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Technical Provisions for Mode S Services and Extended Squitter

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DRAFT - Working Paper ASP TSGWP11-01 <strong>for</strong> review by the TSG during the meeting in June 2011 in Paris<br />

Appendix A A-95<br />

A.3.2.2.3.3 After duplicate elimination, the TIS traffic data <strong>for</strong> a given grouping shall always begin with a “first” segment<br />

message. This message shall contain the own-heading value <strong>for</strong> the group. Additional TIS traffic data messages in the<br />

grouping (if present) shall be structured as indicated in the table below:<br />

Number of traffic aircraft Structure of group<br />

1 First<br />

2 First<br />

3 First <strong>and</strong> final<br />

4 First <strong>and</strong> final<br />

5 First, 1 intermediate, <strong>and</strong> final<br />

6 First, 1 intermediate, <strong>and</strong> final<br />

7 First, 2 intermediates, <strong>and</strong> final<br />

8 First, 2 intermediates, <strong>and</strong> final<br />

etc. First, intermediates, <strong>and</strong> final<br />

A.3.2.2.3.4 The receipt of a “first” segment shall start the <strong>for</strong>mation of a message group. Subsequent TIS traffic data<br />

uplink messages shall be added to the group until one of the following conditions occurs:<br />

a) a TIS uplink of type “final” is received (the final is part of the group);<br />

b) a TIS uplink of type “first” segment, “keep-alive”, or “goodbye” is received; or<br />

c) more than 6 seconds have elapsed since the start of the group.<br />

A.3.2.2.3.5 All the traffic blocks in the TIS traffic data message group (1 to n) shall <strong>for</strong>m the display <strong>for</strong> the current time.<br />

A new group shall then be initiated by the receipt of another TIS traffic data uplink “first” segment message. TIS traffic<br />

data uplink messages of type “intermediate” or “final” shall be ignored if a new group has not been initiated by receipt of<br />

a “first” segment.<br />

A.3.2.2.4 TIS ESTABLISHMENT/DISCONNECTION PROTOCOLS<br />

Draft<br />

The processing required to establish/disconnect TIS with <strong>Mode</strong> S ground interrogators when coverage boundaries are<br />

crossed shall be based upon in<strong>for</strong>mation contained in the capability registers within the aircraft’s <strong>Mode</strong> S transponder as<br />

well as two specific TIS uplink messages.<br />

A.3.2.2.4.1 <strong>Mode</strong> S capability report<br />

Transponder register 1016 within the <strong>Mode</strong> S transponder shall contain bits that indicate the capability level of the aircraft<br />

with respect to <strong>Mode</strong> S functions. This register shall be read by each <strong>Mode</strong> S ground interrogator that acquires the<br />

aircraft. Bit 25 of this register shall be set to “ONE” if the aircraft carries any MSP data link services (i.e. TIS).<br />

Note.— This bit merely indicates the presence of MSP data link services on board the aircraft — it does NOT<br />

indicate whether any of these services are in use by the aircrew at a given time.<br />

A.3.2.2.4.2 MSP capability report<br />

Transponder registers 1D16 to 1F16 within the <strong>Mode</strong> S transponder contain bits which indicate the dynamic state of<br />

certain MSP data services on board the aircraft (where defined in applications, e.g. TIS). These registers shall be read<br />

DRAFT - Working Paper ASP TSGWP11-01 <strong>for</strong> review by the TSG during the meeting in June 2011 in Paris

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