Vehicle-mounted satellite signal receiving apparatus
First Claim
1. A vehicle mounted satellite signal receiving apparatus comprising:
- an antenna mounted on a vehicle;
a gyro sensor for detecting an angular velocity of azimuth rotation of said vehicle;
offset error correcting means for adding a correction value, which is used to correct an offset error of an output signal of said gyro sensor, to said output signal and for outputting a corrected output signal of said gyro sensor, which is derived from said correction of said offset error;
gyro tracking means for controlling direction of said antenna based on said corrected output signal of said gyro sensor when a reception level of a satellite signal is greater than or equal to a first predetermined value;
step tracking means for controlling a direction of said antenna so as to raise said reception level when said reception level is less than said first predetermined value; and
revising means for revising said correction value by adding a revision value, which is in a same direction as a direction of control caused by said step tracking means, to said correction value when said reception level is less than said first predetermined value and said step tracking means commences controlling said direction of said antenna.
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Accused Products
Abstract
In a vehicle mounted satellite signal receiving apparatus which adopts a satellite tracking system combining a gyro tracking with a hybrid tracking, there is provided a device which can revise an offset error correction value of a gyro sensor, even if there is a drift in the offset error. In this device, gyro tracking is performed when a reception level is a threshold value LC or more. The gyro tracking is performed by setting an antenna at an angular velocity ω, which is derived from an equation,ω=-ωG+ΔωG, where -ωG is a value resulted from conversion of sign for gyro angular velocity ωG, and ΔωG is a prescribed offset error correction value. A reception level declines if the offset error correction value ΔωG deviates and therefore an apparent offset error arises in the gyro sensor. When the reception level declines below a threshold value LB, the aforementioned offset error correction value ΔωG is revised, basing on the direction of an angular velocity ωS which is used in the hybrid tracking (or step tracking).
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Citations
16 Claims
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1. A vehicle mounted satellite signal receiving apparatus comprising:
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an antenna mounted on a vehicle; a gyro sensor for detecting an angular velocity of azimuth rotation of said vehicle; offset error correcting means for adding a correction value, which is used to correct an offset error of an output signal of said gyro sensor, to said output signal and for outputting a corrected output signal of said gyro sensor, which is derived from said correction of said offset error; gyro tracking means for controlling direction of said antenna based on said corrected output signal of said gyro sensor when a reception level of a satellite signal is greater than or equal to a first predetermined value; step tracking means for controlling a direction of said antenna so as to raise said reception level when said reception level is less than said first predetermined value; and revising means for revising said correction value by adding a revision value, which is in a same direction as a direction of control caused by said step tracking means, to said correction value when said reception level is less than said first predetermined value and said step tracking means commences controlling said direction of said antenna. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification