Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
1998-10-19
2002-11-26
Chan, Jason (Department: 2633)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S199200
Reexamination Certificate
active
06486992
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a modulating and demodulating method and a transmitting method of a control apparatus and a control apparatus using thereof which is preferably applied to a case in which a wireless communication network or the like is constructed by utilizing infrared ray or the like. In details, when communication is carried out between an apparatus on the controlling side (control node) and an apparatus on the controlled side (controlled node) which function as terminals of wireless communication, modulation sets adopting the same kind of a modulation system having different multiple value formation levels are prepared and an optimum modulation system is selected in accordance with communication distance or communication speed flexibility in respect of participation in a wireless communication network can be provided under more pertinent circuit scale.
Further, when optical transmission is carried out as a wireless communication, in obtaining reception data by receiving an optical signal outputted from a transmitter, the optical signal which is delayed is restricted such that a bit error rate thereof is not deteriorated more than a predetermined bit error rate by which adverse influence of the delayed optical signal is avoided and transmission of data can be carried out at high speed and excellently.
2. Description of the Related Art
In recent years, with progress of spread of portable devices, wireless formation of various analog and digital interfaces is promoted. Particularly, in the field of computer, wireless formation and high speed communication are intensively carried out, for example, by using technologies represented by wireless LAN (local area network) and IrDA (infrared data association), construction of a network (wireless network) by noncontact connection has been progressed not only between portable devices (communication devices or the like) disposed in the same room but also between a portable device and an installed device (television receiver or the like).
According to the wireless network, there is constructed a network in which one device constitutes a parent node (control node) and remaining one or more of devices constitute child nodes (controlled nodes) and communication between the parent node and the child nodes is connected by optical communication utilizing infrared ray or the like.
FIG. 1
shows a case in which a wireless communication network is constructed by one parent node
10
and one or more, three in this example of child nodes
20
(
20
A,
20
B and
20
C). Means (transmitting means and receiving means) for carrying out optical communication by infrared ray are installed at insides of the respective nodes
10
and
20
. The child node
20
can communicate with only the parent node
10
by carrying out communication in synchronism with each other by using infrared ray.
When such a network for wireless communication is constructed, as a modulation system used in communication between the respective child nodes
20
and the parent node
10
, the following cases are conceivable.
(1) The same modulation system is adopted for the parent node
10
and the child nodes
20
.
(2) The respective nodes adopt different modulation systems.
Meanwhile, the following problems are conceivable in the above-described wireless communication means. That is, when the system (1) mentioned above is adopted as a communication system in carrying out data communication in order to simplify communication control and reduce the circuit scale as less as possible, the communication control is simplified since the same modulation system is adopted in the respective communication, however, transmission speed and communication distance between the nodes are fixed by the adopted modulation system and accordingly, a communication system which is devoid of flexibility is constituted.
Therefore, in order to carry out higher speed communication, the problem cannot be dealt with unless the modulation system is changed and when lower speed communication is sufficient, a wasteful equipment is provided. Because the circuit scale cannot be reduced.
Further, according to the system (2), when different modulation systems are adopted in communication between respective nodes such as between the parent node
10
and the child node
20
A or the parent node
10
and the child node
20
B, in the respective child nodes
20
A,
20
B and
20
C, synchronizing circuits in correspondence with the modulation systems used by the respective child nodes become necessary and further, the communication control is also complicated.
Further, when transmission of data is carried out by using an optical signal of infrared ray or the like, on the reception side, as shown by
FIG. 2
, a direct signal from the transmission side and an optical signal which is delayed by being reflected by a reflecting object are supplied. Therefore, multiple paths are caused by a direct signal shown by
FIG. 3A and a
reflected signal (ghost signal) shown by
FIG. 3B
in which the signal level of the direct signal is attenuated and the signal is delayed and a reception signal shown by
FIG. 3C
is outputted from the reception side.
In this way, the signal waveform of the reception signal is changed by reflection of the signal and accordingly, S/N ratio (signal to noise ratio) is deteriorated, when the data transmission speed becomes fast, influence of the change in the signal waveform is significant and data cannot be transmitted correctly.
Therefore, in order to remove such an adverse influence by the multiple paths, for example, there is carried out a processing in which in starting data transmission, predetermined data is transmitted and received, influence of multiple paths is confirmed and adverse influence of multiple paths is removed from a reception signal in data transmission thereafter. However, according to a method of using so-to-speak adaptive automatic equalization where data transmission is carried out correctly by removing influence of multiple paths, circuits for removing influence of multiple paths are added and load of signal processing for removing influence of multiple paths is increased.
SUMMARY OF THE INVENTION
Hence, it is an object of the present invention to be able to construct a wireless communication network without excessively enlarging circuit scale and which is rich in flexibility by being able to select a pertinent modulation system in accordance with communication distance and communication speed.
Further, it is an object of the present invention to provide an optical transmission method and an optical transmission apparatus capable of transmitting data at high speed and excellently by precisely and simply restricting multiple paths.
In order to resolve the above-described problems, according to one aspect of the present invention, there is provided a modulating and demodulating method of a control apparatus, wherein in a wireless communication network in which one or more of controlled control apparatuses are present in respect of one control apparatus and mutual communication is carried out between the control apparatus and the controlled control apparatuses by using infrared ray or the like, modulation sets comprising a same kind of a modulation system having different multiple value formation levels are prepared for the controlled control apparatuses, a modulation system is selected from the modulation sets in accordance with communication distance and communication speed necessary for the controlled control apparatuses and a signal is modulated by using the selected modulation system.
According to another aspect of the present invention, there is provided a control apparatus, wherein in a wireless communication network in which one or more of controlled control apparatuses are present in respect of one control apparatus and mutual communication is carried out between the control apparatus and the controlled control apparatuses by using infrared ray or the like, the controlled control apparatuses are respectively inst
Mihota Norihito
Sasaki Takatsuna
Chan Jason
Frommer & Lawrence & Haug LLP
Leung Christina Y
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