Communications: electrical – Continuously variable indicating – With meter reading
Reexamination Certificate
1997-08-22
2001-01-30
Horabik, Michael (Department: 2735)
Communications: electrical
Continuously variable indicating
With meter reading
C307S010200
Reexamination Certificate
active
06181252
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is related to and incorporates herein by reference Japanese Patent Application No. 8-222044 filed on Aug. 23, 1996.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a remote control system and method which is used for a vehicular wireless door control system or the like.
2. Description of Related Art
In a remote control system employed conventionally in a vehicular wireless door control system, from the standpoint of restricting unauthorized uses of a vehicle, a transmission code to be transmitted from a transmitter is ciphered so as not to be deciphered. In the system disclosed in JP-A 8-102982 U.S. Pat. No. 08/510,469 filed on Aug. 2, 1995), for instance, a transmission code is ciphered by the use of a rolling code which is updated in the predetermined order each time the rolling code is transmitted from a transmitter to a receiver.
According to this system, as the rolling code is updated each time in the predetermined order, a design engineer who has designed the system (transmitter and receiver), and hence the updating order of the rolling code, can decipher the transmission code thus ciphered. This may possibly result in the unauthorized uses of the system by the design engineer, for instance.
SUMMARY OF THE INVENTION
The present invention has an object to provide a remote control system and method which disables even a system design engineer to decipher a transmission code transmitted from a transmitter to a receiver.
The present invention has an object to provide a remote control system and method in which a transmission code to be transmitted from a transmitter to a receiver includes a rolling code ciphered by the use of a system-specific code.
For attaining the above object, according to the present invention, a transmitter ciphers a rolling code based on a system-specific code specifically set for each system to generate a ciphered rolling code, and ciphers an ID code by the use of the ciphered rolling code. Thus, as long as the key code set specifically for the control system is kept undisclosed, it becomes difficult even for such an engineer, who is engaged in determining a rolling code generating algorithm, to decipher the ciphered rolling code. As a result, deciphering is made to be more difficult so that an unauthorized use by other than the owner of the control system may be restricted.
Preferably, the rolling code is generated by repeating a logic operation and an Maximum shift keying a plurality of times, so that the deciphering of the rolling code is made much more difficult.
Preferably, the system-specific code is set and stored in a nonvolatile memory in a production process of the system, not at the time of system designing process, so that the ciphered rolling code may not be deciphered as long as the system-specific code is kept undisclosed or the system-specific code is determined randomly at the production process.
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patent: 4596985 (1986-06-01), Bongard et al.
patent: 5552789 (1996-09-01), Schuermann
patent: 5600324 (1997-02-01), Reed
patent: 5708307 (1998-01-01), Iijima et al.
patent: 5733047 (1998-03-01), Furuta et al.
patent: 5774065 (1995-08-01), Mabuchi et al.
patent: 8-144595 (1996-06-01), None
patent: 8-182058 (1996-07-01), None
patent: 8-170457 (1996-07-01), None
patent: 8-182078 (1996-07-01), None
patent: 8-260783 (1996-10-01), None
Denso Corporation
Horabik Michael
Pillsbury Madison & Sutro LLP
Shimizu M
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