Sperry Marine 5016-CA, Руководство по эксплуатации, установке и обслуживанию

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Analogue Compass Repeaters 056376/A
Functional Description 1-3
The magnetic heading repeater, type 5016-CC, is preconfigured to indi-
cate magnetic compass heading only, regardless of which source is cur-
rently active.
The magnetic heading repeater is equipped with a removable cover, hid-
ing the compass card when navigating the vessel under normal use, as
the magnetic heading repeater is only classified for the indication of
magnetic heading data in case of emergency when the gyrocompass(es)
as primary heading source(s) are not available and the vessel is actually
steered by magnetic compass heading.
1.3 Functional Description
The compass card assembly is driven through a gear train by a stepper
motor. To ensure smooth and silent operation, the microprocessorized
motor control uses micro stepping. Photo interrupters detect when the
compass cards pass their zero positions at 360° and every 10°, respec-
tively, allowing minor step losses to be automatically corrected during
operation.
Once valid heading data is received, the heading to be indicated is trans-
lated into a counter value representing the required compass cards’ off-
set from the North (zero) position. A second counter is maintained for
the cards’ current offset.
The motor control constantly executes a routine to minimize the differ-
ence between these two offsets, thus making the compass cards follow-
up to the heading to be indicated.
The position of the cards is held in non-volatile memory, so that it is not
normally required to zero (re-synchronize) the cards upon power-up.