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US 6,748,030 B2Granted
Differential phase demodulator incorporating 4th order coherent phase tracking
AssigneeNorthrop Grumman Corporation
InventorMichael H. Myers
Life of this patent
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AssigneeNorthrop Grumman Corporation
InventorMichael H. Myers
Estimating the term…
Demodulating a DPSK encoded data signal. The received signal has a symbol tracking value determined in a synchronization circuit. Doppler error in the signal is estimated. The signal, the symbol tracking value, and the estimated Doppler error are applied to a demodulator within which the signal is multiplied by a signal at a frequency which is the negative of the estimated Doppler error to remove that Doppler error. The resulting signal is filtered and decimated and normalized to generate the arctangent of the in-phase and quadrature components of the baseband signal. This arctangent signal is stripped of phase angle modulation and applied through loops to remove derivatives of the input phase signal. The arctangent and the resulting angles are mapped in a nearest neighbor map circuit, and the difference between successive angles is applied to a gray code to binary mapping circuit which detects the encoded data.
A method of demodulating a received radio frequency signal, including a baseband signal with D*PSK encoded data, where * is an integer and where the baseband signal has a frequency of 0 Hz, to obtain the encoded data, said method comprising:
A system for demodulating a received radio frequency signal, including a baseband signal with D*PSK encoded data, where * is an integer and where the received signal is expected to be at a known frequency, to obtain the encoded data, said system comprising:
Dependencies are inferred from the claim text.