Telecommunications – Receiver or analog modulated signal frequency converter – Noise or interference elimination
Patent
1997-04-14
2000-08-29
Eisenzopf, Reinhard J.
Telecommunications
Receiver or analog modulated signal frequency converter
Noise or interference elimination
455334, H04B 110
Patent
active
061120707
ABSTRACT:
A receiving wave containing a desired signal and received through an antenna is inputted to an interstage band-pass filter 4 after the component outside a receiving band of the receiving wave has been attenuated by a receiving band-pass filter 2a. A phase locked loop circuit 9 outputs a frequency control voltage corresponding to a selected channel to a voltage control oscillator 8 and also outputs this frequency control voltage to an interstage band-pass filter 4 as a band control voltage thereof. The voltage control oscillator 8 generates a local carrier wave in response to the frequency control voltage. The interstage variable band-pass filter 4 has a passing band width which is a little wider than channel band width and varies its passing band in response to the band control voltage so as to include the selected channel, thereby attenuating the component outside the passing band of the receiving wave inputted from the low noise amplifier 3 and then inputs the receiving wave to a mixer 5. Accordingly, if a frequency which causes a single-signal interference is located in the receiving band apart from the selected channel frequency by a half of the intermediate frequency, the interference wave of this frequency can be attenuated.
REFERENCES:
patent: 5822687 (1998-10-01), Bickley et al.
patent: 5963856 (1999-10-01), Kim
Andou Hiroshi
Katsuyama Tsutomu
Banks-Harold Marsha D.
Eisenzopf Reinhard J.
OKI Electric Industry Co., Ltd.
Volentine, LLP Jones
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