Telecommunications – Receiver or analog modulated signal frequency converter – Local control of receiver operation
Patent
1988-09-23
1990-09-04
Eisenzopf, Reinhard J.
Telecommunications
Receiver or analog modulated signal frequency converter
Local control of receiver operation
455234, 455304, 455314, H04L 2714
Patent
active
049550780
ABSTRACT:
A frequency difference detector (FDD) implemented as a balanced quadricorrelator has an automatic gain control system (68) having inputs capacitively coupled to the quadrature related, baseband frequency paths from the front end mixers (12,14). The a.g.c. system (68) has quadrature related mixers (78,80) coupled to said inputs for frequency up-converting the baseband signals to an intermediate frequency. The IF signals from the mixers are summed in a summing circuit (82) and subsequently squared in a squaring circuit (86). Any ripple in the output of the squaring circuit is removed by low pass filtering to produce a d.c. control signal which is applied to gain controlled amplifiers (22,24) present in said baseband frequency paths in order to render the output (V.sub.o) of the FDD less sensitive to variations in the input signal (V.sub.i).
REFERENCES:
patent: 3160815 (1964-12-01), Ford et al.
patent: 4200871 (1980-04-01), Roeder et al.
patent: 4677690 (1987-06-01), Reed
patent: 4736390 (1988-04-01), Ward et al.
patent: 4736392 (1988-04-01), Kammeyer et al.
Eisenzopf Reinhard J.
Treacy David R.
U.S. Philips Corporation
Urban Edward
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