| 摘要 |
The invention provides navigational apparatus in which the power supply for a detector measuring the magnetic heading of the vehicle to which the apparatus is fitted, is effectively isolated from the power supply for other components of the apparatus and is stabilised with the result that the overall accuracy of the apparatus is improved considerably even though the power supply for said other components may be relatively unstable. A preferred arrangement comprises gyroscopic means operable to detect changes in heading of the vehicle and produce an electrical output signal in accordance therewith, drive means operable to drive a shaft of a heading indicator in response to the output signal from the gyroscopic means, a detector operable to measure the magnetic heading of the vehicle and to produce an A.C. output signal in accordance therewith, a demodulator operable to produce a D.C. output signal from the A.C. output signal of the detector, logic circuitry to produce a pulsed output signal in response to the D.C. output signal from the demodulator, and a stepper motor to which is applied the pulsed output signal from the logic circuitry and which drives the shaft of the heading indicator to compensate the latter for changes in the magnetic heading of the vehicle, electrical power for the detector and the demodulator being derived from a first stablized A.C. supply which is effectively voltage and frequency independent of a second A.C. supply for at least the gyroscopic device and the drive means.
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