The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 14, 1995
Filed:
Jun. 13, 1994
Michihiro Izumi, Kawasaki, JP;
Kazunari Watanabe, Yokohama, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A telephone exchange system of this invention has a terminal connected to an extension by radio. As a radio communication modulation method, a spread spectrum method is used. A speech signal received from a line by the telephone exchange system is exchanged by an exchange switch, and is supplied to a data conversion unit. The data conversion unit causes a serial/parallel converter to covert a serial input signal into a parallel signal. The converted parallel signal is subjected to spread-spectrum modulation in units of parallel bits. The modulated signal bits are added to each other by an adder, and the sum signal is multiplexed on a carrier signal. The multiplexed signal is transmitted to the terminal. Upon reception of the signal, the terminal causes a phase synchronization circuit to generate an inverse spread code corresponding to a spread code, and synchronized with the reception signal, and inversely spreads the reception signal using the generated inverse spread code. The inversely spread signal is converted into a serial signal by a parallel/serial converter, i.e., is demodulated into a speech signal. When a signal is transmitted from the terminal, the said procedure as described above is executed in the opposite direction.