GH-3100
Installation & Operation Manual
Page 5-34
Operation
TP-559
March 30, 2017
Revision K
5.3.5.8.8 TACAN Digital Display Data
Display data is available for Slant Range Distance, ground speed, and time-to-go data.
5.3.5.8.9 TACAN Transceiver Operation
Multi-Channel TACAN Transceivers with ARINC 429 outputs transmit TACAN data in groups.
5.3.6 Magnetic Heading Display Data
When the unit is configured to use HEADING INPUT from a MAGNETOMETER, INTERFACE
ADAPTOR, or an ARINC 429 input. The heading data, selected course arrow and descriptor are shown
on the horizontal tape.
5.3.6.1 Heading Interface
If a magnetometer is used to provide heading information, the magnetometer must be mounted in a
magnetic interference free area and must produce output data that consists of magnetic field signals for
each of the three orthogonal axes.
5.3.6.2 Free Heading Mode
Free mode is defined as a condition whereby external sensor heading information is not available but
heading computations can continue using internal rate sensing information from the unit internal sensors.
If external heading information becomes invalid, the GH-3100 switches to operating in the “free
mode”(using internal sensors only for heading calculations). The free mode is annunciated by display of
the “DG” indicator. A Set Heading option is added to the Pilot's Menu to allow setting/correction of the
heading value.
When external heading information becomes valid (from an invalid condition), an immediate "fast slew"
is initiated followed by the return of the normal slew rate.
5.3.6.3 Selected Course Arrow
When VOR or TACAN navigation information is shown with heading, the selected course-heading arrow
shows the Selected Course.
When valid and magnetic referenced FMS, DTK, or CRS information is shown with heading, the data is
depicted on the heading tape by the selected course-heading arrow.
When the FMS, DTK, or CRS data is invalid, the Selected Course Arrow is removed from the heading
tape.
5.3.6.4 Heading Calibration
When HEADING INPUT is configured for MAGNETOMETER, the magnetometer calibration data is
stored in the Detachable Configuration module (DCM).
When HEADING INPUT is configured for INTERFACE ADAPTER or ARINC 429, no calibration is
required (calibration is a function of the Interface Adapter).
5.3.6.5 Heading Invalidities
Heading display is considered invalid when the Sensor Failure Flag is set.
5.3.6.5.1 Invalid External Heading Reference.
When configured for heading using a Magnetometer, Interface Adapter, or ARINC 429 the external
heading reference is considered invalid when data is not received for longer than 2 seconds. After the 2-
second period, the heading display is in a "Free Drift" mode, where direction is determined by the GH-
3100 internal rate sensors. The text "DG" displays above the center of the heading tape.
