenna.

"Problems to be Solved by the Invention" Conventionally, a method using an audio input signal and a method using a DC trigger input signal were used alternatively, so a small transmitter for calling using a DC trigger input signal has a DC trigger output. It can only be connected to a simple commercial radio that has a terminal, and conversely, a small transmitter for calling using an audio input signal can only be connected to a simple commercial radio that has an audio signal output terminal, which limits its range of application. The problem was that it was limited.

"Means for Solving the Problems" The present invention has been made to solve the above-mentioned problems, and includes a detection circuit that detects an audio input signal, and a timer circuit that operates for a certain period of time by a DC trigger input signal. , an oscillation/modulation circuit that operates depending on the output of either the detection circuit or the timer circuit, and a modulation signal input to this oscillation/modulation circuit that converts the notification sound signal into an audio signal when the audio input signal is input. It is equipped with a modulation input switching circuit for switching.

"Operation" When a DC trigger signal is input, the timer circuit is activated and the oscillation/modulation circuit oscillates for a certain period of time (for example, 60 seconds). Then, the oscillation signal is modulated by the constantly input notification sound signal (1KHz intermittent sound), and the modulated signal is amplified and radio waves are emitted from the antenna. If there is an audio input signal while the notification sound signal is being output, the oscillation and
The modulation circuit continues to operate, but an audio signal is input with priority over the notification sound signal as a modulation input, and a radio wave of a signal modulated with this audio signal is radiated from the antenna. The timer circuit runs out after 60 seconds, but if the audio signal is longer than the timer output, it will continue to be transmitted until the audio signal runs out.

"Embodiment" An embodiment of the present invention will be described based on FIGS. 1 and 2.

Reference numeral 1 denotes an input terminal for an audio input signal, and a detection circuit 2 and a modulation input switching circuit 3 are coupled to this input terminal 1.

4 is an input terminal for a DC trigger input signal, and this input terminal 4 is connected to a timer circuit 6 which outputs a signal for, for example, 60 seconds via a delay circuit 5 of, for example, 0.2 seconds. This timer circuit 6 and the detection circuit 2 are coupled to an oscillation enable terminal 9 of an oscillation/modulation circuit 8 via an OR circuit 7.

10 is a 4Hz interval timer circuit, for example.
This oscillator 11 is coupled to a 1KHz oscillator 11.
is coupled to the modulation input terminal 12 of the oscillation/modulation circuit 8 via the modulation input switching circuit 3.
The detection circuit 2 is coupled to the oscillation inhibit terminal 13 of the oscillator 11 . Furthermore, an antenna 15 is coupled to the output side of the oscillation/modulation circuit 8 via a multiplication amplifier circuit 14, and the signal is transmitted to a receiver via this antenna 15.

The operation of the above configuration will be explained based on FIG. 2.

Assume that the DC trigger input signal is input to input terminal 4 at _t1 . If this trigger signal is continuously input for 0.2 seconds or more, _the delay circuit 5
A delayed signal is output from , and this delayed signal activates the timer circuit 6, which sends a signal to the oscillation enable terminal 9 through the OR circuit 7, turning on the oscillation/modulation circuit 8 for 60 seconds.

Here, the oscillator 11 is the interval timer 10
Therefore, the signal oscillates (eg, 11 kHz) intermittently at regular intervals (eg, 1 second), and the modulation input switching circuit 3 connects the oscillator 11 to the modulation input terminal 12 of the oscillation/modulation circuit 8. Therefore, the 1KHz intermittent sound is modulated by the oscillation/modulation circuit 8, amplified by the multiplication amplifier circuit 14, and then radio waves are radiated from the antenna 15.

Next, at time t ₃ , the DC trigger input signal is input again, the transmitter is activated by this trigger input signal, and a signal modulated with a 1KHz intermittent tone from the oscillator 11 is transmitted for 60 seconds set by the timer circuit 6. be done.
During this process, if there is a short audio input as shown in FIG. This audio input signal is input to the modulation input terminal 12 of the oscillation/modulation circuit 8, modulated, and its radio waves are radiated from the antenna 15.
When the audio signal disappears at ₅ o'clock, the 1KHz intermittent tone is output again.

From t ₆ o'clock to t ₇ o'clock, there is no DC trigger input signal at all, and only the audio input signal is present.
In this case, only the output modulated by the audio input signal is transmitted. When 60 seconds have elapsed since the timer circuit 6 was started by the DC trigger input signal, transmission is stopped. However, if the audio input signal is
If the transmitter continues to output after the time-up, the transmitter remains active until the audio input signal is cut off.

In the above embodiment, the timer circuit 6 transmits a signal for 60 seconds, but this is because the frequency band used by the small calling transmitter in which the present invention is implemented is extremely congested. This is because the duration of one continuous radio wave emission is limited by legal regulations to 60 seconds or less. Therefore, the present invention is not limited to this, and the length may be longer or shorter as technically necessary.

In the above embodiments, the notification sound signal is an intermittent sound that breaks every second, but this is done in consideration of the length that is easy for humans to hear, and does not have any particular technical meaning. Therefore, the present invention is not limited to this, and the length may be shorter or longer as required.

"Effects of the Invention" Since the present invention is configured as described above, it can be easily configured for any device, whether it is a device that operates only with a DC trigger input signal, a device that operates only with an audio input signal, or a device that is equipped with both. It can be connected, and the range of applications can be expanded sufficiently.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the transmission activation circuit according to the present invention, FIG. 2 is a time chart of the circuit according to the present invention, FIG. 3 is a time chart of only the audio input signal, and FIG. 4 is a DC trigger signal. This is a time chart only. 1... Input terminal for audio input signal, 2... Detection circuit,
3... Modulation input switching circuit, 4... DC trigger input signal input terminal, 5... Delay circuit, 6... Timer circuit, 7
... OR circuit, 8 ... Oscillation/modulation circuit, 9 ... Oscillation enable terminal, 10 ... Interval timer circuit, 11 ... Oscillator, 12 ... Modulation input terminal, 13 ... Oscillation prohibition terminal, 14 ... Multiplication amplifier circuit, 15 ... Antenna.

Claims (1)

[Claims] 1. A detection circuit that detects an audio input signal, and an oscillator that generates an oscillation sound notification signal that is transmitted in place of audio when there is no audio input signal and there is a DC trigger input signal. , a timer circuit that operates for a certain period of time in response to a trigger input signal that instructs the transmission of the notification sound signal; an oscillation/modulation circuit that operates depending on the output of either the detection circuit or the timer circuit; a modulation signal input switching circuit that switches the modulation signal input signal of the circuit so that the notification sound signal is input when the DC trigger input signal is input, and the modulation signal input signal is switched so that the audio input signal is input when the audio input signal is input. A small transmitter for calling, characterized in that the signal of the detection circuit is input to an oscillation prohibition terminal of the oscillator, and input of the notification sound signal to the oscillation/modulation circuit is prohibited when a voice signal is input. Transmission activation circuit. 2. The timer circuit is provided with a delay circuit at the front stage, and the timer is activated only when the DC trigger input signal continues for a certain period of time.
Transmission activation circuit described in section.