Telecommunications – Receiver or analog modulated signal frequency converter – Plural receivers
Patent
1991-01-03
1993-11-16
Eisenzopf, Reinhard J.
Telecommunications
Receiver or analog modulated signal frequency converter
Plural receivers
4552452, 455273, 4552761, H04B 1702
Patent
active
052631800
ABSTRACT:
In a space diversity reception system, a plurality of receiving circuits, each of which is connected to respective antenna, outputs a first type signal having a level which varies in accordance with the radio frequency signal level input to the receiving circuit. An automatic gain-controlled amplifier amplifies the first type signal so as to output a second type signal having a substantially constant level. A phase control circuit detects a phase difference between the second type signal output from each of the automatic gain-controlled amplifiers and controls the phase difference in each of the first type signals to be null. A combining circuit combines the signals, whose levels are respectively following the input radio frequency signal levels, picked up from each of an inter-stage in the receiving circuits, an output of the combining circuit is the output of the space diversity system. This circuit configuration allows an employment of a less expensive automatic gain-controlled amplifier requiring less severe characteristics. Thus, a circuit for adjusting the input levels to the combining circuit can be avoided, accordingly, a multi-level quadrature amplitude modulation signal having amplitude-modulated component can be received.
REFERENCES:
patent: 2975275 (1961-03-01), Adams
patent: 3540055 (1970-11-01), Takagi
patent: 4386435 (1983-05-01), Ulmer et al.
Patent Abstracts of Japan, vol. 13, No. 92, Mar. 3, 1989.
Hirayama Eiichi
Umino Isamu
Eisenzopf Reinhard J.
Faile Andrew
Fujitsu Limited
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