Telecommunications – Transmitter and receiver at same station – With transmitter-receiver switching or interaction prevention
Patent
1992-09-17
1996-09-03
Eisenzopf, Reinhard J.
Telecommunications
Transmitter and receiver at same station
With transmitter-receiver switching or interaction prevention
455 76, 455102, 370 29, 370 953, H04B 144
Patent
active
055533175
ABSTRACT:
In a radio telephone apparatus of the TDMA/TDD system, signal transmission and reception are conducted by use of carriers having an identical frequency. This leads to a problem that the transmission intermediate frequency carrier and the transmission RF carrier enter the receiver section in an identical housing, thereby causing a cochanncl interference. To overcome this difficulty, there is disposed a frequency division modulator including a frequency divider for dividing by four a local signal having a frequency which is four times that of the intermediate frequency to obtain a carrier having a frequency shifted from that of the local signal by 90.degree.. Signal to be modulated is subjected to an orthogonal modulation according to the carrier wave to produce an intermediate frequency carrier. The operation of the modulator is stopped in a signal reception state to prevent the intermediate frequency carrier undergone the orthogonal modulation from being produced.
REFERENCES:
patent: 4430756 (1984-02-01), Dolman et al.
patent: 4476575 (1984-10-01), Franke et al.
patent: 4825436 (1989-04-01), Kobayashi et al.
patent: 4853972 (1989-08-01), Ueda et al.
patent: 4942570 (1990-07-01), Kotzin et al.
patent: 5222253 (1993-06-01), Heck
"The GSM radio interface" by M. R. L. Hodges, Br. Telecom Technol. J. vol. 8, No. 1, Jan. 1990, pp. 31-43.
Eisenzopf Reinhard J.
NEC Corporation
Sobutka Philip J.
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