Telecommunications – Transmitter and receiver at separate stations – Optimum frequency selection
Reexamination Certificate
1996-07-29
2001-09-11
Kincaid, Lester G. (Department: 2682)
Telecommunications
Transmitter and receiver at separate stations
Optimum frequency selection
C455S067150, C455S452200, C455S526000
Reexamination Certificate
active
06289202
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a radio communication apparatus which performs a communication by selecting a radio channel to be used from a plurality of channel groups.
A conventional radio communication apparatus measures the carrier levels of a plurality of radio channels available, determines channels whose carrier levels are equal to or lower than a given reference value as idle channels, and selects an arbitrary one of the idle channels to perform a communication.
When a plurality of such radio communication apparatuses are used within an identical radio area, if a plurality of channels are simultaneously used, as shown in
FIG. 2
, intermodulation waves are generated. For this reason, if an idle channel is merely selected and used, the intermodulation may adversely influence channels in use. In order to eliminate the adverse influence due to the intermodulation, a channel in use which may cause intermodulation with other channels is calculated and stored as an invalid channel, and is excluded from channel candidates to be selected.
However, when a plurality of radio communication apparatuses are used within a single radio area, all the combinations of channels in use may cause intermodulation, and the number of intermodulation waves becomes huge.
Under such conditions, in the above mentioned method that takes intermodulation into consideration upon selection of a channel, intermodulation waves may be generated over a broad range depending on the combination of selected channels, and the number of channels that can be used may become extremely small.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a radio communication apparatus which is capable of performing a maximum possible number of radio communications within a single radio area.
It is another object of the present invention to provide a radio communication apparatus which can easily change the radio channels to be used even when the radio environment during the use of the apparatus considerably changes from that upon setting due to addition of a new radio communication apparatus or addition of equipments such as various OA equipments that may generate radio noise.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.
REFERENCES:
patent: 4419766 (1983-12-01), Goeken et al.
patent: 4481670 (1984-11-01), Freeburg
patent: 4549311 (1985-10-01), McLaughlin
patent: 4751725 (1988-06-01), Bonta et al.
patent: 4811380 (1989-03-01), Spear
patent: 5144466 (1992-09-01), Nakamura et al.
patent: 5295138 (1994-03-01), Greenberg et al.
patent: 5377221 (1994-12-01), Munday et al.
patent: 5666651 (1997-09-01), Wang
patent: 5-48530 (1993-02-01), None
patent: 7-87550 (1995-03-01), None
English Language Abstracts of Japanese Patent Applications Nos. 5-48530 and 7-87550.
Canon Kabushiki Kaisha
Kincaid Lester G.
Morgan & Finnegan L.L.P.
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