Multiplex communications – Duplex – Communication over free space
Reexamination Certificate
1997-07-30
2001-05-15
Jung, Min (Department: 2731)
Multiplex communications
Duplex
Communication over free space
Reexamination Certificate
active
06233227
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transmitting and receiving apparatus which uses a frequency division multiple access (FDMA) system for a multiple access system and a time division duplex (TDD) system for a bidirectional communication system. Particularly, it relates to a high frequency circuit block of a mobile station (hand set) or a base station (base unit) in that system.
2. Description of the Related Art
A transmitting and receiving apparatus such as a digital cordless telephone or the like employing a CT-2 system which is widely adopted in Europe, etc. uses the FDMA system for the multiple access system and uses the TDD system for the duplex system.
A system for connecting to a specified destination of communication in a communication space which is simultaneously utilized by a plurality of users is called multiple access. The CT-2 system employs the FDMA system for the multiple access. In the FDMA system, one frequency is allocated to each user.
The CT-2 system employs the TDD system (one-frequency time-division bidirectional communication system) as a system for separating a channel (reception channel) from a base station (base unit) to a mobile station (hand set) and a channel (transmission channel) from a mobile station (hand set) to a base station (base unit).
The TDD is a system in which the same frequency is used alternately for transmission and reception in a time division fashion. For example, transmission and reception both using a carrier signal in one frequency band are alternatively switched at every one millisecond.
Since it has been difficult to form a band-pass filter having a sharp cut-off characteristic in a high-frequency circuit block of a mobile station (hand set) of a FDMA/TDD transmitting and receiving apparatus, the transmitting and receiving apparatus has required a double superheterodyne reception system.
SUMMARY OF THE INVENTION
In view of such aspects, it is an object of the present invention to provide an FDMA/TDD transmitting and receiving apparatus which employs a single superheterodyne reception system in a high-frequency circuit block.
More specifically, it is an object of the present invention to provide an FDMA/TDD transmitting and receiving apparatus employing a single superheterodyne reception system which satisfies a standard with respect to spurious emission.
According to an aspect of the present invention, a transmitting and receiving apparatus employing an FDMA system as a multiple access system and employing a TDD system as a bidirectional communication system includes a receiving means for generating a reception data from a reception signal received by an antenna at a timing based on a reception enable signal, an intermediate frequency transmission signal generating means for generating a transmission signal having an intermediate frequency at a timing based on a transmission enable signal having a phase reverse to that of the reception enable signal, a frequency converting means for the transmission signal having the intermediate frequency into a transmission signal having a transmission frequency, a delay means for delaying the transmission enable signal, a signal processing means for subjecting the transmission signal having the transmission frequency to a predetermined signal processing at a timing based on an output from the delay means, and a supply means for supplying an output from the signal processing means to the antenna.
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Jung Min
Maioli Jay H.
Sony Corporation
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