JP2887185B2 - Transceiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitting / receiving apparatus that can prevent a signal from being transmitted and received by a transmitter and a receiver at a long distance.

[0002]

2. Description of the Related Art Recently, a transmission / reception device for transmitting / receiving a signal for preventing a lost child in an amusement park, a zoo or the like has been put into practical use. This involves, for example, mounting a receiver on the guardian's side and a transmitter on the child's side.
As a result, a signal including the identification information is transmitted from the transmitter by FM modulation or the like. When the child moves and the transmitter / receiver is separated by more than a predetermined distance ,
Notification means such as a buzzer attached to the receiver operates according to the change in the electric field strength to notify the guardian to prevent further separation.

[0003]

However, in the above-mentioned conventional transmitting / receiving apparatus, a parent or the like having a receiver can look around and take an action such as bringing back the child if the child can be found. If you can't find your child just by looking around, you have to look around. In this case, the notification sound (action) of the buzzer or the like may extend the distance to the child rather than knowing how far the distance is or in what direction.

An object of the present invention is to solve the above-mentioned conventional problems, and to provide a transmitting / receiving apparatus capable of determining a distance and a direction to some extent even when a transmitter and a receiver are separated from each other by a predetermined distance or more. It is an object.

[0005]

Transmission and reception device according to the present invention SUMMARY OF THE INVENTION comprises a transmitter for transmitting a signal including the identification information, and a receiver for receiving a signal transmitted from the transmitter, wherein
The receiver includes means for detecting the electric field strength of the received signal,
The electric field strength of the received signal detected by the output means is a first specified value.
When the reception sensitivity becomes below, the reception sensitivity becomes higher than the first specified value.
Sensitivity switching for switching to the second specified value with high receiving sensitivity
Means and when the receiving sensitivity is set to a first prescribed value
The electric field strength of the received signal became equal to or less than the first specified value.
Sometimes the first notification operation is performed, and the reception sensitivity is changed to the second
After switching to the specified value, respond to the electric field strength of the received signal.
Notification means for performing a second notification operation that changes
It is characterized by having.

[0006]

According to the above means , the receiver receives the signal including the identification information transmitted from the transmitter , and at this time, the receiver receives the signal.
When the electric field strength of the received signal becomes equal to or less than the first prescribed value, the first notifying operation of notifying that a notifying means such as a buzzer emits a notifying sound to notify that the receiving signal exceeds a predetermined distance is performed.
And the sensitivity switching means switches the receiving sensitivity to the second specified value. Thereafter, the notifying means sets the second specified value as a reference.
In accordance with the electric field strength of the received signal , for example, a second notification operation such as shortening the interval at which the buzzer sounds is performed, and the distance and direction can be determined to some extent, so that the search for the transmitter can be easily performed.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.
1A is a circuit block diagram of a transmitter, FIG. 1B is a circuit block diagram of a receiver, FIG. 2 is a circuit block diagram showing a front end, and FIGS. 3 to 5 each show a sensitivity switching method in sensitivity switching means. FIG. 6 is a schematic circuit block diagram illustrating a modification, FIG. 6 is a diagram illustrating reception sensitivity,
FIG. 7 is a diagram for explaining the distance relationship between the transmitter and the receiver at different reception sensitivities. The outer shape (not shown) of the transmitter 1 shown in FIG. 1A is small and easy to carry,
An operation unit 11, a control unit 12 mainly including a CPU, a memory 13, a transmission unit 14, an antenna 15, and a power supply 1
6 and the like.

[0008] In the control unit 12, predetermined identification information stored in the memory 13 (for example, a product number of the transmission / reception device or I / O information such as personal information input from the operation unit 11).
D information) is generated. The transmission signal generated by the control unit 12 is FM-modulated in the transmission unit 14 and transmitted from the antenna 15 at a predetermined frequency.

The receiver 2 shown in FIG. 1B includes an antenna 31 for receiving a signal transmitted from the antenna 15 of the transmitter 1 and a front end 32 for converting the received signal into a signal of an intermediate frequency band. An IF amplifier 33 for amplifying the signal in the intermediate frequency band, a detecting unit 34 for detecting a desired signal from the amplified intermediate frequency band signal, a data shaping unit 35 for shaping the detected signal, A control unit 36 for comparing the shaped data and controlling the entire apparatus; a notification unit 40 for generating a notification signal based on the result of the comparison data output from the control unit 36; , A memory 37 to which the second specified value is input, a power supply 4 for supplying power to the receiver 2, and an IF
From the output of the amplifier 33, the electric field strength of the received signal (receiving sensitivity)
And an A / A 38 for outputting a digital value obtained by digitally converting the measurement output to the control unit 36.
A D converter 39 and a sensitivity switching means 41 for switching the receiving sensitivity to a second specified value by a control signal from the control unit 36 when the digital value is equal to or less than a first specified value.

The control unit 36 is mainly composed of a CPU. The control unit 36 compares the identification information of the signal sent from the data shaping unit 35 with the identification information stored in the memory 37, and checks the electric field strength of the received signal. (Sensitivity) and a specified value, and control of the entire receiver 2 such as elimination of transmission signals from other transmitters and other unnecessary noise signals. As shown in FIG. 2, the front end 32 includes a tuning circuit 42, an FET 45,
It comprises an IF transformer 46, a mixer 47, a local oscillator 48 and the like.

In this embodiment, the sensitivity switching means 41
It is a voltage setting circuit, and the set voltage is switched by a command from the control unit 36, and the voltage to the gate input terminal 44 of the FET 45 is switched to change the amplification factor of the FET 45, thereby changing the reception sensitivity. I can do it. Alternatively, the input terminal 43 to the anode side of the attenuator 49 by the voltage set by the sensitivity switching means 41
, The gate input level of the FET 45 is switched, and as a result, the reception sensitivity is switched. The terminals 43 and 4 are switched by the sensitivity switching means 41.
4 may be switched and set at the same time to switch the receiving sensitivity.

Next, the operation of the transmitting / receiving apparatus according to the embodiment having the above configuration will be described with reference to FIGS. Hereinafter, a case will be described in which the transmitting / receiving device of this embodiment is applied to a device for preventing lost children. In this embodiment, when the receiving sensitivity of the receiver is set to the first specified value (low sensitivity), the distance over which the signal can be received from the transmitter is relatively short, and the receiving sensitivity is set to the second specified value (low sensitivity). When switching to (high sensitivity), the receivable distance of the transmission signal becomes long.

First, the transmitter 1 is carried by a child, and the receiver 2 is carried by a guardian. At this time, the ID numbers of the transmission / reception device and the ID information such as the personal information input from the operation unit 11 are input to the memories 13 and 37. In this case, a low voltage is set in the sensitivity switching means 41, the level of the received signal passing through the attenuator 51 is set low, or
The gate input voltage to T45 is set low, and the reception sensitivity of the receiver is set to the low sensitivity first predetermined value reception capability.

In the transmitter 1, a transmission signal of a predetermined frequency including the FM-modulated identification signal is transmitted from the antenna 15. The transmitted transmission signal is received by the antenna 31 of the receiver 2, converted into a signal of an intermediate frequency band by the front end 32, amplified by the IF amplifier 33, and a desired signal is detected by the detector 34, The signal is shaped by the shaping unit 35, input to the control unit 36, and compared with the identification information and the like input to the memory 37.

On the other hand, the S meter 38 is an IF amplifier 33
Measure the electric field strength (reception sensitivity) of the received signal from the output of
The A / D converter 39 converts the measured output into a digital signal and outputs it to the controller 36. The control unit 36 compares this digital value with the first specified value S1 and calculates a value when the electric field strength is equal to or greater than the specified value S1 (child P1 (transmitter 1) and guardian P2 (receiver 2)). Is the distance L shown in FIG.
When the electric field strength is equal to or less than the specified value S1 (when the distance between the child P1 and the guardian P2 is longer than L0 shown in FIG. 7), the reception of the receiver 2 is continued. The notification means 40 transmits a notification signal such as a buzzer sound at two-second intervals, and the child P1 is moved to the guardian P2 by a distance L0.
Announce that you are farther away.

At the same time, the control section 36 outputs a sensitivity switching signal (control signal) to the sensitivity switching means 41.
The sensitivity switching means 41 to which the switching signal is input changes the supply voltage to one (43 or 44) or both of the two terminals for supplying the gate voltage of the FET 45 of the front end 32, thereby changing the reception sensitivity. Switching to the second prescribed value S2 (see FIG. 6) with high sensitivity. That is, by increasing the supply voltage of the terminal 43, the level of the gate input signal of the reception signal to the FET 45 is increased, or the supply voltage of the terminal 44 is increased.
The amplification factor of the receiver 45 is increased, or the reception sensitivity of the receiver 2 is switched to a higher value by using the amplification factor.

After that, when the notification sound is generated, when the parent P2 determines that the child P1 is not in the field of view, the parent P2 starts searching while moving around the place. Then, the control unit 36
Notifies the guardian P2 of the distance to the child P1 by a notification sound corresponding to the reception sensitivity based on the specified value S2. For example, in the gap "A" between the distances L2 and L0 shown in FIG. 7, a 3-second long buzzer sound having a different interval according to the distance, a buzzer sound with a 2-second interval in the gap "B", and 1 in the distance L1. By changing the buzzer sound at intervals of seconds, the guardian can determine how far the child is away and in which direction they are away from the sound of the notification sound.

Next, a modified example of the sensitivity switching method in the sensitivity switching means will be described with reference to FIGS.
In the modification shown in FIG. 3, an IF amplifier 33a is provided between the front end 32 and the IF amplifier 33, and the amplification degree of the IF amplifier is changed by changing the value of the resistor 33b of the IF amplifier 33a. 2 is changed.

In the modification shown in FIG. 4, a D / A converter 49 is provided between the controller 36 and the S meter 38, and when the electric field intensity is equal to or less than the specified value S1, the controller 36 /
The reception sensitivity of the receiver 2 is changed by changing the output voltage of the S meter 38 via the A conversion unit 49.

Further, in a modification shown in FIG. 5, a switch means 50 (automatic or manual or in combination with both) in which the threshold level for the output signal from the S-meter 38 can be switched in both high and low directions is provided in the control section 36. ) May be provided to change the receiving sensitivity of the receiver 2.

In the same manner as described above in the modified examples shown in FIGS. 3 to 5, after the specified value is switched, the guardian can determine how far the child is separated and in which direction by changing the notification sound. Can be determined. Further, in the above embodiment, the case where the present invention is applied to a device for preventing a lost child has been described. However, the present invention is also applicable to, for example, a device for calling each individual (such as an employee) in a factory. In other words, when handling a large number of receivers whose identification information has been input by a large-capacity transmitter, it is possible to prevent each individual from leaving a callable distance by emitting a notification sound from the receiver, If the user is away from the callable distance, if the sensitivity of the receiver is switched by notification of the notification sound, the reception distance can be extended, and the call of an employee or the like can be performed effectively. Further, the notification means is not limited to a buzzer, but may be variously modified, for example, by vibration, by an optical means such as a lamp, or the like.

[0022]

According to the present invention as described above, according to the present invention, it confirmed by the first notification operation of notifying means when the transmitter and receiver are spaced more than a predetermined distance (e.g., buzzer) (notification sound) After that, it is possible to determine to some extent how far and in what direction they are separated by a different second notification operation (difference in transmission interval) due to a change in the electric field strength of the received signal .

[Brief description of the drawings]

FIG. 1A is a circuit block diagram of a transmitter, and FIG. 1B is a circuit block diagram of a receiver.

FIG. 2 is a circuit block diagram illustrating a front end.

FIG. 3 is a schematic circuit block diagram for explaining a modified example of the sensitivity switching method in the sensitivity switching means.

FIG. 4 is a schematic circuit block diagram for explaining a modified example of the sensitivity switching method in the sensitivity switching means.

FIG. 5 is a schematic circuit block diagram for explaining a modified example of the sensitivity switching method in the sensitivity switching means.

FIG. 6 is a diagram for explaining reception sensitivity.

FIG. 7 is a diagram for explaining a distance relationship between a transmitter and a receiver at different reception sensitivities.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmitter 2 Receiver 11 Operation part 12 Control part 14 Transmission part 15 Antenna 36 Control part 38 S meter 40 Notification means 41 Sensitivity switching means

Claims (1)

(57) [Claims] And 1. A transmitter for transmitting a signal including the identification information, a receiver for receiving a signal transmitted from the transmitter
And a receiver for detecting the electric field strength of the received signal.
And the electric field strength of the received signal detected by the detecting means is
When the reception sensitivity becomes equal to or less than the first prescribed value, the reception sensitivity is set to the first
Switching to a second specified value that has higher receiving sensitivity than the specified value
Means for changing the receiving sensitivity and setting the receiving sensitivity to the first specified value.
The electric field strength of the received signal is equal to the first specified value.
Performs the first notification operation when:
After the sensitivity is switched to the second specified value, the received signal
Notifier performing a second notification operation that changes according to the electric field strength
Receiving apparatus characterized by stages are provided.