Publication: Magyar Közlöny
Issue: MK-2007-70 (Year: 2007, Number: 70)
Era: 2004-2010
Section: Melléklet a 2007. évi XLVI. törvényhez
Paragraph Index: 4638

b) the message is cancelled (3.1.2.10.5.4) by the data link avionics. Note.— The protocols of 3.1.2.7.7.1 will then result in the delivery of the message to the reserved site. The data link avionics may cancel the message if delivery to the reserved site cannot be accomplished. 3.1.2.7.7.2 Delivery of downlink ELMs. The interrogator shall extract a downlink ELM by transmitting a Comm- C interrogation with RC equals 3. This interrogation shall carry the SRS subfield which specifies the segments to be transmitted. On receipt of this request, the transponder shall transfer the requested segments by means of Comm-D replies with KE equals 0 and ND corresponding to the number of the segment in MD. The first segment shall be transmitted 128 microseconds plus or minus 0.25 microsecond following the sync phase reversal of the interrogation 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume IV 28/11/02 3-50 requesting delivery and subsequent segments shall be transmitted at a rate of one every 136 microseconds plus or minus 1 microsecond. If a request is received to transmit downlink ELM segments and no message is waiting, each reply segment shall contain all ZEROs in the MD field. Note 1.— The requested segments may be transmitted in any order. Note 2.— Segments lost in downlink transmissions will be requested again by the interrogator on a subsequent interrogation carrying the SRS subfield. This process is repeated until all segments have been transferred. 3.1.2.7.7.2.1 SRS, segment request subfield in MC. This 16-bit (9-24) uplink subfield in MC shall request the transponder to transfer downlink ELM segments. Starting with bit 9, which denotes segment number 0, each of the following bits shall be set to ONE if the transmission of the corresponding segment is requested. SRS shall appear in MC if RC equals 3 in the same interrogation. 3.1.2.7.7.2.2 D-timer restart. The D-timer shall be restarted each time that a request for Comm-D segments is received if the Comm-D II is non-zero. Note.— The requirement for the Comm-D II to be non-zero prevents the D-timer from being restarted during a nonselective downlink ELM transaction. 3.1.2.7.7.3 Multisite downlink ELM closeout. The interrogator shall close out a multisite downlink ELM by transmitting either a surveillance or a Comm-A interrogation containing: The transponder shall compare the IIS of the interrogation to the Comm-D II and if the interrogator identifiers do not match, the state of the downlink process shall not be changed. If the interrogator identifiers match, and if a request for transmission has been complied with at least once, the transponder shall set the Comm-D II to 0, reset the D-timer, clear the DR code for this message and clear the message itself. If another downlink ELM is waiting to be transmitted, the transponder shall set the DR code (if no Comm-B message is waiting to be delivered) so that the reply contains the announcement of the next message. 3.1.2.7.7.4 Automatic expiration of downlink ELM reservation. If the D-timer period expires before a multisite closeout has been accomplished, the Comm-D II shall be set to 0, and the D-timer reset. The message and DR code shall not be cleared. Note.— This makes it possible for another site to read and clear this message. 3.1.2.7.8 NON-SELECTIVE DOWNLINK ELM Note.— In cases where the multisite protocols are not required (i.e. no overlapping coverage or sensor coordination via ground-to-ground communication), the non-selective downlink ELM protocol may be used. Non-selective downlink ELM delivery shall take place as described in 3.1.2.7.7.2. 3.1.2.7.8.1 Non-selective downlink ELM closeout. The interrogator shall close out a non-selective downlink ELM by transmitting PC equals 6 (downlink ELM closeout) in a surveillance or Comm-A interrogation. On receipt of this command, and if a request for transmission has been complied with at least once, the transponder shall perform closeout unless the D-timer is running. If the D-timer is running, indicating that a multisite reservation is in effect, the closeout shall be accomplished as per 3.1.2.7.7.3. either DI = 1 IIS = assigned interrogator identifier MES = 4, 5 or 7 (downlink ELM closeout) or DI = 0, 1 or 7 IIS = assigned interrogator identifier PC = 6 (downlink ELM closeout). 2007/70/II. szám Chapter 3 Annex 10 — Aeronautical Telecommunications 3-51 28/11/02 3.1.2.7.9 ENHANCED DOWNLINK ELM PROTOCOL Note.— The enhanced downlink ELM protocol provides a higher data link capacity by permitting parallel delivery of downlink ELM messages by up to sixteen interrogators, one for each II code. Operation without the need for multisite downlink ELM reservations is possible in regions of overlapping coverage for interrogators equipped for the enhanced downlink ELM protocol. The protocol is fully conformant to the standard multisite protocol and thus is compatible with interrogators that are not equipped for the enhanced protocol. 3.1.2.7.9.1 General 3.1.2.7.9.1.1 The interrogator shall determine from the data link capability report whether the transponder supports the enhanced protocols. If the enhanced protocols are supported, downlink ELMs delivered using the multisite-directed protocol may be delivered without a prior reservation. If the enhanced protocols are not supported by both the interrogator and the transponder, the multisite reservation protocols specified in 3.1.2.6.11 shall be used for multisite and multisitedirected downlink ELMs. 3.1.2.7.9.1.2 Recommendation.— If the transponder and the interrogator are equipped for the enhanced protocol, the interrogator should use the enhanced downlink protocol. 3.1.2.7.9.2 Enhanced multisite downlink ELM protocol 3.1.2.7.9.2.1 The transponder shall be capable of storing a sixteen segment message for each of the sixteen II codes. 3.1.2.7.9.2.2 Initialization. A multisite message input into the transponder shall be stored in the registers assigned to II = 0. 3.1.2.7.9.2.3 Announcement and extraction. A waiting multisite downlink ELM message shall be announced in the DR field of the replies to all interrogators for which a multisite directed downlink ELM message is not waiting. The UM field of the announcement reply shall indicate that the message is not reserved for any II code, i.e. the IIS subfield shall be set to 0. When a command to reserve this message is received from a given interrogator, the message shall be reserved for the II code contained in the interrogation from that interrogator. After readout and until closeout, the message shall continue to be assigned to that II code. Once a message is assigned to a specific II code, announcement of this message shall no longer be made in the replies to interrogators with other II codes. If the message is not closed out by the associated interrogator for the period of the D-timer, the message shall revert back to multisite status and the process shall repeat. Only one multisite downlink ELM message shall be in process at a time. 3.1.2.7.9.2.4 Closeout. A closeout for a multisite message shall only be accepted from the interrogator that was assigned most recently to transfer the message. 3.1.2.7.9.2.5 Announcement of the next message waiting. The DR field shall indicate a message waiting in the reply to an interrogation containing a downlink ELM closeout if an unassigned multisite downlink ELM is waiting, or if a multisite directed message is waiting for that II code (3.1.2.7.9.2). 3.1.2.7.9.3 Enhanced multisite directed downlink ELM protocol 3.1.2.7.9.3.1 Initialization. When a multisite directed message is input into the transponder, it shall be placed in the downlink ELM registers assigned to the II code specified for the message. If the registers for this II code are already in use (i.e. a multisite directed downlink ELM message is already in process for this II code), the new message shall be queued until the current transaction with that II code is closed out. 3.1.2.7.9.3.2 Announcement. Announcement of a downlink ELM message waiting transfer shall be made using the DR field as specified in 3.1.2.7.7.1 with the destination interrogator II code contained in the IIS subfield as specified in 3.1.2.6.5.3.2. The DR field and IIS subfield contents shall be set specifically for the interrogator that is to receive the reply. A waiting multisite directed message shall only be announced in the replies to the intended interrogator. It shall not be announced in replies to other interrogators. 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume IV 28/11/02 3-52 3.1.2.7.9.3.3 Delivery. An interrogator shall determine if it is the reserved site through coding in the UM field and, if so, it may proceed to request delivery of the downlink ELM. The delivery shall be performed as specified in 3.1.2.7.7.2. The transponder shall transmit the message contained in the buffer associated with the II code specified in the IIS subfield of the segment request interrogation. 3.1.2.7.9.3.4 Closeout. Closeout shall be accomplished as specified in 3.1.2.7.7.3 except that a message closeout shall only be accepted from the interrogator with a II code equal to the one that transferred the message. 3.1.2.7.9.3.5 Announcement of the next message waiting. The DR field shall indicate a message waiting in the reply to an interrogation containing a downlink ELM closeout if another multisite directed message is waiting for that II code, or if a downlink message is waiting that has not been assigned a II code (3.1.2.7.9.2). 3.1.2.7.9.4 Enhanced non-selective downlink ELM protocol. The availability of a non-selective downlink ELM message shall be announced to all interrogators. Otherwise, the protocol shall be as specified in 3.1.2.7.7. 3.1.2.8 AIR-AIR SERVICE AND SQUITTER TRANSACTIONS Note.— Airborne collision avoidance system (ACAS) equipment uses the formats UF or DF equals 0 or 16 for air-air surveillance. 3.1.2.8.1 SHORT AIR-AIR SURVEILLANCE, UPLINK FORMAT 0 The format of this interrogation shall consist of these fields: 3.1.2.8.1.1 AQ: Acquisition. This 1-bit (14) uplink field shall contain a code which controls the content of the RI field. 3.1.2.8.1.2 RL: Reply length. This 1-bit (9) uplink field shall command the format to be used for the reply. Note.— A transponder associated with airborne collision avoidance equipment would reply with DF equals 16 in response to an interrogation with RL equals 1. 3.1.2.8.1.3 DS: Data selector. This 8-bit (15-22) uplink field shall contain the BDS code (3.1.2.6.11.2.1) of the GICB register whose contents shall be returned to the corresponding reply with DF equals 16. UF RL AQ DS AP Field Reference UF uplink format 3.1.2.3.2.1.1 spare — 3 bits RL reply length 3.1.2.8.1.2 spare — 4 bits AQ acquisition 3.1.2.8.1.1 DS data selector 3.1.2.8.1.3 spare — 10 bits AP address/parity 3.1.2.3.2.1.3 Coding signifies a reply with DF = 0 signifies no reply 2007/70/II. szám Chapter 3 Annex 10 — Aeronautical Telecommunications 3-53 28/11/02 3.1.2.8.2 SHORT AIR-AIR SURVEILLANCE, DOWNLINK FORMAT 0 This reply shall be sent in response to an interrogation with UF equals 0 and RL equals 0. The format of this reply shall consist of these fields: 3.1.2.8.2.1 VS: Vertical status: This 1-bit (6) downlink field shall indicate the status of the aircraft (3.1.2.6.10.1.2). 3.1.2.8.2.2 RI: Reply information, air-air. This 4-bit (14-17) downlink field shall report the aircraft’s maximum cruising true airspeed capability and type of reply to interrogating aircraft. The coding shall be as follows: Note.— “.LE.” means “less than or equal to” and “.GT.” means “greater than”. 3.1.2.8.2.3 CC: Cross-link capability. This 1-bit (7) downlink field shall indicate the ability of the transponder to support the cross-link capability, i.e. decode the contents of the DS field in an interrogation with UF equals 0 and respond with the contents of the specified GICB register in the corresponding reply with DF equals 16. DF VS CC RI AC AP Field Reference DF downlink format 3.1.2.3.2.1.2 VS vertical status 3.1.2.8.2.1 CC cross-link capability 3.1.2.8.2.3 spare — 6 bits RI reply information 3.1.2.8.2.2 spare — 2 bits AC altitude code 3.1.2.6.5.4 AP address/parity 3.1.2.3.2.1.3 Coding signifies that the aircraft is airborne signifies that the aircraft is on the ground signifies a reply to an air-air interrogation UF = 0 with AQ = 0, no operating ACAS 1-7 reserved for ACAS 8-15 signifies a reply to an air-air interrogation UF = 0 with AQ = 1 and that the maximum airspeed is as follows: no maximum airspeed data available maximum airspeed is .LE. 140 km/h (75 kt) maximum airspeed is .GT. 140 and .LE. 280 km/h (75 and 150 kt) maximum airspeed is .GT. 280 and .LE. 560 km/h (150 and 300 kt) maximum airspeed is .GT. 560 and .LE. 1 110 km/h (300 and 600 kt) maximum airspeed is .GT. 1 110 and .LE. 2 220 km/h (600 and 1 200 kt) maximum airspeed is more than 2 220 km/h (1 200 kt) not assigned. Coding signifies that the transponder cannot support the cross-link capability signifies that the transponder supports the cross-link capability. 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume IV 28/11/02 3-54 3.1.2.8.3 LONG AIR-AIR SURVEILLANCE, DOWNLINK FORMAT 16 This reply shall be sent in response to an interrogation with UF equals 0 and RL equals 1. The format of this reply shall consist of these fields: 3.1.2.8.3.1 MV: Message, ACAS. This 56-bit (33-88) downlink field shall contain GICB information as requested in the DS field of the UF 0 interrogation that elicited the reply. Note.— The MV field is also used by ACAS for air-air coordination (4.3.8.4.2.4). 3.1.2.8.4 AIR-AIR TRANSACTION PROTOCOL Note.— Interrogation-reply coordination for the air-air formats follows the protocol outlined in Table 3-5 (3.1.2.4.1.3.2.2). The most significant bit (bit 14) of the RI field of an air-air reply shall replicate the value of the AQ field (bit 14) received in an interrogation with UF equals 0. If AQ equals 0 in the interrogation, the RI field of the reply shall contain the value 0. If AQ equals 1 in the interrogation, the RI field of the reply shall contain the maximum cruising true airspeed capability of the aircraft as defined in 3.1.2.8.2.2. In response to a UF = 0 with RL = 1 and DS ≠ 0, the transponder shall reply with a DF = 16 reply in which the MV field shall contain the contents of the GICB register designated by the DS value. In response to a UF = 0 with RL = 1 and DS = 0, the transponder shall reply with a DF = 16 with an MV field of all zeros. Receipt of a UF = 0 with DS ≠0 but RL = 0 shall have no associated ACAS cross-link action, and the transponder shall reply as specified in 3.1.2.8.2.2. 3.1.2.8.5 ACQUISITION SQUITTER Note.— SSR Mode S transponders transmit acquisition squitters (unsolicited downlink transmissions) to permit passive acquisition by interrogators with broad antenna beams, where active acquisition may be hindered by all-call synchronous garble. Examples of such interrogators are an airborne collision avoidance system and an airport surface surveillance system. 3.1.2.8.5.1 Acquisition squitter format. The format used for acquisition squitter transmissions shall be the all-call reply, (DF = 11) with II = 0. 3.1.2.8.5.2 Acquisition squitter rate. Acquisition squitter transmissions shall be emitted at random intervals that are uniformly distributed over the range from 0.8 to 1.2 seconds using a time quantization of no greater than 15 milliseconds relative to the previous acquisition squitter, with the following exceptions: DF VS RI AC MV AP Field Reference DF downlink format 3.1.2.3.2.1.2 VS vertical status 3.1.2.8.2.1 spare — 7 bits RI reply information 3.1.2.8.2.2 spare — 2 bits AC altitude code 3.1.2.6.5.4 MV message, ACAS 3.1.2.8.3.1 AP address/parity 3.1.2.3.2.1.3 2007/70/II. szám Chapter 3 Annex 10 — Aeronautical Telecommunications 3-55 28/11/02

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