JP2000137886A - Transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of saturation in the reception sensitivity values of all receivers receiving radio waves from a transmitter. SOLUTION: When a depression switch 10 is depressed, CPU 11 closes a switch 17 and transfers prescribed data to a modulation part 12. The data is radio-transmitted and the plural series circuits of resistors and switches are connected to the amplifier 15 of a final stage in parallel. The resistors R1 and R2 are those for deciding transmission outputs and the transmission outputs can be switched manually by the change-over of the switches S1 and S2. Thus, the key 10 of a transmitter is depressed in various parts while the transmission output is switched after the installation of the receivers. When the received sensitivity values of the respectively receivers at that time are checked, the transmission output without the saturation of the reception sensitivity values of all the receivers receiving radio waves from the transmitter can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitter for use in a position detecting system.

[0002]

2. Description of the Related Art A position detecting system is used for various purposes. Here, a case of a position detecting system constructed for security purpose will be described.

[0003] When guarding a building, a guard may periodically patrol the building while the building is unmanned. If any abnormality is found during the patrol, it is necessary to inform the monitoring center of the area in which the abnormality is found. In such a case, a position detection system is used to know in which area the guard is currently located.

Now, consider a case as shown in FIG. FIG. 2 is a diagram showing a plane of a certain floor of a building. It is assumed that the floor has rooms A, B, C, and D and five sections of a passage E. The receiver 1 is installed in each of the rooms A to D and each area of the passage E. The receiver 1 can be mounted on the ceiling or mounted on the floor, but may be any type.

[0005] The patrol guard carries a transmitter. This transmitter is usually small enough to fit in the palm of your hand. FIG. 3 shows a configuration example of the transmitter. In FIG. 3, 1
0 is a push button switch (hereinafter simply referred to as a button),
11 is a CPU, 12 is a modulation unit, 13 is an amplifier, 14 is a filter, 15 is an amplifier, 16 is a battery as a power supply, 17
Indicates a switch, and 18 indicates an antenna.

[0006] The button 10 is always open. One of the buttons 10 is grounded, and the other is connected to an interrupt terminal of the CPU 11. The switch 17 is always open, and is closed by the CPU 11 only when transmitting data. Therefore, power is always supplied from the battery 16 to the CPU 11, but power is supplied to the modulation unit 12, the amplifier 13, the filter 14, and the amplifier 15 only when data transmission is performed.

[0007] When the guard finds an abnormality during the patrol, he pushes the button 10. When button 10 is pressed, CPU
11 is interrupted. Then, when an interrupt occurs, the CPU 11 closes the switch 17 and passes data to be transmitted to the modulator 12. Then, this data is modulated by the modulator 12, amplified by the amplifier 13, band-limited by the filter 14, further amplified by the amplifier 15, and transmitted by radio from the antenna 18. The data to be transmitted may be any data, but usually, an ID number or the like assigned to a guard who carries the transmitter is used. In this manner, it is possible to know which guard has pressed the button 10 of the transmitter in which area, as will be apparent from the description below.

[0008] Thus, the data transmitted from the transmitter is received by the receiver 1. FIG. 4 shows a schematic configuration example of the receiver 1. 4, reference numeral 20 denotes an antenna, 21 denotes a receiving unit, 22 denotes a CPU, and 23 denotes a transmitting unit.

Upon receiving the signal, the receiving section 21 demodulates the transmitted data, detects the reception sensitivity value at the time of reception, and passes the data and the reception sensitivity value to the CPU 22. This reception sensitivity value is called RSSI.

The CPU 22 passes the data and the receiving sensitivity value to the transmitting section 23, and causes the data and the receiving sensitivity value to be transmitted to a center device (not shown in FIG. 2). The center device is installed at a security center or the like of the building. The transmission of the data and the reception sensitivity value to the center device may be performed by wire or wirelessly.

As described above, if a security guard finds an abnormality in a certain area and presses the button 10 of the transmitter, not only the receiver in that area but also the receivers in other areas will be affected by the transmitter. The receiver may receive radio waves from these receivers, and those receivers transmit the received data and reception sensitivity value to the center device.

The center device compares the reception sensitivity values from the respective receivers, determines which receiver has the highest reception sensitivity value, and installs the receiver having the highest reception sensitivity value. In addition to displaying the area that has been set, the received data is displayed. This is because it is determined that the receiving sensitivity value of the receiver installed at the position closest to the position where the button 10 of the transmitter is pressed is the highest.

Therefore, the person in charge of the center device can know which area has an abnormality by observing the displayed area. Also, as mentioned above,
If the ID number of the guard is used as the data transmitted from the transmitter, the ID number is displayed on the center device as the received data. Is pressed, that is, which guard has found the abnormality.

In FIG. 3, only one button 10 is used. However, it is conceivable that one button may be erroneously pressed. Therefore, in recent years, two buttons are provided on the transmitter, and these two buttons are used. C only if buttons are pressed simultaneously
There are some that make the PU11 interrupt.
In the present invention, whether the number of buttons is one or two is not an essential matter in the present invention.
It is said that it is an individual. This is the same in the following.

[0015]

By the way, the transmission output of the conventional transmitter is made as large as possible. Under the current law, the transmission power allowed for this type of transmitter is a maximum of 10 mW, so that the transmission power of the conventional transmitter is 1 mW.
Usually, it is set to 0 mW. The reason why the transmission output is set to the allowable limit is that the radio wave transmitted from the transmitter must not reach the receiver 1. Conventionally, the transmission output of the transmitter is fixed.

As described above, since the transmission output of the transmitter is conventionally set to the allowable limit, the radio wave from the transmitter depends on the location of the receiver installed in each area or the area of each area. The receiver sensitivity values of all the receivers that have received the signal cause saturation, and there is no difference in the receiver sensitivity values of the respective receivers, and the center device can specify in which area the button 10 of the transmitter has been pressed. There is a possibility that a situation of disappearing may occur. Such a situation becomes conspicuous when the area of the area is small.

The present invention has been made in order to avoid the above-described situation, and it is possible to prevent the reception sensitivity values of all the receivers receiving radio waves from causing saturation. It is intended to provide a transmitter.

[0018]

In order to achieve the above-mentioned object, a transmitter according to the present invention is a transmitter used in a position detecting system, wherein a transmission output is manually switchable. And

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a transmitter according to the present invention. In the figure, S1 and S2 indicate switches, and R1 and R2 indicate resistors. In FIG. 1, the same components as those shown in FIG. 3 are denoted by the same reference numerals, and duplicate description will be omitted.

A plurality of series circuits of resistors and switches are connected in parallel to the amplifier 15 which is the final stage amplifier. In the figure, a series circuit of a resistor R1 and a switch S1 and a series circuit of a resistor R2 and a switch S2 are connected in parallel. Of course, three or more series circuits of the resistor and the switch may be connected in parallel. This resistance R
Reference numerals 1 and R2 denote resistors for determining the transmission output, for example, the load resistance of the amplifier 15. Also, the switches S1,
At least one of S2 is closed. In the figure, switch S2 is closed and switch S1 is open. These switches S1 and S2 are manually switched.

That is, in this transmitter, the switches S1,
By switching S2, the transmission output can be manually switched. For example, in the case of FIG. 1, the transmission output depends on the resistance value of the resistor R2. If the switch S1 is closed and the switch S2 is open, the transmission output is determined according to the resistance value of the resistor R1, and if both the switches S1 and S2 are closed, the transmission output is determined. It is determined by the combined resistance value of R2.

Next, a method of determining the transmission output of the transmitter shown in FIG. 1 will be described. First, each floor is divided into zones, and a receiver is installed in each zone. Then, after the receivers are installed, buttons 10 of the transmitter are pressed at various places, and the reception sensitivity values of the respective receivers at that time are checked. By performing such a test by switching the transmission output of the transmitter, a transmission output that does not cause the saturation of the reception sensitivity values of all the receivers that have received the radio wave is obtained, and the switch S1 is set so that the transmission output is obtained. , S2
Should be set.

The switches S1 and S2 are preferably provided inside the cover of the transmitter. These switches S1, S
This is because if the cover 2 is outside the cover, it is possible that the switch will be erroneously switched.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and it is apparent to those skilled in the art that various modifications are possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a transmitter according to the present invention.

FIG. 2 is a diagram for explaining a position detection system constructed for security purposes.

FIG. 3 is a diagram illustrating a configuration example of a conventional transmitter used in a position detection system.

FIG. 4 is a diagram illustrating a configuration example of a receiver used in the position detection system.

[Explanation of symbols]

1 ... Receiver, 10 ... Push button switch, 11 ... CP
U, 12: modulator, 13: amplifier, 14: filter, 1
5 ... amplifier, 16 ... battery as power supply, 17 ... switch, 18 ... antenna, 20 ... antenna, 21 ... receiver,
22 ... CPU, 23 ... Transmission unit.

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Claims (1)

[Claims] 1. A transmitter for use in a position detection system, wherein a transmission output is manually switchable.