Publication: Magyar Közlöny
Issue: MK-2009-104 (Year: 2009, Number: 104)
Era: 2004-2010
Section: 
Paragraph Index: 2268

d) air-air surveillance replies (DF = 0 and 16). 3.1.2.4.1.3.2.2.1 Replies to SSR Mode S-only all-call interrogations. The downlink format of the reply to a Mode S-only all-call interrogation (if required) shall be DF = 11. The reply content and rules for determining the requirement to reply shall be as defined in 3.1.2.5. Note.— A Mode S reply may or may not be transmitted when a Mode S interrogation with UF = 11 has been accepted. 3.1.2.4.1.3.2.2.2 Replies to surveillance and standard length communications interrogations. A Mode S reply shall be transmitted when a Mode S interrogation with UF = 4, 5, 20 or 21 and an aircraft address has been accepted. The contents of these interrogations and replies shall be as defined in 3.1.2.6. Note.— If a Mode S interrogation with UF = 20 or 21 and a broadcast address is accepted, no reply is transmitted (3.1.2.4.1.2.3.1.3). 3.1.2.4.1.3.2.2.3 Replies to extended length communications interrogations. A series of Mode S replies ranging in number from 0 to 16 shall be transmitted when a Mode S interrogation with UF = 24 has been accepted. The downlink format of the reply (if any) shall be DF = 24. Protocols defining the number and content of the replies shall be as defined in 3.1.2.7. 3.1.2.4.1.3.2.2.4 Replies to air-air surveillance interrogations. A Mode S reply shall be transmitted when a Mode S interrogation with UF = 0 and an aircraft address has been accepted. The contents of these interrogations and replies shall be as defined in 3.1.2.8. 3.1.2.4.2 SUPPRESSION 3.1.2.4.2.1 Effects of suppression. A transponder in suppression (3.1.1.7.4) shall not recognize Mode A, Mode C or intermode interrogations if either the P1 pulse alone or both the P1 and P3 pulses of the interrogation are received during the suppression interval. Suppression shall not affect the recognition of, acceptance of, or replies to Mode S interrogations. 3.1.2.4.2.2 Suppression pairs. The two-pulse Mode A/C suppression pair defined in 3.1.1.7.4.1 shall initiate suppression in a Mode S transponder regardless of the position of the pulse pair in a group of pulses, provided the transponder is not already suppressed or in a transaction cycle. Note.— The P3 – P4 pair of the Mode A/C-only all-call interrogation both prevents a reply and initiates suppression. Likewise, the P1 – P2 preamble of a Mode S interrogation initiates suppression independently of the waveform that follows it. 3.1.2.5 INTERMODE AND MODE S ALL-CALL TRANSACTIONS 3.1.2.5.1 INTERMODE TRANSACTIONS Note.— Intermode transactions permit the surveillance of Mode A/C-only aircraft and the acquisition of Mode S aircraft. The Mode A/C/S all-call interrogation allows Mode A/C-only and Mode S transponders to be interrogated by the same Annex 10 — Aeronautical Telecommunications Volume IV 22/11/07 3-18 transmissions. The Mode A/C-only all-call interrogation makes it possible to elicit replies only from Mode A/C transponders. In multisite scenarios, the interrogator must transmit its identifier code in the Mode S only all-call interrogation. Thus, a pair of Mode S-only and Mode A/C-only all-call interrogations are used. The intermode interrogations are defined in 3.1.2.1.5.1 and the corresponding interrogation-reply protocols are defined in 3.1.2.4. 3.1.2.5.2 MODE S-ONLY ALL-CALL TRANSACTIONS Note.— These transactions allow the ground to acquire Mode S aircraft by use of an interrogation addressed to all Mode S-equipped aircraft. The reply is via downlink format 11 which returns the aircraft address. The interrogation-reply protocols are defined in 3.1.2.4. 3.1.2.5.2.1 Mode S-only all-call interrogation, uplink format 11 UF PR IC CL AP The format of this interrogation shall consist of these fields: Field Reference UF uplink format 3.1.2.3.2.1.1 PR probability of reply 3.1.2.5.2.1.1 IC interrogator code 3.1.2.5.2.1.2 CL code label 3.1.2.5.2.1.3 spare — 16 bits AP address/parity 3.1.2.3.2.1.3 3.1.2.5.2.1.1 PR: Probability of reply. This 4-bit (6-9) uplink field shall contain commands to the transponder specifying the probability of reply to that interrogation (3.1.2.5.4). Codes are as follows: signifies reply with probability of 1 signifies reply with probability of 1/2 signifies reply with probability of 1/4 signifies reply with probability of 1/8 signifies reply with probability of 1/16 5, 6, 7 not assigned signifies disregard lockout, reply with probability of 1 signifies disregard lockout, reply with probability of 1/2 signifies disregard lockout, reply with probability of 1/4 signifies disregard lockout, reply with probability of 1/8 signifies disregard lockout, reply with probability of 1/16 13, 14, 15 not assigned. 3.1.2.5.2.1.2 IC: Interrogator code. This 4-bit (10-13) uplink field shall contain either the 4-bit interrogator identifier code (3.1.2.5.2.1.2.3) or the lower 4 bits of the 6-bit surveillance identifier code (3.1.2.5.2.1.2.4) depending on the value of the CL field (3.1.2.5.2.1.3). Chapter 3 Annex 10 — Aeronautical Telecommunications 3-19 22/11/07 3.1.2.5.2.1.2.1 Recommendation.— It is recommended that whenever possible an interrogator should operate using a single interrogator code. 3.1.2.5.2.1.2.2 The use of multiple interrogator codes by one interrogator. An interrogator shall not interleave Mode S-only all-call interrogations using different interrogator codes. Note.— An explanation of RF interference issues, sector size and impact on data link transactions is presented in the Manual of the Secondary Surveillance Radar (SSR) Systems (Doc 9684). 3.1.2.5.2.1.2.3 II: Interrogator identifier. This 4-bit value shall define an interrogator identifier (II) code. These II codes shall be assigned to interrogators in the range from 0 to 15. The II code value of 0 shall only be used for supplementary acquisition in conjunction with acquisition based on lockout override (3.1.2.5.2.1.4 and 3.1.2.5.2.1.5). When two II codes are assigned to one interrogator only, one II code shall be used for full data link purposes. Note.— Limited data link activity including single segment Comm-A, uplink and downlink broadcast protocols and GICB extraction may be performed by both II codes. 3.1.2.5.2.1.2.4 SI: Surveillance identifier. This 6-bit value shall define a surveillance identifier (SI) code. These SI codes shall be assigned to interrogators in the range from 1 to 63. The SI code value of 0 shall not be used. The SI codes shall be used with the multisite lockout protocols (3.1.2.6.9.1). The SI codes shall not be used with the multisite communications protocols (3.1.2.6.11.3.2, 3.1.2.7.4 or 3.1.2.7.7). 3.1.2.5.2.1.3 CL: Code label. This 3-bit (14-16) uplink field shall define the contents of the IC field. Coding (in binary) signifies that the IC field contains the II code signifies that the IC field contains SI codes 1 to 15 signifies that the IC field contains SI codes 16 to 31 signifies that the IC field contains SI codes 32 to 47 signifies that the IC field contains SI codes 48 to 63 The other values of the CL field shall not be used. 3.1.2.5.2.1.3.1 Surveillance identifier (SI) code capability report. Transponders which process the SI codes (3.1.2.5.2.1.2.4) shall report this capability by setting bit 35 to 1 in the surveillance identifier capability (SIC) subfield of the MB field of the data link capability report (3.1.2.6.10.2.2). 3.1.2.5.2.1.4 Operation based on lockout override Note 1.— The Mode S-only all-call lockout override provides the basis for acquisition of Mode S aircraft for interrogators that have not been assigned a unique IC (II or SI code) for full Mode S operation (protected acquisition by ensuring that no other interrogator on the same IC can lock out the target in the same coverage area). Note 2.— Lockout override is possible using any interrogator code. 3.1.2.5.2.1.4.1 Maximum Mode S-only all-call interrogation rate. The maximum rate of Mode S-only all-call interrogations made by an interrogator using acquisition based on lockout override shall depend on the reply probability as follows:

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