Pulse or digital communications – Receivers – Angle modulation
Patent
1997-06-20
1999-09-07
Chin, Stephen
Pulse or digital communications
Receivers
Angle modulation
375344, 329302, 455209, 455257, 455260, 455314, H04L 2714, H04L 2706, H03D 300, H04B 126
Patent
active
059498307
ABSTRACT:
In a direct conversion receiver with an AFC function comprising a local oscillation circuit constituted by a synthesizer, the local oscillation frequency is prevented from radiating as an interfere wave against the receiver per se so as not to reduce the reception characteristic, and it is made possible to reduce the value of the multiplication factor N of a multiplier in the synthesizer without making the frequency of a VCO per se high. Specifically, a first local oscillation signal 12 obtained by multiplying an output frequency F.sub.X of a reference crystal oscillation circuit portion 8 of a synthesizer circuit section 7 by M by a multiplier 11 is mixed with an FSK modulation signal 1 in a first mixer 4. In a second mixer 5, the thus mixed signal is further mixed with a second local oscillation signal 13 obtained by multiplying an output frequency F.sub.V of a synthesizer 9 by N by a multiplier 10. The frequencies of the first and second local oscillation signals are selected so as to establish the condition M.multidot.F.sub.X >N.multidot.F.sub.V so that the multiplication factor N of the multiplier 10 can be made small.
REFERENCES:
patent: 4817197 (1989-03-01), Shimizu et al.
patent: 5115515 (1992-05-01), Yamamoto et al.
patent: 5361407 (1994-11-01), Sawada et al.
patent: 5402446 (1995-03-01), Minami
patent: 5857004 (1999-01-01), Abe
Chin Stephen
Deppe Betsy L.
Matsushita Electric - Industrial Co., Ltd.
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