Telecommunications – Receiver or analog modulated signal frequency converter – Frequency or phase modulation
Patent
1979-02-06
1980-11-25
Ng, Jin F.
Telecommunications
Receiver or analog modulated signal frequency converter
Frequency or phase modulation
455315, H04B 126
Patent
active
042362520
ABSTRACT:
A first intermediate frequency amplifier stage which executes the amplitude limiting operation of a double-converting FM tuner employing the integrated circuit technology is constructed in the form of an integrated circuit. An output signal of the first intermediate frequency amplifier stage is put into a square pulse waveform on the basis of the amplitude limiting operation, and therefore has higher harmonic components of high frequencies. When the higher harmonic components are injected into a second mixer circuit in a second frequency converter circuit, various higher harmonic components which have frequencies higher than a second intermediate frequency appear at the output of the second mixer conduit. When the higher harmonic components at the output of the second mixer circuit are injected into an FM demodulator circuit, beat trouble is induced. The second frequency converter circuit is also constructed in the form of an integrated circuit, and filter means to pass the fundamental waves of a first intermediate frequency signal and to reject the higher harmonic frequency components thereof is connected between the output of the first intermediate frequency amlifier stage executing the amplitude limiting operation and the input of the second mixer circuit, whereby the beat trouble can be prevented.
REFERENCES:
patent: 3473133 (1969-10-01), Hummel
patent: 3641441 (1972-02-01), Gunn et al.
patent: 3665507 (1972-05-01), Peil
patent: 3673499 (1972-06-01), Avins et al.
patent: 3939429 (1976-02-01), Lohn et al.
patent: 4091330 (1978-05-01), Hidaka
patent: 4122394 (1978-10-01), Fukushima et al.
"Denpa Kagaku", (Electric Wave Science), Jan. 1977, vol. 532, pp. 161-165.
Ienaka Masanori
Kominami Yasuo
Miyamoto Yukihiko
Wada Takeshi
Yamada Tsuneo
Hitachi , Ltd.
Ng Jin F.
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