Technical Provisions for Mode S Services and Extended Squitter

DRAFT - Working Paper ASP TSGWP11-01 for review by the TSG during the meeting in June 2011 in Paris
C-40 Technical Provisions for Mode S Services and Extended Squitter
C.2.4 INITIALIZATION AND TIMEOUT
Note.— Initialization and timeout functions for Extended Squitter broadcast are performed by the
transponder and are specified in RTCA/DO-181D (EUROCAE ED-73C). A description of these functions is
presented in the following paragraphs to serve as reference material for the section on the GFM (§C.2.5).
C.2.4.1 INITIATION OF EXTENDED SQUITTER BROADCAST
At power up initialization, the transponder shall commence operation in a mode in which it broadcasts only
acquisition squitters. The transponder shall initiate the broadcast of Extended Squitters for Airborne
Position, Surface Position, Aircraft Identification and Category, Airborne Velocity, Target State and Status
and Operational Status when data are inserted into Registers 0516, 0616, 0816, 0916, 6216 and 6516 respectively. This determination shall be made individually for each squitter type. The insertion of just
altitude or surveillance status data into Register 0516 by the transponder shall not satisfy the minimum
requirement for broadcast of the airborne position squitter.
Note.— This suppresses the transmission of Extended Squitters from aircraft that are unable to report
position, velocity or identity information.
C.2.4.2 EXTENDED SQUITTER BROADCAST RATES
The maximum 1090 MHz ADS-B message transmission rate shall not exceed 6.2 transmitted messages per
second, averaged over any 60 second interval (see §3.1.2.8.9.1, Annex 10, Vol. IV).
Note.— Transponders are limited to no more than 2 Event Driven messages per second. Therefore, the
average of 2 Airborne Position, 2 Airborne Velocity, 0.2 Identification, and 2 Periodic Status and Event
Driven messages per second, averaged over any 60 second interval, yields the required 6.2 messages per
second.
The summary of all extended squitter broadcast rates is presented in Table C-35.
Table C-35. 1090 MHz Extended Squitter ADS-B Message Broadcast Rates
Transponder
Register
Event Driven
Message
Priority
1090ES ADS-B Message
On-the-Ground,
not moving
Broadcast Rate
On-the-Ground
and moving
Airborne
BDS 0,5 N/A Airborne Position N/A N/A
2 / 1 second
(0.4 – 0.6 sec)
LOW RATE
HIGH RATE
BDS 0,6 N/A Surface Position
1 / 5 seconds
2 / 1 second
N/A
(4.8 – 5.2 sec)
(0.4 – 0.6 sec)
LOW RATE
HIGH RATE
HIGH RATE
BDS 0,8 N/A Aircraft Identification and Category 1 / 10 seconds
1 / 5 seconds
1 / 5 seconds
(9.8 – 10.2 sec)
(4.8 – 5.2 sec)
(4.8 – 5.2 sec)
BDS 0,9 N/A Airborne Velocity N/A N/A
TCAS RA or Mode A Code Change
2 / 1 second
(0.4 – 0.6 sec)
BDS 6,1
TCAS RA = 1
Emergency = 2
Aircraft Status
(Emergency/Priority Status, Subtype=1)
(TCAS RA Broadcast, Subtype=2)
0.7 – 0.9 seconds
No TCAS RA, No Mode A Change
4.8 – 5.2 seconds
No TCAS RA, No Mode A Change, No Emergency, Mode A Code set to 10008 No Transmission
BDS 6,2 N/A Target State and Status (TSS) N/A N/A 1.2 – 1.3 seconds
No change NICSUPP/NAC/SIL 2.4 – 2.6 seconds
TSS being broadcast or not
No change TCAS/NAC/SIL/NICSUPP 2.4 – 2.6 seconds
TSS being broadcast
BDS 6,5 N/A Aircraft Operational Status 4.8 – 5.2 seconds
Change in NICSUPP/NAC/SIL 0.7 – 0.9 seconds
Change in TCAS/NAC/SIL/NICSUPP 2.4 – 2.6 seconds
TSS not broadcast 2
Change in TCAS/NAC/SIL/NICSUPP 0.7 – 0.9 seconds
N/A = Not Applicable
Draft
DRAFT - Working Paper ASP TSGWP11-01 for review by the TSG during the meeting in June 2011 in Paris