JP2840792B2 - Wireless transmitter having interference prevention function and wireless transmission control system using the same - Google Patents

Description

The present invention relates to a wireless transmitter having an interference prevention function and a wireless transmission control system using the same.

[Related Art] Recently, various wireless transmission control systems have been developed in which a wireless signal such as a weak radio wave is transmitted from a wireless transmitter, and the wireless receiver receives the wireless signal and performs necessary control. Have been.

As an example of such a system, a wireless service call used in a restaurant or the like will be described as an example. As shown in FIG. 5, each table is provided with a wireless transmitter 100. Wireless receiver 200 having a plurality of display windows 200a at the place
When the customer operates the operation switch (not shown) of the wireless transmitter when necessary,
A radio signal with an ID code is transmitted, the radio signal is received by the wireless receiver 200, and the table number of the called page is displayed on the display unit 200a, so that quick service can be performed. It is a system that can do it.

However, in such a system, since the radio signals output from each wireless transmitter 100 are configured using the same frequency carrier, the transmission of the radio signals transmitted from the plurality of wireless transmitters 100. If the timings overlap, the receiver 200 cannot perform normal reception processing due to interference between radio signals.

In order to avoid such inconveniences, FIG.
As shown in (c), each wireless transmitter (A, B,
C) If the operation switch of 100 is operated once, the radio signal of the same transmission data is repeatedly transmitted plural times in each of the predetermined periods T1, T2, T3,. Some transmitters are designed to prevent interference on the receiver 200 side.However, in such a system, improvements in the number of transmitters 100 become more complicated as the number of transmitters 100 increases, making the setting of the repetitive transmission cycle and the number of transmissions more complicated. Was rare.

[Problem to be Solved by the Invention] The present invention proposed in view of the above situation is such that when a wireless signal is being transmitted from another transmitter, the transmission of the wireless signal is stopped before the transmission is started. It is an object of the present invention to provide a wireless transmitter capable of completely preventing interference on the receiver side.

It is another object of the present invention to provide a wireless transmission control system using the wireless transmitter.

[Means for Solving the Problems] According to the invention of claim 1 proposed to achieve the above object, when a transmission switch is operated, a transmission band is monitored and received prior to transmission of a wireless signal. A monitor receiving unit that determines the presence or absence of a wireless signal transmitted from another transmitter, and when a wireless signal from another is not received by the monitor receiving unit, the wireless signal is transmitted immediately while a wireless signal from the other is transmitted. When the wireless signal is received, a signal processing unit that waits for the transmission of the wireless signal until the wireless signal is stopped is provided.

According to a second aspect of the present invention, there are provided a plurality of wireless transmitters according to the first aspect and a wireless receiver that receives wireless signals transmitted from these transmitters and performs necessary control. It is configured.

[Operation] According to the first aspect of the present invention, when the transmission switch is operated, the control signal is transmitted from the signal processing unit to the monitor reception unit, and the monitor reception of the wireless signal is performed. When it is determined that a wireless signal is not being transmitted from another device, a transmission permission signal is returned to the signal processing unit. Transmits and sends out wireless signals. However, when the monitor reception unit determines that a wireless signal is being transmitted from another wireless transmitter, the monitor unit returns a transmission standby signal to the signal processing unit, and the signal processing unit returns the transmission standby signal returned from the monitor reception unit. After waiting until the transmission stops, the wireless signal is transmitted in the same manner by returning the transmission permission signal.

According to the second aspect of the present invention, while a wireless signal is being transmitted from one wireless transmitter, transmission is in a standby state even when another wireless transmitter is operated, so that no interference occurs on the wireless receiver side. Receive wireless signals reliably.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.
In the following description, a configuration using a radio signal as a wireless signal will be described.

FIG. 1 shows an example of the internal configuration of a wireless transmitter 1 according to the present invention. In the figure, reference numeral 10 denotes a signal processing unit having a transmission switch 10a, and 11 monitors a radio signal received by a receiving antenna RA. The monitor receiving unit 12 is a wireless transmitting unit that transmits a radio signal from the transmitting antenna TA.

The signal processing unit 10 transmits a control signal to the monitor reception unit 11 by operating the transmission switch 10a to start monitor reception, and in accordance with the determination signal returned from the monitor reception unit 11,
An operation of immediately starting transmission of a wireless signal or waiting for transmission of a wireless signal is performed.

The monitor receiving unit 11 receives the control signal transmitted from the signal processing unit 10, receives the radio signal in the same frequency band as the radio signal transmitted from the wireless transmitting unit 12, monitors and receives the radio signal via the receiving antenna RA, and receives other signals. When it is determined that the radio signal is being transmitted from the transmitter, a transmission standby signal is returned to the signal processing unit 10, but when it is determined that the radio signal is not transmitted from another transmitter, the transmission permission signal is transmitted. Is performed.

Further, wireless transmission section 12 receives transmission data transmitted from signal processing section 10, generates a wireless signal in which a carrier is modulated, and transmits the signal from transmission antenna TA.

The operation of the wireless transmitter 1 having such a configuration is described in the second section.
This will be described with reference to the time chart in FIG.

1. Operation when no radio signal is transmitted from another transmitter.

When the transmission switch 10a is operated, a control signal is transmitted from the signal processing unit 10 to the monitor reception unit 11.

When the monitor receiving unit 11 receives a radio signal via the receiving antenna RA and determines that a radio signal in the same frequency band as the radio signal to be transmitted is not being transmitted, the signal receiving unit 11 transmits a transmission permission signal to the signal processing unit 10. Reply.

Upon receiving the transmission permission signal, the signal processing unit 10 immediately transmits the transmission data to the wireless transmission unit 12 and sends out the radio signal via the transmission antenna TA.

2. Operation when a radio signal is being transmitted from another transmitter.

When the transmission switch 10a is operated, a control signal is transmitted from the signal processing unit 10 to the monitor reception unit 11.

The monitor receiving unit 11 receives a radio signal via the receiving antenna RA, and determines that the radio signal in the same frequency band as the radio signal to be transmitted is being transmitted to the signal processing unit 10. The transmission standby signal is continuously returned, and a transmission permission signal is returned when it is determined that the transmission of the radio signal has stopped.

The signal processing unit 10 waits for a transmission operation while the transmission standby signal is returned from the monitor reception unit 11, and transmits the transmission data to the wireless transmission unit 12 when the transmission permission signal is input, and transmits the radio wave. The signal is transmitted from the transmitting antenna TA.

As described above, the wireless transmitter 1 of the present invention always checks whether a radio signal is transmitted from another transmitter prior to transmission of a radio signal. It is possible to completely prevent interference on the side. In particular, in the case of a wireless transmitter that requires some time to transmit a series of radio signals, the probability of competing with radio signals transmitted from other wireless transmitters is extremely high. The use of a device makes it possible to completely prevent such competition of radio signals.

FIG. 3 shows an example of a wireless transmission control system configured using the above-described wireless transmitter 1, and is based on the operation time charts of the wireless transmitters shown in FIGS. 4 (a) to (f). As can be seen, when a wireless signal is being transmitted from any of the transmitters 1, even if the transmission switch is operated by another transmitter 1, the transmission is on standby, so that the time chart of FIG. As shown, the receiver 2 completely prevents interference.

In the above description, the case where a radio signal is used as a wireless signal has been described as an example. However, interference can be similarly prevented when an optical signal or an ultrasonic signal is used in addition to the radio signal. It is possible.

According to the present invention, prior to transmission of a wireless signal,
Since the transmission band is monitored and the transmission is suspended when the wireless signal is being transmitted, it is possible to provide a wireless transmitter capable of preventing wireless signals from competing and effectively preventing interference.

[Brief description of the drawings]

FIG. 1 is a block diagram of a wireless transmitter according to the present invention;
FIG. 2 is a time chart for explaining the operation, FIG. 3 is a structural example of a wireless transmission control system using the wireless transmitter, and FIG. 4 is a wireless signal transmitted from the wireless transmitter and the receiver side. FIG. 5 is a time chart for explaining a wireless signal received by the conventional wireless service call system, and FIG.
The figure is a time chart for explaining the operation of the wireless transmitter used in the system. [Description of Signs] 1 ... Wireless transmitter 10 ... Signal processing unit 10a ... Transmission switch 11 ... Monitor receiving unit 2 ... Wireless receiver

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H04B 1/00 H04B 7/00 G08B 5/00

Claims (2)

(57) [Claims] 1. A wireless transmitter for transmitting a wireless signal containing necessary transmission data in response to an operation of a transmission switch, wherein when the transmission switch is operated, a transmission band is set prior to transmission of the wireless signal. A monitor receiving unit that receives a monitor and determines the presence or absence of a wireless signal transmitted from another transmitter; and when the monitor receiving unit does not receive a wireless signal from another, immediately transmits the wireless signal, and When the wireless signal of
And a signal processing unit that waits for transmission of the wireless signal until the wireless signal stops. A wireless transmitter having an interference prevention function. 2. A wireless communication system comprising: a plurality of wireless transmitters according to claim 1; and a wireless receiver that receives wireless signals transmitted from these transmitters and performs necessary control. Wireless transmission control system.