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EP0508401A2
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Direct-conversion FSK receiver with orthogonal demodulation
Assignee: NEC Corp
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Filing: 1992-04-08
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Granted: —
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Expires: 2012-04-08
Abstract
Abstract An FSK receiver is described, which is capable of reducing the loss of sensitivity, caused by cross modulation with interfering signals, which arises in quadrature detection systems. The mixing stage (13-1,13-2) is followed high and low pass filters (31-1,31-2,16-1,16-2) in each of the quadrature channels, and then by a quadrature detector (18). The high pass filters (31-1,31-2) attenuate the demodulated interference signals.
Inventors
- 👤 Yoichiro c/o NEC Corporation Minami
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 12:36
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/10; H04L27/14; H04L27/144; H04L27/152; H04L27/1525
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
83 words
An FSK (Frequency Shift Keying) receiver comprising: mixer means for generating a baseband signal by receiving a modulated wave having been modulated in frequency by a binary digital signal and a local oscillation frequency fed from a local oscillator and coincident with said modulated wave in frequency; band pass filter means to which said baseband signal is applied from said mixer means; and orthogonal detection demodulating means for processing an output signal of said band pass filter means to produce a demodulated signal.
Claim 2
Dependent Claim
43 words
A receiver as claimed in claim 1, wherein said band pass filter means comprises high pass filter means to which said baseband signal is applied and low pass filter means to which an output signal of said high pass filter means is applied.
Claim 3
Dependent Claim
122 words
An FSK (Frequency Shift Keying) receiver comprising: first mixer means for generating first baseband signal in response to a modulated wave having been modulated in frequency by binary signal and a first local frequency signal fed from a local oscillator and coincident with said modulated wave in frequency; second mixer means for generating second baseband signal in response to said modulated wave and a second local frequency signal which is π/2 phase shifted relative to said first local frequency signal; first and second band pass filter means responsive to said first and second baseband signals to generate first filtered signal and second filtered signal, respectively; and orthogonal detection demodulating means for processing said first and second signals to produce a demodulated signal.
Claim 4
Dependent Claim
93 words
A receiver as claimed in claim 3, wherein said first band pass filter means comprises first high pass filter means responsive to said first baseband signal and first low pass filter means responsive to an output signal of said first high pass filter means to generate said first filtered signal, and said second band pass filter means comprises second high pass filter means responsive to said second baseband signal and second low pass filter means responsive to an output signal of said second high pass filter means to generate said second filtered signal.
Claim 5
Dependent Claim
51 words
A receiver as claimed in claim 4, wherein said orthogonal detection demodulating means comprises D-type flip-flop having a data input terminal to which one of said first and second filtered signals is applied and a clock input terminal to which the other of said first and second filtered signal is applied.
References Cited (Backward Citations)
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