MAGNETIC DATA PROCESSING DEVICE, MAGNETIC DATA PROCESSING METHOD, AND MAGNETIC DATA PROCESSING PROGRAM

• US 20090172505A1
• Filed: 12/23/2008
• Published: 07/02/2009
• Est. Priority Date: 12/28/2007
• Status: Active Grant

• Current Assignee: Yamaha Corporation
• Original Assignee: Yamaha Corporation
• Inventors: HANDA, IBUKI
• Granted Patent: US 8,413,034 B2
• Time in Patent Office: Days
• US Class Current: 714/799
• CPC Class Codes: G01R 33/1207 Testing individual magnetic storage devices, e.g. records carriers or digital storage elements functional testing G06F11/00, G06F11/28

Abstract

In a magnetic data processing device, an input part sequentially receives magnetic data output from a magnetic sensor. A storage part stores a plurality of the magnetic data as a data set of statistical population. An index derivation part derives a distribution index of the data set of the statistical population. A reliability determination part determines whether or not reliability of the data set of the statistical population is acceptable based on the distribution index and a decision criterion. A decision criterion setting part increases strictness of the decision criterion when the reliability determination part determines that the reliability of the data set of the statistical population is acceptable, and decreases the strictness of the decision criterion when the reliability determination part determines that the reliability of the data set of the statistical population is unacceptable.

Claims

1. A magnetic data processing device comprising:

an input part that sequentially receives magnetic data output from a magnetic sensor;

a storage part that stores a plurality of the magnetic data as a data set of statistical population;

an index derivation part that derives a distribution index of the data set of the statistical population;

a reliability determination part that determines whether or not reliability of the data set of the statistical population is acceptable based on the distribution index and a decision criterion; and

a decision criterion setting part that increases strictness of the decision criterion when the reliability determination part determines that the reliability of the data set of the statistical population is acceptable and decreases the strictness of the decision criterion when the reliability determination part determines that the reliability of the data set of the statistical population is unacceptable.

2. The magnetic data processing device according to claim 1, wherein the decision criterion setting part changes the decision criterion in a stepwise manner each time the reliability determination part determines whether or not the reliability of the data set of the statistical population is acceptable.

3. The magnetic data processing device according to claim 2, wherein the decision criterion setting part limits a range of the decision criterion such that the decision criterion is changed stepwise within the limited range.

4. The magnetic data processing device according to claim 2, wherein the decision criterion setting part fixes the decision criterion when the decision criterion converges within a predetermined range.

5. The magnetic data processing device according to claim 1, wherein the index derivation part derives the distribution index as a function of variance of the data set of the statistical population.

6. The magnetic data processing device according to claim 1, wherein the index derivation part derives the distribution index as a function of principal values that characterize distribution of the data set of the statistical population.

7. The magnetic data processing device according to claim 1, wherein the index derivation part derives the distribution index as a function of a central angle that represents an angular range of distribution of the data set of the statistical population.

8. The magnetic data processing device according to claim 1, further comprising an offset derivation part that derives an offset of the magnetic data based on the data set of the statistical population whose reliability has been determined to be acceptable.

9. The magnetic data processing device according to claim 1, wherein the decision criterion setting part sets the decision criterion as a single threshold value, and the reliability determination part determines the reliability of the data set of the statistical population based on comparison of a value of the distribution index with the single threshold value.

10. The magnetic data processing device according to claim 1, further comprising the magnetic sensor that outputs the magnetic data.

11. A navigation apparatus comprising:

a magnetic sensor that outputs magnetic data;

an input part that sequentially receives the magnetic data output from the magnetic sensor;

a storage part that stores a plurality of the magnetic data as a data set of statistical population;

an index derivation part that derives a distribution index of the data set of the statistical population;

a reliability determination part that determines whether or not reliability of the data set of the statistical population is acceptable based on the distribution index and a decision criterion;

a decision criterion setting part that increases strictness of the decision criterion when the reliability determination part determines that the reliability of the data set of the statistical population is acceptable and decreases the strictness of the decision criterion when the reliability determination part determines that the reliability of the data set of the statistical population is unacceptable;

an offset derivation part that derives an offset of the magnetic data based on the data set of the statistical population whose reliability has been determined to be acceptable;

a correction part that corrects the magnetic data based on the offset; and

an orientation notification part that provides notification of an orientation based on the corrected magnetic data.

12. A magnetic data processing method comprising:

sequentially receiving magnetic data output from a magnetic sensor;

storing a plurality of the magnetic data as a data set of statistical population;

deriving a distribution index of the data set of the statistical population;

determining whether or not reliability of the data set of the statistical population is acceptable based on the distribution index and a decision criterion; and

increasing strictness of the decision criterion when it is determined that the reliability of the data set of the statistical population is acceptable and decreasing the strictness of the decision criterion when it is determined that the reliability of the data set of the statistical population is unacceptable.

13. A machine readable medium containing a magnetic data processing program causing a computer to execute a process of:

sequentially receiving magnetic data output from a magnetic sensor;

storing a plurality of the magnetic data as a data set of statistical population;

deriving a distribution index of the data set of the statistical population;

determining whether or not reliability of the data set of the statistical population is acceptable based on the distribution index and a decision criterion; and

increasing strictness of the decision criterion when it is determined that the reliability of the data set of the statistical population is acceptable and decreasing the strictness of the decision criterion when it is determined that the reliability of the data set of the statistical population is unacceptable.