Apparatus and method for determining pitch and azimuth from satellite signals
First Claim
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1. A navigational apparatus suitable for use with a plurality of satellites, each satellite transmitting a positional signal, the signal being carrier modulated with code and date, said navigational device comprising:
- a primary antenna for acquiring a set of primary positional signals from the plurality of satellites;
a secondary antenna disposed in fixed relationship to said primary antenna, said secondary antenna for acquiring a set of secondary positional signals from the plurality of satellites;
receiver means in electrical communication with at least one of said primary and secondary antennas, said receiver means for inputting at least one said set of primary or secondary positional signals and for outputting post-correlation data derived from said at least one set of primary or secondary positional signals;
means for deriving a carrier-to-noise ratio for each said positional signal from said post correlation data;
means for deriving multipath error estimates from said signal to noise ratios;
means for reducing carrier ambiguity sets according to pre-determined criteria;
means for deriving an azimuth or pitch estimate using said multipath error estimates to optimally generate an azimuth and pitch estimate.
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Abstract
A navigational apparatus includes a receiver, two antennas, and a computational unit to receive satellite positional signals and provides corrected position, azimuth, and pitch readings. The computational unit: determines differences in the signal carrier measurements output by the receiver; rejects or accepts carrier ambiguity candidates based on predefined criteria; and estimates multipath on successive pairs of carrier observations to obtain the corrected readings.
25 Citations
12 Claims
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1. A navigational apparatus suitable for use with a plurality of satellites, each satellite transmitting a positional signal, the signal being carrier modulated with code and date, said navigational device comprising:
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a primary antenna for acquiring a set of primary positional signals from the plurality of satellites;
a secondary antenna disposed in fixed relationship to said primary antenna, said secondary antenna for acquiring a set of secondary positional signals from the plurality of satellites;
receiver means in electrical communication with at least one of said primary and secondary antennas, said receiver means for inputting at least one said set of primary or secondary positional signals and for outputting post-correlation data derived from said at least one set of primary or secondary positional signals;
means for deriving a carrier-to-noise ratio for each said positional signal from said post correlation data;
means for deriving multipath error estimates from said signal to noise ratios;
means for reducing carrier ambiguity sets according to pre-determined criteria;
means for deriving an azimuth or pitch estimate using said multipath error estimates to optimally generate an azimuth and pitch estimate. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for deriving an attitude, pitch or positional reading for a vessel or flight vehicle from signals transmitted by a plurality of positional satellites, said method comprising the steps of:
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acquiring a set of primary positional signals from the plurality of satellites via a primary antenna;
acquiring a set of secondary positional signals from the plurality of satellites via a secondary antenna;
deriving post-correlation data from said sets of primary and secondary positional signals;
deriving a signal-to-noise ratio for each said positional signal from said post correlation data;
deriving a multipath estimate from said signal to noise ratios; and
estimating an azimuth or pitch reading from said multipath estimate. - View Dependent Claims (9, 10, 11, 12)
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Specification