ATR833A-II / P/N 833-II (Axxx)-(Axxx)
Operation and Installation
43
Doc.-No. 01.143A.010.71e / Revision 1.00
Byte #
Value
Description
1
0x02 (STX)
Synchronization
2
0x72 (‘r’)
Synchronization
3
id
id
of message
4…3+
n
n data bytes
depending on message
4+
n
checksum
XOR of bytes #2 … #3+
n
i.e. excluding the STX and the checksum itself
Byte stuffing
If the STX byte (0x02) appears in the data byte of a message, this byte is
doubled to distinguish it from STX. The checksum then contains both
0x02 values.
The standby frequency is set with the ID 0x12 and contains two data
bytes:
Data Byte # Description
Possible Values / Remarks
1
MHz
118…136
2
kHz / 5
0…198 (corresponds to 0…990 kHz)
The standby frequency and the active frequency can also be adjusted by
Garmin devices. The protocol corresponds to the Garmin SL40.
4.7.3.3 Connector EXT-NF for Monaural Audio Input
This connector is used for the input of monaural audio signals. He can be
used e.g. for acoustic traffic warnings, for radio navigation receiver’s
acoustic identifiers, or for input of music into the headsets.
The priority of radio reception in relation to this input can be configured
as described in chapter 0.
4.8 Antenna
4.8.1 Antenna Selection
A VHF-COM-Antenna with an impedance of 50 Ohm is required.
Choose an antenna type approved for the aircraft and the mounting
location.
The antenna should be located far away from ELT-antennas and
other VHF antennas.
Specified features depend on proper installation of the antenna.
