Telecommunications – Receiver or analog modulated signal frequency converter – Signal selection based on frequency
Patent
1985-07-02
1987-09-22
Ng, Jin F.
Telecommunications
Receiver or analog modulated signal frequency converter
Signal selection based on frequency
455209, 455260, 455265, 455316, 375 83, 375 97, 375120, 331 22, H04B 126
Patent
active
046960562
ABSTRACT:
A frequency converting circuit converts an input frequency into a desired frequency. To obtain the desired frequency, a first frequency converter converts the input frequency, by using an output frequency of a first local oscillator, into an intermediate frequency. The first local oscillator is a voltage controlled oscillator as a part of a phase locked loop circuit. A second frequency converter converts the intermediate frequency into the desired frequency by using an output frequency of a second local oscillator. A phase comparing circuit compares the phase of the output signal of the second frequency converter with that of the output signal of the first local oscillator. The phase comparing circuit is contained in the phase locked loop circuit. The result of the comparison is used for controlling the oscillating frequency of the first local oscillator.
REFERENCES:
patent: 4303893 (1981-12-01), Goldberg
patent: 4403345 (1983-09-01), Granek et al.
patent: 4451930 (1984-05-01), Chapman et al.
IEEE Transactions on Communications, vol. COM-25, No. 10, 10/77, "Heterodyne Phase Locked Loops-Revisited", by Biswas et al.
Kabushiki Kaisha Toshiba
Ng Jin F.
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