Install Manual

Preliminary
SKY899
Installation Manual
2-25
Rev. A
2.11 BAROMETRIC (UNCORRECTED) ALTITUDE INPUTS
The TRC requires an uncorrected barometric altimeter input. The barometric altitude can be gilham code
or ARINC-429 (air data computer (ADC)).
NOTES
1. Only one uncorrected barometric altimeter input source, either gilham code,
ARINC-429 (ADC) should be connected.
2. The uncorrected barometric altimeter input (gilham code or ARINC-429) should
be from the same source that is interfaced with the transponder or it must be at
least as accurate as that source, i.e., ± 125 ft.
2.11.1 Gilham Code (Encoding Altimeter)
These signals are gilham code inputs coming from an airdata computer or altitude digitizer (encoding
altimeter). These 11 lines may be connected in parallel with the aircraft transponder. If the aircraft is
equipped with selectable altitude encoders, connect the altitude inputs so that SKY899 is always
connected to the selected encoder. (Reference ARINC 572-1.)
NOTE
If the aircraft has switched encoders that use 28V RETURN or AIRCRAFT
GROUND as reference for encoder selection, then ALTITUDE COMMON
should be left unconnected.
Altitude encoder connections:
A1 -to- P1-56 B1 -to- P1-59 C1 -to- P1-67 D2* -to- P1-70
A2 -to- P1-57 B2 -to- P1-60 C2 -to- P1-68 D4 -to- P1-71
A4 -to- P1-58 B4 -to- P1-61 C4 -to- P1-69
ALTITUDE COMMON - to P1-72
* If D2 is not used P1-70 should remain unconnected
2.11.2 ADC (ARINC-429)
ADC (ARINC-429) speed can be 12.5 or 100 kHz and must be paired with another input device set to the
same speed. Refer to paragraph 2.9 for ARINC-429 receiver channel information.
2.12 GPS (ARINC-429)
The GPS (ARINC-429) speed can be 12.5 or 100 kHz and must be paired with another input device set to
the same speed. Refer to paragraph 2.9 for ARINC-429 receiver channel information. In order to use
ADS-B, SKYWATCH HP requires a GPS input that is GAMA or ARINC-743A compliant.
2.13 HEADING INPUT
The magnetic heading can be provided by synchro (XYZ) or ARINC-429 (attitude heading and reference
system), depending on the configuration settings. Heading source will be selected during system setup via
the service menu. Select only one heading source for the input.
2.13.1 Compass Synchro (XYZ)
Synchro (XYZ) heading input accepts ARINC 407, 407-1 signals. The FLAG line input provides the TRC
with flag status (or heading valid) information. The status of the heading valid signal can be none, active
high, or active low (see appendix A for signal characteristics) and must be selected during system setup via
the service menu.