Install Manual Part 3

SKY497
Installation Manual
A-1
Rev. C
APPENDIX A
SKY497 INTERFACE
SIGNAL & CABLE CHARACTERISTICS
A.1 INTRODUCTION
This appendix defines the electrical characteristics of all input and output signals to the SKY497 System.
Sufficient data is included to perform an electrical load analysis for the aircraft. The interface
characteristics contained in this appendix are fully compatible with ARINC specifications where noted.
Connection information identifies the connector-pin and signal names as they appear on the interconnect
wiring diagram(figures 2-2 and 2-3) or, in the case of antenna cables, the connector type (e.g., BNC or
TNC).
NOTE
External isolation diodes are not required and SHOULD NOT be installed.
SIGNAL CHARACTERISTICS
Altitude Digitizer / These signals are Gilham Code (or Gray Code) inputs coming from an
Encoding Altimeter Input airdata computer or altitude digitizer (see para 2.6.6). These 10 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 SKY497 is always connected to the selected encoder. (Reference
ARINC 572-1.)
NOTE
Only one altimeter input source (Gray Code or ARINC 429, not both)
should be connected. The altimeter input should be from the same source
that is interfaced with the transponder or at least as accurate as that
source, i.e., ± 125 ft.
CONNECTION TRC P1-40 (ALT_A1)
TRC P1-41 (ALT_A2)
TRC P1-50 (ALT_A4)
TRC P1-51 (ALT_B1)
TRC P1-56 (ALT_B2)
TRC P1-57 (ALT_B4)
TRC P1-58 (ALT_C1)
TRC P1-59 (ALT_C2)
TRC P1-71(ALT_C4)
TRC P1-72 (ALT_D4)
TRC P1-81 (ALT_COMN)
CABLE Minimum 22 AWG wire for each connection
for lengths up to 30 ft.
VOLTAGE +30 V input max.
CURRENT <1 mA sourced per line.
FREQUENCY <100 Hz
SOURCE Z >10 kΩ per line.
MAX CAPACITANCE <20 pF per line.
NOTE
If the aircraft has switched encoders that use 28V RETURN or AIRCRAFT
GROUND as reference for encoder selection, then ALT_COMMON (TRC
P1-81) should be left unconnected.