User's Manual

SYSTEM DESCRIPTION AND INSTALLATION MANUAL
T
3
CAS/Part No.9005000
Table 1-26: Uplink Format Fields
Designator
Field
Description
RL
Reply Length
Commands a reply of DF=0 Short Message or
DF=16 Long Message
RR
Reply Request
Contains length and content of the reply
requested by the interrogators
SD
Special Designator
Contains control codes affecting transponder
protocol
SI
Surveillance Identifier
Defines the surveillance identifier code
Table 1-27: Downlink Format Fields
Designator
Field
Description
AA
Address Announced
Contains the aircraft address
AC
Altitude Code
Field contains the aircraft altitude
AP
Address Parity
24-bit field contains the parity overlaid on the
address
CA
Transponder Capability
Reports transponder communication capability
CC
Crosslink Capability
Indicates the transponder’s ability to support
crosslink capability
DR
Downlink Request
Requests extraction of downlink messages from
the transponder by the interrogator
FS
Flight Status
Reports flight status of the aircraft
ID
Identification
Contains the Mode A identification code reporting
the numbers as set by the pilot
MB
Message COMM-B
56-bit MB field contains messages transmitted to
the interrogator
ME
Message Extended Squitter
56-bit downlink field used to broadcast messages
MV
Message COMM-V
Contains information used in air-to-air exchanges
and is part of the long special surveillance reply
PI
Parity/Interrogator Identity
24-bit field contains the parity overlaid on the
interrogator’s identity code
RI
Reply Information
4-bit field reports airspeed capability and the type
of reply to the interrogating aircraft
SL
TCAS Sensitivity Level
This field reports the sensitivity level at which the
TCAS unit is currently operating
Pub. No. 8600200-001, Revision 004
34-45-29
1-118
04 Nov 2014
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