Automatic magnetic compass correction

• US 4,091,543 A
• Filed: 06/17/1976
• Issued: 05/30/1978
• Est. Priority Date: 06/17/1976
• Status: Expired due to Term

• Current Assignee: Laitram LLC
• Original Assignee: Laitram LLC
• Inventors: Lapeyre, James M.
• Primary Examiner(s): Haroian, Harry N.
• Application Number:
  US05/697,194
• Time in Patent Office: 712 Days
• Field of Search: 33/356, 33/357, 33/362, 33/326
• US Class Current: 33/356
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses

Abstract

Method and apparatus for providing automatic correction of deviation errors in a magnetic compass. Data representing deviation corrections for respective compass headings are stored in memory and in response to a digital signal from the magnetic compass representing an indicated heading, the corresponding correction is provided from memory to yield a output signal representing actual heading and corrected for deviation error.

Claims

1. Apparatus for providing a deviation-corrected output signal representative of an actual compass heading comprising:

a magnetic compass providing a digital output signal representative of an indicated compass heading;

means for storing deviation-corrected signals representative of the actual heading of the compass for each of a plurality of different indicated headings

and for providing the stored deviation-corrected signal corresponding with the indicated compass heading in response to the output signal from the compass; and

means responsive to the provided deviation-corrected signal for producing a deviation-corrected output signal representative of the actual compass heading.

2. Apparatus for providing a deviation-corrected output signal representative of an actual compass heading comprising:

a magnetic compass providing a digital output signal representative of an indicated compass heading;

a read-only memory for storing deviation-corrected signals representative of the actual heading of the compass for each of a plurality of different indicated headings and for providing

the stored deviation-corrected signal corresponding with the indicated compass heading in response to the output signal from the compass; and

means responsive to the provided deviation-corrected signal for producing a deviation-corrected output signal representative of the actual compass heading.

3. Apparatus for providing a deviation-corrected output signal representative of an actual compass heading comprising:

a magnetic compass providing an output signal representative of an indicated compass heading;

means for storing deviation-correction signals representative of the deviation of the compass for each of a plurality of different indicated headings and for providing

the stored deviation-correction signals corresponding with the indicated compass heading in response to the output signal from the compass; and

means for combining the compass output signal and the provided deviation-correction signal to produce the deviation-corrected output signal representative of the actual compass heading.

4. The apparatus of claim 3 wherein the means for storing comprises a read-only memory containing data representative of compass deviation for each of a plurality of different compass headings.

5. The apparatus of claim 4 further comprising means for providing signals representative of magnetic variation;

and wherein the producing means is further operative to combine the signals representative of magnetic variation with the compass output signal and the retrieved deviation-correction signal to produce a deviation-correction output signal representative of the actual heading of the compass with respect to true north.

6. The apparatus of claim 4 further including a digital readout responsive to the deviation-corrected output signal for display of actual compass heading.

7. A method for providing deviation-correction signals for a magnetic compass, comprising the steps of:

storing deviation-correction signals representative of the deviation of the compass for each of a plurality of different headings;

providing a digital compass output signal from a compass representative of an indicated compass heading;

retrieving in response to the output signal from the compass the stored deviation-correction signal corresponding to the indicated compass heading; and

combining the compass output signal and the retrieved deviation-corrected signal to produce a deviation-corrected output signal representative of the actual compass heading.

8. The method of claim 7 further including the step of providing a signal representative of magnetic variation:

and wherein the step of combining further includes combining the signal representative of magnetic variation with the compass output signal and the retrieved deviation-correction signal to produce an output signal representative of the actual heading of the compass with respect to true north.