Page 38
Doc. 13301-Tec-RevB (2022-05-25)
Technical Modes
Operating Instructions
8. Compass
The Perdix 2 contains a tilt-compensated digital
compass�
Compass Features
• 1° resolution
• ±
5° accuracy
• High-speed refresh rate
• User set heading marker with reciprocal
• True North (declination) adjustment
• Tilt compensation
±4
5°
Viewing the Compass
When enabled, the compass is viewed by pressing the
SELECT (right) button once� Press SELECT again to
continue on to view the regular info screens�
Unlike the regular info screens, the compass never
times out back to the main screen� Press MENU (left)
button to return to the main screen�
Calibration
- The digital compass needs occasional
calibration� This can be done in the
System Setup
Compass
menu� See details on page 69�
Battery Changes -
When the battery is changed, the
compass requires calibration�
Interference -
Since a compass operates by reading
the Earth’s magnetic field, the compass heading is
affected by anything that distorts that field or creates
its own� Steel objects and electric motors or cabling
(e�g� from dive lights) should be kept at a distance�
Being close to or inside a shipwreck may also affect
the compass�
Magnetic declination
(also called magnetic
variation) is the difference between magnetic
and True North� This can be compensated in the
Compass Setup menu using the True North setting�
The magnetic declination varies around the world,
so will need to be readjusted when traveling�
Magnetic inclination
(or magnetic dip) is how
much the Earth’s magnetic field points up or down�
The compass automatically compensates for this
angle� However, near the poles, the inclination
angle can exceed 80° (i�e� the magnetic field points
almost directly up or down), in which case the
specified accuracy may not be met�
Compass Limitations
Marking a Heading
To mark a heading, when viewing
the compass press the MENU
(left) button� This brings up the
“Exit/Mark” menu� Press the
SELECT (right) button to mark
the heading�
The marked heading is shown with
a green arrow� When within
±
5° of
the heading, the degrees display
turns green�
The reciprocal heading (180° from
marked heading) is shown with a
red arrow� When within
±
5° of the
reciprocal heading, the degrees
display turns red�
TIME
NE
N
24
1.30
22.1 3
DEPTH TIME STOP
When more than 5° off the
marked heading, a green arrow
shows the direction back to the
marked heading�
Also, the offset degrees to the heading are displayed
(16° in the example image)� This offset is useful when
navigating patterns� For example, a box pattern
requires turns at 90° intervals, while a triangle pattern
requires 120° turns�