Autonnic A5022 Kullanıcı Kılavuzu - Sayfa 7

Denizcilik Ekipmanları Autonnic A5022 için çevrimiçi göz atın veya pdf Kullanıcı Kılavuzu indirin. Autonnic A5022 12 sayfaları. Fluxgate compass

1/6 of a degree. At the same time the A5022 would be also sending the NMEA data

to a precision of 1/10 of a degree.

Clock

Data

Calibration

4.1 Why the compass needs calibrating

When any compass is installed the magnetic characteristics of the whole installation

affect the way the Earth's field reaches the detector inside the device. Each

individual installation will be different and so the A5022 is equipped with an auto-

calibration routine which corrects for these installation distortions.

A NMEA-0183 command can be sent to initiate the process.

Switch 1 can be pressed to start it.

There are two compass calibration techniques in common use:

Constant angular velocity

Double rotation without constant velocity.

The A5022 uses the first method. The process consists of rotating the whole installation

in the Earth's field so that both permanent magnets and induced magnets are

corrected. The method used is the single turn at a constant rate and this rate

should be in range 60 to 180 seconds for the full 400 degrees needed. The whole

arrangement is turned at constant angular velocity because the method relies on

applying a correction when the heading measured is uneven with time.

The second method is not used in the A5022. Autonnic has evaluated the method which

uses a mathematical model of an ideal compass and treats errors as arising from

distortion due to magnetic objects. The ideal error plot of the field vector would be a

circle with no offset from the origin. Permanent magnets ('hard') have the effect of

Duration of data is 16 clocks each

480µs

high =low=30µ s. Total = 480µs.

100ms minimum

Fig 4

7 of 12

Frequency of data packets is set by

the interval command . Max = 10Hz