Technical Provisions for Mode S Services and Extended Squitter

More documents

Recommendations

Info

A-38 Technical Provisions for Mode S Services and Extended Squitter between solutions is less, and varies according to the cosine of latitude. For example at 87 degrees latitude, the minimum distance between solutions is 280 NM. This is sufficiently large to provide assurance that the correct aircraft location will always be obtained. Currently no airports exist within 3 degrees of either pole, so the decoding as specified here will yield the correct location of the transmitting aircraft for all existing airports. h) A reasonableness test is applied to the resulting decoded position in accordance with §A.2.7.2. A.2.6.9.1 OVERVIEW DRAFT - Working Paper ASP TSGWP11-01 for review by the TSG during the meeting in June 2011 in Paris A.2.6.9 CPR DECODING OF RECEIVED POSITION MESSAGES The techniques described in the preceding paragraphs (locally and globally unambiguous decoding) shall be used together to decode the latitude/longitude contained in airborne, surface, intent and TIS-B position messages. The process shall begin with globally unambiguous decoding based upon the receipt of an even and an odd encoded position squitter. Once the globally unambiguous position is determined, emitter centered decoding shall be used to support subsequent decoding based upon a single position report, either even or odd encoding. A.2.6.9.2 EMITTER CENTERED LOCAL DECODING In this approach, the most recent position of the emitter shall be used as the basis for the local decoding. Note.— This produces an unambiguous decoding at each update since the transmitting aircraft cannot move more than 180 NM between position updates. A.2.7 REASONABLENESS TEST FOR CPR DECODING OF RECEIVED POSITION MESSAGES A.2.7.1 OVERVIEW Draft Note.— Although receptions of position messages will normally lead to a successful target position determination, it is necessary to safeguard against position messages that would be used to initiate or update a track with an erroneous position. A reasonableness test applied to the computed position resulting from receipt of a position message can be used to discard erroneous position updates. Since an erroneous globally unambiguous CPR decode could potentially exist for the life of a track, a reasonableness test and validation of the position protects against such occurrences. A.2.7.2 REASONABLENESS TEST APPLIED TO POSITIONS DETERMINED FROM GLOBALLY UNAMBIGUOUS DECODING A reasonableness test shall be applied to a position computed using the globally unambiguous CPR decoding per §A.2.6.7 for airborne participants or per §A.2.6.8 for surface participants. Upon receipt of the even or odd encoded position message that completes the globally unambiguous CPR decode, the receiver shall perform a reasonableness test on the position decode by the following: If the receiver position is known, calculate the distance between the decoded position and the receiver position and verify that the distance is less than the maximum operating range. If the validation fails, the receiver shall discard the decoded position, the even and odd position messages used to perform the globally unambiguous CPR decode, and reinitiate the globally unambiguous CPR decode process. 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-39 A further validation of the globally unambiguous CPR decode, passing the above test, shall be performed by the computation of a second globally unambiguous CPR decode based on reception of a new odd and an even position message as per §A.2.6.7 for an airborne participant or per §A.2.6.8 for a surface participant, both received subsequent to the respective odd and even position message used in the globally unambiguous CPR decode under validation. Upon accomplishing the additional globally unambiguous CPR decode, this decoded position and the position from the locally unambiguous CPR decode resulting from the most recently received position message shall be checked to be identical to within 5 m for an airborne decode and 1.25 m for a surface decode. If the two positions are not identical to within this tolerance, the validation is failed and the initial globally unambiguous CPR decode under validation shall be discarded and the track shall be reinitialized. Note.— The position obtained from the initial global CPR decode is subsequently updated using local CPR decoding, until an independent odd and even message pair has been received. When this occurs a second global CPR decode is performed. The resulting position is compared to the position update obtained from the local CPR decode using the most recently received message. These two positions should agree since they are computed from the same message. A.2.7.3 REASONABLENESS TEST APPLIED TO POSITIONS DETERMINED FROM LOCALLY UNAMBIGUOUS DECODING A reasonableness test shall be performed to verify that the new position does not represent an unreasonable offset from the previous aircraft position. If an unreasonable offset is detected, the local decode shall not be used to update the track. Note 1.— An unreasonable offset can result from an undetected error in the received position message. Note 2.— Although the 24-bit aircraft address for every aircraft is required to be unique, if situations arise where multiple aircraft within range of a receiver are transmitting the same 24-bit aircraft address, loss of detection of aircraft can result from performing the above reasonableness test. To safeguard against this, the position data that failed the reasonableness test can be used to support detection and reporting of a duplicate address track. Since data transmitted from aircraft with duplicate addresses can not always be easily and reliably distinguished, receivers that support detection and tracking of duplicate addresses are expected to appropriately identify these as duplicate address reports. Draft DRAFT - Working Paper ASP TSGWP11-01 for review by the TSG during the meeting in June 2011 in Paris
Page 1 and 2:
DRAFT - Working Paper ASP TSGWP11-0
Page 3 and 4:
Page 5 and 6:
Page 7 and 8:
Page 9 and 10:
Page 11 and 12: 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 61: 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 113 and 114:
Appendix A A-89 MB FIELD DRAFT - Wo
Page 115 and 116:
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?