Technical Provisions for Mode S Services and Extended Squitter

More documents

Recommendations

Info

A-28 Technical Provisions for Mode S Services and Extended Squitter A.2.5.5.3 EVENT-DRIVEN PRIORITY If the event-driven message transmission rate must be reduced in order not to exceed the maximum rate specified in §A.2.5.5.2, transmission priority shall be assigned as follows: 1) If the emergency/priority status message (see §A.2.3.8) is active, it shall be transmitted at the specified rate of once per second. Other active event-driven messages shall be assigned equal priority for the remaining capacity. 2) If the emergency/priority status message is not active, transmission priority shall be allocated equally to all active event-driven messages. A.2.5.6 DERIVATION OF MODE FIELD BITS FOR AIRCRAFT INTENTION PARAMETERS For aircraft architectures that do not present the GFM with a dedicated status word (containing the mode field definitions associated with aircraft intention parameters), the GFM shall derive the status from each of the appropriate FCC status words in order to set the respective bits in each of the mode fields of the register number 4016. A.2.6 LATITUDE/LONGITUDE CODING USING COMPACT POSITION REPORTING (CPR) A.2.6.1 PRINCIPLE OF THE CPR ALGORITHM The Mode S extended squitters use compact position reporting (CPR) to encode latitude and longitude efficiently into messages, as specified in §C.2.6. Notes.— DRAFT - Working Paper ASP TSGWP11-01 for review by the TSG during the meeting in June 2011 in Paris 1. The resulting messages are compact in the sense that several higher-order bits, which are normally constant for long periods of time, are not transmitted in every message. For example, in a direct binary representation of latitude, one bit would designate whether the aircraft is in the northern or southern hemisphere. This bit would remain constant for a long time, possibly the entire life of the aircraft. To repeatedly transmit this bit in every position message would be inefficient. Draft 2. Because the higher-order bits are not transmitted, it follows that multiple locations on the earth will produce the same encoded position. If only a single position message were received, the decoding would involve ambiguity as to which of the multiple solutions is the correct location of the aircraft. The CPR technique includes a provision to enable a receiving system to unambiguously determine the location of the aircraft. This is done by encoding in two ways that differ slightly. The two formats, called even-format and odd-format, are each transmitted 50 per cent of the time. Upon reception of both types within a short period (approximately 10 seconds), the receiving system can unambiguously determine the location of the aircraft. 3. Once this process has been carried out, the higher-order bits are known at the receiving station, so subsequent single message receptions serve to unambiguously indicate the location of the aircraft as it moves. 4. In certain special cases, a single reception can be decoded into the correct location without an even/odd pair. This decoding is based on the fact that the multiple locations are spaced by at least 360 NM. In addition to the correct locations, the other locations are separated by integer multiples of 360 NM to the north and south and also integer multiples of 360 NM to the east and west. In a special case in which it is known that reception is impossible beyond a range of 180 NM, the nearest solution is the correct location of the aircraft. DRAFT - Working Paper ASP TSGWP11-01 for review by the TSG during the meeting in June 2011 in Paris
DRAFT - Working Paper ASP TSGWP11-01 for review by the TSG during the meeting in June 2011 in Paris Appendix A A-29 5. The parameter values in the preceding paragraph (360 and 180 NM) apply to the airborne CPR encoding. For aircraft on the surface, the CPR parameters are smaller by a factor of 4. This encoding yields better resolution but reduces the spacing of the multiple solutions. A.2.6.2 CPR ALGORITHM PARAMETERS AND INTERNAL FUNCTIONS The CPR algorithm shall utilize the following parameters whose values are set as follows for the Mode S extended squitter application: a) The number of bits used to encode a position coordinate, Nb, is set as follows: Nb = 17 for airborne encoding used in the ADS-B airborne position message and the TIS-B fine airborne message, Nb = 19 for surface encoding used in the ADS-B surface position message and the TIS-B fine surface position message, Nb = 14 for intent encoding, Nb = 12 for TIS-B encoding, used in the TIS-B coarse airborne position message. Note 1.— The Nb parameter determines the encoded position precision (approximately 5 m for the airborne encoding, 1.25 m for the surface encoding, and 41 m for the intent encoding and 164 m for the TIS-B encoding). b) The number of geographic latitude zones between the equator and a pole, denoted NZ, is set to 15. Note 2.— The NZ parameter determines the unambiguous airborne range for decoding (360 NM). The surface latitude/longitude encoding omits the high-order 2 bits of the 19 bit CPR encoding, so the effective unambiguous range for surface position reports is 90 NM. Draft The CPR algorithm shall define internal functions to be used in the encoding and decoding processes. c) The notation floor(x) denotes the floor of x, which is defined as the greatest integer value k such that k
Page 1 and 2: DRAFT - Working Paper ASP TSGWP11-0
Page 31 and 32: Appendix A A-7 TYPE Code Format Hor
Page 37 and 38: Appendix A A-13 The supersonic vers
Page 39 and 40: Appendix A A-15 The transponder sha
Page 51: DRAFT - Working Paper ASP TSGWP11-0
Page 65 and 66: Appendix A A-41 MB FIELD DRAFT - Wo
Page 67 and 68: Appendix A A-43 MB FIELD 1 MSB TRAN
Page 71 and 72: Appendix A A-47 MB FIELD 1 2 3 4 5
Page 79 and 80: Appendix A A-55 MB FIELD 1 BDS A,8
Page 103 and 104:
Appendix A A-79 MB FIELD DRAFT - Wo
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
DRAFT - Working Paper ASP TSGWP11-0
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Appendix A A-97 a) the PI sends a T
Page 123 and 124:
Appendix A A-99 This subfield shall
Page 125 and 126:
Appendix A A-101 These channels hav
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Appendix A A-109 A.4. MODE S BROADC
Page 135 and 136:
Appendix A A-111 Note 1.— This st
Page 137 and 138:
Page 139 and 140:
Appendix B B-3 TYPE code Subtype co
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Appendix B B-17 Coding (Binary) (De
Page 155 and 156:
Appendix B B-19 a) ACAS operational
Page 157 and 158:
Appendix B B-21 Subfield Coding: DR
Page 159 and 160:
Appendix B B-23 Coding (Binary) (De
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Appendix B B-33 MB FIELD DRAFT - Wo
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Appendix B B-41 CF value ICAO/Mode
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Appendix C C-5 Table C-2. “TYPE
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Appendix C C-11 C.2.3.2.2 Time Sync
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Appendix C C-25 Notes.— DRAFT - W
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Msg Bit # “ME” Bit # Appendix C
Page 221 and 222:
Appendix C C-33 Msg Bit # "ME” Bi
Page 223 and 224:
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Appendix C C-43 Notes. — DRAFT -
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Appendix C C-51 3. The decoded posi
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
Appendix C C-57 B Reports to have k
Page 247 and 248:
Appendix C C-59 Register 0516 DRAFT
Page 249 and 250:
Page 251 and 252:
Page 253 and 254:
Appendix C C-65 Register 0A16 Figur
Page 255 and 256:
Page 257 and 258:
Page 259 and 260:
Appendix C C-71 Table C-37. CF Fiel
Page 261 and 262:
Page 263 and 264:
Page 265 and 266:
Page 267 and 268:
Page 269 and 270:
Page 271 and 272:
Page 273 and 274:
Page 275 and 276:
Page 277 and 278:
Page 279 and 280:
Page 281 and 282:
Page 283 and 284:
Page 285 and 286:
Page 287 and 288:
Appendix CD CD-3 ACTIONS EVENTS DRA
Page 289 and 290:
Page 291 and 292:
Appendix CD CD-7 too many broadcast
Page 293 and 294:
Page 295 and 296:
Page 297 and 298:
Appendix CD CD-13 CD.2.4.4.1.2 Poss
Page 299 and 300:
Appendix CD CD-15 D.2.4.4.2.1.2 A32
Page 301 and 302:
Appendix CD CD-17 AP/FD mode V/S-FP
Page 303 and 304:
Page 305 and 306:
Page 307 and 308:
Appendix CD CD-23 CD.2.4.7.5 BINARY
Page 309 and 310:
Page 311 and 312:
Appendix CD CD-27 Zone no. DRAFT -
Page 313 and 314:
Page 315 and 316:
Appendix CD CD-31 CD.4 IMPLEMENTATI
Page 317 and 318:
Page 319 and 320:
Page 321 and 322:
Page 323 and 324:
Page 325 and 326:
Appendix DE DE-7 c. for GNSS, the p
Page 327 and 328:
Appendix DE DE-9 MB FIELD DRAFT - W
Page 329 and 330:
Appendix DE DE-11 MB FIELD DRAFT -
show all

Technical Provisions for Mode S Services and Extended Squitter

Create successful ePaper yourself

Delete template?

Save as template?