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
Chapter 3
OVERVIEW OF EXTENDED SQUITTER VERSION 1
3.1 EXTENDED SQUITTER VERSION 1
3.1.1 The formats and protocols for 1090ES were revised in part to overcome the limitation of the reporting of
surveillance quality using only navigation uncertainty category (NUC). In the revised formats and protocols, surveillance
accuracy and integrity are reported separately as:
a) navigation accuracy category (NAC);
b) navigation integrity category (NIC); and
c) surveillance integrity level (SIL).
3.1.2 Other features added in Version 1 messages include the reporting of additional status parameters and
formats for traffic information service — broadcast and ADS-B rebroadcast (ADS-R).
3.1.3 Version 1 formats are fully compatible with those of Version 0, in that a receiver of either version can
correctly receive and process messages of either version. The Version 1 formats and protocols in this manual are
consistent with RTCA DO-260A [Ref 34].
3.2 TRAFFIC INFORMATION SERVICE — BROADCAST (TIS-B)
Draft
3.2.1 The principle use of TIS-B is to complement the operation of ADS-B by providing ground-to-air broadcast of
surveillance data on aircraft that are not equipped for 1090 MHz ADS-B OUT as an aid to transition to a full ADS-B
environment. The basis for this ground surveillance data may be an air traffic control (ATC) Mode S radar, a surface or
approach multilateration system or a multi-sensor data processing system. The TIS-B ground-to-air transmissions use
the same signal formats as 1090 MHz ADS-B and can therefore be accepted by a 1090 MHz ADS-B receiver.
3.2.2 TIS-B service is intended to provide a complete surveillance picture to 1090 MHz ADS-B IN users during a
transition period. After transition, it also provides a means to cope with a user that has lost 1090 MHz ADS-B capability,
or is broadcasting incorrect information.
3.3 AUTOMATIC DEPENDENT SURVEILLANCE — REBROADCAST (ADS-R)
The principle use of ADS-R is to provide interoperability in airspace where multiple different ADS-B data links are
operating. ADS-B transmissions on a data link other than 1090 MHz are received and converted to extended squitter
formats and broadcast by a ground system on the 1090 MHz ADS-B data link.
3-1
DRAFT - Working Paper ASP TSGWP11-01 for review by the TSG during the meeting in June 2011 in Paris