Methods and apparatus for delay free phase shifting in correcting PLL phase offset
First Claim
1. An apparatus to eliminate a frequency-dependent differential phase shift, Δ
- θ
(f), between a double sideband suppressed carrier modulated angular rate information signal and its sinusoidal demodulation reference signal in a gyroscope angular rate sensing circuit, the circuit including a demodulation reference source, said apparatus comprising;
a demodulator;
a phase shifter in a demodulation reference signal path, the demodulation reference signal path being between the signal reference source and said demodulator, said phase shifter configured to adjust a phase of the sinusoidal demodulation reference signal;
a phase locked loop (PLL) comprising a phase detector, a servo equalizer, and a dual-frequency, numerically controlled oscillator, said PLL configured to provide a demodulation signal based on the phase shifted demodulation reference signal; and
a phase shift command source configured to provide an input to said phase shifter to command an appropriate phase adjustment.
1 Assignment
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Accused Products
Abstract
An apparatus eliminates a differential phase shift, Δθ(f), between a double sideband suppressed carrier modulated angular rate information signal and its sinusoidal demodulation reference signal in a gyroscope angular rate sensing circuit including a signal reference source. The apparatus includes a demodulator, a phase shifter in a demodulation reference signal path, the demodulation reference signal path being between the signal reference source and the demodulator. The phase shifter is configured to adjust a phase of the sinusoidal demodulation reference signal. A phase locked loop (PLL) includes a phase detector, a servo equalizer, and a dual-frequency, numerically controlled oscillator. The PLL is configured to provide a demodulation signal based on the phase shifted demodulation reference signal, and a phase shift command source is configured to provide an input to the phase shifter to command an appropriate phase adjustment.
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Citations
21 Claims
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1. An apparatus to eliminate a frequency-dependent differential phase shift, Δ
- θ
(f), between a double sideband suppressed carrier modulated angular rate information signal and its sinusoidal demodulation reference signal in a gyroscope angular rate sensing circuit, the circuit including a demodulation reference source, said apparatus comprising;
a demodulator;
a phase shifter in a demodulation reference signal path, the demodulation reference signal path being between the signal reference source and said demodulator, said phase shifter configured to adjust a phase of the sinusoidal demodulation reference signal;
a phase locked loop (PLL) comprising a phase detector, a servo equalizer, and a dual-frequency, numerically controlled oscillator, said PLL configured to provide a demodulation signal based on the phase shifted demodulation reference signal; and
a phase shift command source configured to provide an input to said phase shifter to command an appropriate phase adjustment. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for eliminating a differential phase shift, Δ
- θ
, between a double sideband suppressed carrier modulated information signal and its sinusoidal demodulation reference signal in a circuit, the circuit including a demodulator, a phase shift command source and a phase shifter in a reference signal path between a signal reference source and the demodulator, said method comprising;
generating an appropriate phase adjustment command from the phase shift command source to the phase shifter; and
adjusting a phase of the sinusoidal demodulation reference signal with the phase shifter. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. An angular rate measurement system comprising:
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a gyroscope configured to sense an angular rate input and provide a modulated angular rate information signal and a sinusoidal demodulation reference signal;
a demodulator configured to demodulate a signal representative of the angular rate information signal;
a phase shifter configured to adjust a phase of a signal representative of the sinusoidal demodulation reference signal;
a phase locked loop configured to provide a demodulation signal to said demodulator, the demodulation signal based on the phase adjusted demodulation reference signal; and
a phase shift command source configured to provide a frequency based input to said phase shifter to enable an appropriate phase adjustment of the demodulation reference signal, the phase adjustment eliminating a frequency dependent differential phase shift, Δ
θ
(f), between the modulated angular rate information signal and the sinusoidal demodulation reference signal. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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Specification