# US 5,349,530 A · Direction detecting device

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- Number: US 5,349,530 A
- Document ID: US5349530A
- Status: Granted
- Kind: A
- Application number: 07/910,244
- Filed: 1992-07-09
- Granted: 1994-09-20
- Earliest claimed: 1991-07-10
- Assignees: Pioneer Electronic Corporation
- Inventors: Satoshi Odagawa
- Web page: https://patentgrep.com/patent/US5349530A

## CPC

- G01S 19/39: the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01C 17/38: Testing, calibrating, or compensating of compasses
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)

## Abstract

A direction detecting device includes the following elements. A position measurement unit receives an electric wave from a satellite and generates first direction data from the electric wave. A geomagnetic sensor generates second direction data. A memory unit, which is coupled to the position measurement unit and the geomagnetic sensor, stores the first direction data and the second direction data respectively obtained at a previous measurement timing. A correction operation unit, which is coupled to the position measurement unit, the geomagnetic sensor and the memory unit, obtains data related to a true magnetic circle from the first direction data and the second direction data stored in the memory unit and the first direction data and the second direction data respectively obtained at a current measurement timing and for correcting an error contained in the current second direction data in accordance with the data related to the true magnetic circle.

## Claims

### Claim 1

A direction detecting device comprising:
position measurement means for receiving an electric wave from a satellite and for generating first direction data from the electric wave;
geomagnetic sensor for generating second direction data;
memory means for storing the first direction data and the second direction data respectively obtained at a previous measurement timing; and
correction operation means, coupled to said position measurement means, said geomagnetic sensor and said memory means, for obtaining data related to a true magnetic circle from the first direction data and the second direction data stored in said storage means and the first direction data and the second direction data respectively obtained at a current measurement timing and for correcting an error contained in the current second direction data in accordance with the data related to the true magnetic circle.

### Claim 2 (depends on 1)

A direction detecting device as claimed in claim 1, wherein said correction operation means comprises means for storing data related to a previous true magnetic circle and for correcting data related to a current true magnetic data by using the stored data related to the previous true magnetic circle.

### Claim 3 (depends on 1)

A direction detecting device as claimed in claim 1, wherein the data related to the true magnetic circle comprises first data indicating coordinates of the true magnetic circle, second data indicating a radius of the true magnetic circle along a major axis thereof, third data indicating a radius along a minor axis thereof, and fourth data indicating an ellipticity of the true magnetic circle.

### Claim 4 (depends on 1)

A direction detecting device as claimed in claim 1, where the satellite comprises a GPS (Global Positioning System) satellite.

### Claim 5 (depends on 2)

A direction detecting device as claimed in claim 2, wherein said correction operation means corrects data related to a current true magnetic circle by mixing the data related to said previous true magnetic circle and the data related to the current magnetic circle with a certain mixing coefficient.