JPH03204242A - Multifrequency simultaneous radio communication equipment - Google Patents

Abstract

PURPOSE:To exclude beat crosstalk of the third harmonic distortion without limiting the moving range of a slave set by searching a frequency group divided by a called station and setting an idle channel for talking. CONSTITUTION:A channel frequency fc stipulated by the Radio Wave Law is divided into 4 groups 1G-4G of 4 waves each generating no third harmonic distortion and one group 5G of remaining two waves. Similarly, other slave sets search an idle channel in a same group sequentially or simultaneously to set the operating frequency, resulting that the slave sets 5-8 set 4 waves in a same frequency group. Since the frequencies at which the slave sets 5-8 make simultaneous communication in a same area are selected from a frequency group with a relation having no possibility of producing the third harmonic distortion in advance, no third harmonic distortion is generated and no beat crosstalk takes place. Thus, excellent communication is attained independently of talking distance among slave stations and a close distance with a base station antenna.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a small device used for program production in broadcasting studios, halls, etc., stage progression in theaters, etc., or business communication in factories, event halls, etc. The present invention relates to a power multi-frequency simultaneous wireless communication device.

(Prior Art) FIG. 2 is a diagram showing such a conventional multi-frequency simultaneous wireless communication device. 1 is a receiver of base station B, 2 is a transmission controller of the base station, and 3.4 is an antenna.

The receiver 1 is connected to antennas 3 and 4, and the audio system is connected to a transmission controller 2. Further, reference numerals 5 to 8 refer to slave units for base station B, and reference numeral 9 indicates a headset thereof, which is worn by the operator.

10 and 11 are transmitters of the base station B, which are connected to the transmission controller 2. With this configuration, handsets 5 to 8 are able to communicate with base stations or with each other via base stations.

Figure 3 is a diagram explaining the call procedure in the multi-frequency simultaneous wireless communication device as described above. Figure 3 (a) is a flowchart of the procedure, and Figure 3 (b) is the assignment of channel frequencies to be set in the handset. This is a channel table showing an example.

In FIG. 2, for example, when handset 5 calls base station B from the call standby state, handset 5 first presses the talk switch (S (step 1) in FIG. 3(a)) and then calls base station B. An empty channel search is performed to find a channel that is present (S2 in the same example). The empty channel search involves a cyclic search of the 18 frequencies allocated under the Radio Law (currently, however), and when an empty channel is detected (S3), a call is made as determined by this system. The base station B, which is the called station, is called using the channel Cch, and if there is a response (S4, same), the use of the frequency of the detected empty channel is specified (S5, same). As a result, base station B, which is the called station, performs carrier sense reception on the specified channel frequency (S6), and if it is confirmed that the specified frequency is not in use, the base station B performs carrier sense reception on the specified channel frequency. As a result, transmission and reception between the base station B and the handset 5 is started (S7). The other handsets 6 to 8 also set communication channels as described above by sequentially or simultaneously searching for empty channels, and simultaneous mutual communication is started between the four handsets.

In this way, even with conventional multi-frequency simultaneous wireless communication equipment, business calls are possible if you ignore the beat interference that occurs when the distances between the handsets and the base station antenna are approximately the same. .

(Problem to be Solved by the Invention) However, since the conventional multi-frequency simultaneous wireless communication device as described above searches for empty channels by cyclic search, for example, the channel frequencies used by handsets 5, 6, and 7 are may be set to approximately equally spaced frequencies,
At that time, the frequency relationship that causes third-order distortion occurs, and the slave unit 5
and 6 are close to the base station antenna and the antenna input becomes excessive, base station B receives the transmission channel of slave unit 7.
The problem with this receiver was that it caused third-order distortion, resulting in undesirable beat interference.

An object of the present invention is to solve the above-mentioned problems and provide a multi-frequency simultaneous wireless communication device that can eliminate beat interference due to third-order distortion without restricting the movement range of a slave device.

(Means for Solving the Problems) In order to achieve the above object, the present invention does not cause third-order distortion even when simultaneously transmitting and receiving among the frequencies (currently 18 waves) permitted to be used by the Radio Law. The related frequency group (currently 4 waves) is divided into multiple groups (currently 4 groups) and the remaining frequency groups, and the search for an empty channel is performed by searching within these divided groups. This is achieved by using the output frequency as the communication frequency of the handset.

(Function) According to the present invention, the frequency at which four slave units talk simultaneously in the same area is selected in advance from a related frequency group in which there is no risk of third-order distortion occurring, so third-order distortion will not occur. Therefore, since beat interference does not occur, it is possible to carry out a good call, completely unrelated to the communication distance between handsets or the proximity distance to the base station antenna.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1(a) shows an apparatus applied to the present invention, and the configuration is exactly the same as that of FIG. 2.

FIG. 1(b) is a diagram of a channel table explaining frequency groups set in the present invention.

The present invention converts the 18 (currently current) channel frequencies fe stipulated by the Radio Law into 4 channels that do not cause third-order distortion.
It is divided into 4 groups of each wave, IG or 4G, and the remaining 2 groups of 5G.

Similarly, other handsets sequentially or simultaneously search for empty channels in the same group and set the frequency to be used.
For handset 5 to 8, 4 waves in the same frequency group■,■
, ■ and ■ are set.

As described above, the present invention uses four waves within a set frequency group to make a call, and from the beginning, even if third-order distortion occurs, there is a relationship that does not affect each other within the call group. Therefore, even if they are close to each other in the same area or close to the base station, calls can be made without the risk of beat interference, and even when multiple groups or multiple areas are used This has the advantage that interference is less likely to occur.

(Effects of the Invention) As is clear from the above explanation, the present invention eliminates the interference that occurs during simultaneous transmission and reception within a narrow communication area, and further allows the base station receiver to improve reception sensitivity without considering third-order distortion. Since it is possible to increase the number of calls, there is an effect that one call area can be expanded.

[Brief explanation of drawings]

FIG. 1(a) is a diagram illustrating a mode of a multi-frequency simultaneous wireless communication device of the present invention, FIG. 1(b) is a diagram explaining frequency selection in an embodiment of the present invention, and FIG. FIG. 3, which is a diagram of the wireless communication device, is a diagram showing the call procedure thereof. 1... Receiver, 2... Transmission controller, 3, 4...
・Antenna, 5, 6, 7, 8... Handset, 9... Headset, 10.11... Transmitter.

Claims (1)

[Claims] In a low-power multi-frequency simultaneous wireless communication device that has a base station and multiple handsets and is capable of simultaneous multi-frequency calls, the multiple frequencies specified in the Radio Law used for the device are mutually controlled by third-order distortion. The called station sets an empty channel by searching for an empty channel for a call within the frequency group divided into the above groups. A multi-frequency simultaneous wireless communication device characterized by being able to make calls.