AXP340 Transponder Installation Manual
10 March 2014
01201-00
Issue AF
AVIDYNE CORPORATION
Page 21
Enter the 6 digit aircraft address using the numeric buttons or selector knob and confirm selection by
pressing the selector knob.
For N registered aircraft, this address may be pre-populated based on the registration number.
Press FUNC to move to the next menu item.
6.1.3
VFR Squawk Code
When the pilot presses the VFR button, a pre-programmed code will replace the current squawk code. The
code is set up next; the choice of code will depend on the normal location of the aircraft. In the USA, the
VFR squawk code is 1200. In most parts of Europe, the VFR squawk code should be set to 7000.
Enter the 4 digit squawk code using the numeric buttons.
Press selector knob to move to the next menu item.
6.1.4
Airspeed Category
Mode S transponders can transmit their maximum airspeed characteristics to aircraft equipped with TCAS.
This information is used to help identify threats and to plan avoiding action by the TCAS equipped aircraft.
The airspeeds are grouped in ranges; rotate the selector knob to choose the range that corresponds to the
aircraft. Press the selector knob to accept and move to the next menu item.
6.1.5
Aircraft Category
To assist ATC tracking of aircraft, an aircraft category can be transmitted by Mode S transponders. Using
the selector knob, choose the aircraft category that most closely matches the aircraft in which the
transponder is installed. Press selector knob to accept and move to the next menu item.
6.1.6
Squat Switch Source
The Squat switch input allows the transponder to automatically switch between Airborne and Ground
modes, and to automatically start and stop the flight timer. The sense of the squat switch input can be
selected using the selector knob. Press selector knob to accept and move to the next menu item.
If the squat switch input is not connected the “Not Connected” option must be selected.
6.1.7
GPS Input
If a GPS is connected for ADS-B position reporting, select the appropriate interface protocol using the
selector knob. Press selector knob to accept and move to the next menu item.
6.1.8
GPS Line Speed
If a GPS input has been configured, you should select the appropriate line speed using the selector knob.
Press selector knob to accept and move to the next menu item.
The Avidyne IFD440 and IFD540 use the Trig ADS-B protocol at 38400 bps. GPS receivers using the
Garmin protocol run at 9600 bps. Panel mount GPS units with Aviation format outputs generally also run at
9600 bps. NMEA GPS units generally run at 4800 bps. Freeflight 1201 and NexNav 3101 GPS receivers
generally run at 19200 bps.
6.1.9
GPS System Certification Level
An important metric for ADS-B ground system behaviour is the SDA or System Design Assurance level. It
is intended to reflect the probability that the GPS position source is providing erroneous information, and is
