Vehicle-mounted satellite signal receiving system
First Claim
1. A vehicle-mounted satellite signal receiving system comprising:
- an antenna mounted on a vehicle;
a gyro sensor for detecting the rotational angular velocity of said vehicle and outputting an output signal, said output signal having an offset error and a sensitivity error;
a sensitivity error correcting means for correcting the output signal of said gyro sensor to make up for said sensitivity error of said output signal separately from said offset error by multiplying said gyro sensor output signal by a sensitivity coefficient and outputting a corrected gyro sensor output signal;
gyro tracking means for controlling the bearing of said antenna according to said corrected gyro sensor output signal; and
sensitivity coefficient correcting means for determining whether a correction of said sensitivity error of the gyro sensor by said sensitivity error correcting means is appropriate when a received power level of a satellite signal received by said antenna is reduced from a previous level, and correcting said sensitivity coefficient it if is appropriate to do so.
1 Assignment
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Accused Products
Abstract
A vehicle-mounted satellite signal receiving system adopting a satellite tracking system combining gyro tracking and hybrid tracking is disclosed which can correct a sensitivity coefficient for correcting a gyro sensor output signal to make up for a sensitivity error, even when a drift is produced in the sensitivity error. In this system, gyro tracking is caused when the received power level is above a threshold power level. The gyro tracking is done by determining the angular velocity ω of an antenna as ω=-(ωG×ΔSB+ωG from a value obtained by inverting the sign of the product of a gyro tracking angular velocity ωG and a sensitivity coefficient ΔSB for dealing with the sensitivity error and a predetermined offset error correction value ωG and setting the antenna to ω. When ΔSB is inaccurate and a sensitivity error is generated in the gyro sensor output signal, the received power level is reduced. When the received power level becomes lower than a threshold power level LB, the sensitivity coefficient is corrected on the basis of the sense of the angular velocity ωS in the hybrid tracking (step tracking) and in the gyro tracking.
17 Citations
15 Claims
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1. A vehicle-mounted satellite signal receiving system comprising:
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an antenna mounted on a vehicle; a gyro sensor for detecting the rotational angular velocity of said vehicle and outputting an output signal, said output signal having an offset error and a sensitivity error; a sensitivity error correcting means for correcting the output signal of said gyro sensor to make up for said sensitivity error of said output signal separately from said offset error by multiplying said gyro sensor output signal by a sensitivity coefficient and outputting a corrected gyro sensor output signal; gyro tracking means for controlling the bearing of said antenna according to said corrected gyro sensor output signal; and sensitivity coefficient correcting means for determining whether a correction of said sensitivity error of the gyro sensor by said sensitivity error correcting means is appropriate when a received power level of a satellite signal received by said antenna is reduced from a previous level, and correcting said sensitivity coefficient it if is appropriate to do so. - View Dependent Claims (3, 4, 5, 9, 10, 11, 12, 14, 15)
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2. A vehicle-mounted satellite signal receiving system comprising:
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a vehicle-mounted antenna; a gyro sensor for detecting the rotational angular velocity of a vehicle and outputting an output signal, said output signal having an offset error and a sensitivity error, a sensitivity error correcting means for correcting the output signal of said gyro sensor to make up for a sensitivity error of said output signal of signal gyro sensor by multiplying said gyro sensor output signal by a sensitivity coefficient and outputting a corrected gyro sensor output signal; gyro tracking means for controlling the bearing of said antenna according to said corrected gyro sensor output signal when a received power level of a satellite signal received by said antenna is above a first predetermined power level; step tracking means for controlling the bearing of said antennas the control provided by said step tracking means enabling said received power level of said satellite signal to be increased when it is below a second predetermined power level; and sensitivity coefficient correcting means for comparing, when the control of the bearing of said antenna by said step tracking means results from the reduction of said received power level being below said second predetermined power level, an antenna rotation direction during the control by said step tracking means and the antenna rotation direction during the control by said gyro tracking means, and correcting said sensitivity coefficient by a predetermined amount of reduction if the two antenna rotation directions are different, and correcting said sensitivity coefficient by a predetermined amount of increment if the two antenna rotation directions are the same. - View Dependent Claims (6, 7, 8, 13)
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Specification