JPS637044A - Receiving area checking circuit for radio equipment - Google Patents

Abstract

PURPOSE:To facilitate decision whether an area is a receivable area, and to prevent suspicion, or irritation from occurring, by outputting a carrier signal only for a short time at a prescribed interval by a transmitter, lightening an area display part by a squelch gate circuit at the time of receiving the carrier signal, and also, stopping the operation of a sound output circuit at a time constant circuit. CONSTITUTION:The oscillation circuit 8 of a transmitter 1 always outputs a pulse which repeats such operation to be turned on for one second, and turned off for 25ms. The wave, when a receiver 2 is positioned at the receivable area, is received by the antenna 11 of the receiver, and makes operate a squelch gate circuit 18 only for 25ms through a high frequency signal amplifier 12, and an intermediate frequency amplifier 13. Thereby, a transistor 19 is turned on, and an area display lamp 21 is lightened. Also, since the operation of the circuit for 25ms is not enough to turn on a transistor 25 by a capacitor 23 in a time constant circuit 24, and also, electric charge on the capacitor 23 is discharged at the time of turning off for one second, a sound output circuit 16 is not operated, and the output of clicking, etc., due to noise, can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reception area check circuit for a radio device that can receive signals only within a specific area, and which informs whether or not the area is a place where reception is possible. It is something.

``Conventional technology'' Radio equipment, which uses weak radio waves and can only be received within a specific area, is greatly affected by the conditions of the reception location, and even at very close distances, walls with reinforced steel or high-rise buildings may interfere with reception. In some cases, it may not be available, or it may be possible to receive it even at a long distance. Conventionally, in such cases, transmitters and receivers have been used that do not provide any indication as to whether or not they are capable of receiving signals.

``Problems to be solved by the invention'' However, when radio equipment in cars frequently changes between locations where reception is possible and locations where it is not possible, there may be distrust or irritation due to the inability to receive reception. It was the cause.

"Means for Solving the Problems" The present invention has been made to solve the problems described above, and includes receiving weak radio waves emitted from a transmitter by a receiver in a specific area, and transmitting the signals to a demodulation circuit. In the radio device, the transmitter is equipped with an oscillation circuit that outputs a carrier signal for a short time at predetermined intervals, and the receiver is a squelch gate circuit that operates when the short-time carrier signal is received, an area display unit coupled to the squelch gate circuit, and a time constant for not operating the audio output circuit during the reception time of the carrier signal. It is equipped with a circuit.

"Operation" The transmitter repeatedly transmits a signal that transmits a carrier signal for 25 m seconds and stops the transmitter for 1 second, for example. When the receiver receives this repeated carrier signal, the squelch gate circuit operates for 25 msec to light up the area display section. A time constant circuit is connected to the audio output circuit, and the time constant is 25 msec. Moreover, since this time constant circuit is discharged in the next one second, no sound is output from the speaker. Therefore, if the area display section is blinking, it is determined that the area is in a receivable area, if it is lit continuously, it is determined that communication from the transmitter is in progress, and if it is not lit, it is determined that the area is in a non-receivable area.

"Example" Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows the transmitter (]), and FIG. 2 shows the receiver (2).

The transmitter (1) connects a transmitting antenna (4) to the output side of a transmitter (3), and connects this transmitter (3) to a power terminal (+B).
A transistor (5) is inserted between the
) is connected to the oscillation circuit (8). Further, a transistor (9) is coupled to the contact point between the resistor (6) and the diode (7), and m
A power supply (11) is connected via the word press button (10).

The reception fi (2) includes a reception antenna (11), a high frequency signal amplification circuit (12), an intermediate frequency amplification circuit (13),
It is coupled to a speaker (17) via a demodulation circuit (1, 4), a volume volume (15), and an audio output circuit (16). Further, a squelch gate circuit (18) is coupled to the output side of the intermediate frequency amplifier circuit (13), and this squelch gate circuit (18) is coupled to the base of a transistor (19). The emitter of is coupled to the power supply terminal (10B), the collector is coupled to the area indicator light (21) via the resistor (20), and the resistor (
A time constant circuit (24) consisting of a capacitor (22) and a capacitor (23)
), the other end of the resistor (22) is coupled to the base of a transistor (25), and the other end of the resistor (22) is coupled to the base of a transistor (25).
) has a collector connected to the audio output circuit (16) and an emitter connected to ground.

In the above circuit configuration, the oscillation circuit (8) of the transmitter (1) constantly outputs a pulse that is repeatedly turned on for 1 second and turned off for 25 m seconds, as shown in FIG. 3(a), for example. Therefore, as shown in FIG. 3(b), the transmitter (3) emits radio waves from the antenna (4) that operate for 25 m seconds and stop for 1 second.

When the receiver (2) is in a receivable area, this radio wave is received by its antenna (11), and the high-frequency signal amplification circuit (]
2) The squelch gate circuit (18) operates for 25 m seconds via the intermediate frequency amplification circuit (13). Therefore,
1- transistor (19) turns on, area indicator light (21)
) lights up. That is, it repeatedly flashes on and off for 25 m seconds and off for 1 second to indicate that reception is possible.

In addition, in the ON operation for 25 m seconds, the capacitor (23) of the time constant circuit (24) does not turn on the transistor (25), and the electric charge charged in the capacitor (23) is also discharged during the 1 second OFF operation. Therefore, the audio output circuit (1
6) does not operate, and does not output noise such as clicking sounds.

When the call press button (10) of the transmitter (1) is pressed, the transistor (9) turns on, and regardless of the pulse of the oscillation circuit (8), the transistor (5) turns on continuously, and the transmitter (
3) is activated, and radio waves are continuously emitted from the antenna (4).

When the receiver (2) receives radio waves continuously, the squelch gate circuit (18) operates continuously to turn on the transistor (19), and the area indicator light (21) lights up continuously. Moreover, the capacitor (23) of the time constant circuit (24)
is sufficiently charged, the transistor (25) is turned on, the audio output circuit (16) is activated, and audio is output from the speaker (17). In this case, even if the volume (15) is at the minimum level and no sound is heard from the speaker (17), the area indicator light (21) is lit continuously, indicating that a call is being received.

"Effects of the Invention" Since the present invention is configured as described above, it is immediately possible to determine whether or not the area is available for reception, and it is possible to prevent distrust and irritation caused by not being able to receive reception. This is particularly suitable for cases where the receivable area and non-receivable area change frequently, such as in a vehicle-mounted radio. Furthermore, even if the volume is at the minimum level and no sound can be heard, the continuous lighting indicates the incoming call status, and it can also be used as an incoming call display.

[Brief explanation of drawings]

The figures show an embodiment of a receiving area check circuit for a wireless device according to the present invention.
The figure is a block diagram of the receiver, and FIG. 3 is an output waveform diagram of each part. (1)...Transmitter, (2)...Receiver, (3)...
・Transmission section, (5)...transistor, (6)...resistor, (7)...diode, (8)...oscillator circuit,
(9)...Transistor, (10)...Press button,
(11)...power supply, (12)...high frequency amplifier circuit,
(13)...Intermediate frequency amplification circuit, (14)...Demodulation circuit, (15)...Sound volume, (16)...
Audio output circuit, (17)...Speaker, (J8)...
・Squelch gate circuit, (19)...transistor,
(20)...Resistance, (21)...Area indicator light,
(22)...Resistor, (23)...Capacitor, (2
4)...Time constant circuit, (25)...Transistor. Applicant Fujitsu General Ltd.=8-

Claims (1)

[Claims] (1) In a radio device that receives weak radio waves emitted from a transmitter by a receiver in a specific area, demodulates them by a demodulation circuit, amplifies them by an audio output circuit, and emits sound from a speaker. The receiver includes an oscillation circuit that outputs a carrier signal for a short time at predetermined intervals, and the receiver includes a squelch gate circuit that operates when receiving the short-time carrier signal, and a squelch gate circuit coupled to the squelch gate circuit. 1. A reception area check circuit for a wireless device, comprising an area display section and a time constant circuit for not operating an audio output circuit during reception of the carrier signal.