Modulators – Amplitude modulator – Nonlinear device controlled by modulating signal
Patent
1980-07-30
1982-07-06
Grimm, Siegfried H.
Modulators
Amplitude modulator
Nonlinear device controlled by modulating signal
329 50, 329105, 329112, 329126, 332 22, 332 23R, 375 62, 375 89, 375110, H04L 2712, H04L 2714
Patent
active
043385796
ABSTRACT:
A Frequency Shift Offset Quadrature (FSOQ) signal which is a constant envelope frequency-shift keyed version of an offset quaternary phase shift keyed (O-QPSK) transmission is provided. A technique for generating an FSOQ signal in a manner similar to O-QPSK by modulating offset quadrature channels with selectable pulse shapes which yields the desired 3-tone continuous phase FSK approximation of O-QPSK is disclosed. Receiver synchronization circuits are also provided which enable FSOQ to be detected as a special case of O-QPSK, whereby the detection performance of synchronous coherent QPSK, rather than the relatively inferior performance of FSK detection, is obtained. FSOQ provides a constant envelope and requires less bandwidth than minimum shift keying (MSK).
REFERENCES:
patent: 4006418 (1977-02-01), Liskov et al.
patent: 4097813 (1978-06-01), Otani et al.
patent: 4158105 (1979-06-01), Otani et al.
patent: 4281412 (1981-07-01), Wissel et al.
Communications Satelite Corp.
Grimm Siegfried H.
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