L-3 Communications SKYWATCH HP SKY899 Series, Installation Manual, Page: 135 / 184

SKY899
Installation Manual
009-11900-001 Appendix A - Page A-11
Revision F July 18, 2013
SIGNAL CHARACTERISTICS
Squat Switch Input This signal line is to be connected to the squat switch to sense when the
(Weight-On-Wheels) aircraft is on the ground (see paragraph 2.7.3). The state of the switch
can be active low or active high in reference to aircraft ground. The
switch status can be none, active low or active high, this is selected via
service menu.
If a squat switch is not installed on the aircraft, it is recommended to
install a switch, which will enhance system operation.
CONNECTION Connector-Pin Signal Name
P1-24 SQUAT
CABLE Minimum 22 AWG wire for lengths up to 30 ft.
VOLTAGE None: Open or no connection
Active Low: (ref. to aircraft electrical ground)
On Ground: -5 V dc to +2.5 V dc
Flying: +9 V dc to +32 V dc or open
Active High: (ref. to aircraft electrical ground)
On Ground: +9 V dc to +32 V dc
Flying: -5 V dc to +2.5 V dc or open
CURRENT <5 mA sourced.
Suppression Bus I/O The SKY899 outputs a 100 µs (± 5 µs) suppression pulse on the aircraft
suppression bus (see paragraph 2.21). In addition, the SKY899 receives
suppression signals from all other devices on the suppression bus (e.g.,
transponder, DME). (Reference ARINC 735-2 and DO-197A.)
CAUTION
The aircraft transponder must have suppression circuitry to
ensure that SKYWATCH
HP does not paint itself as a target
(e.g., TA).
CONNECTION Connector-Pin Signal Name
P1-93 SUPBUS
CABLE Any size low capacitance shielded cable may be
used.
VOLTAGE 18 - 70 V dc input, greater than 20 V dc output.
CURRENT 0.3 A output max.
PERIOD ATCRBS - 100 µs ± 5 µs output
SOURCE Z 2 k
Ω
LOAD Z 10.5 k
Ω
MAX CAPACITANCE <50 pF
System Configuration Module The system configuration module is used to store aircraft installation
dependent information. Aircraft specific information is selected via the
service menu, typically during system setup. Once the setup settings have
been saved the system configuration will stay with the aircraft wiring
allowing the TRC to be replaced or exchanged without having to re-
configure the TRC. When powered up the configuration information is
sent to the TRC via the bi-directional serial data bus (SDA). The
configuration module is located inside backshell of P1 connector. See
paragraph 2.22.
The document reference is online, please check the correspondence between the online documentation and the printed version.