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Deviation Request ETSO-C145eA1#1 Airborne Navigation Sensors Using the GPS Augmented by the SBAS (ETSO-C145eA1)

Deviates from ETSO-C145eA1 to use IS-GPS-200H instead of IS-GPS-200D, for the demodulation of GPS signals and signal processing, provided that some key features of IS-GPS-200H listed in this deviation request and only these are used.

Deviates from ETSO-C145eA1 §3.1, DO-229E and ETSO-C145eA1 Appendix 4, to use IS-GPS-200H instead of IS-GPS-200D for the demodulation of GPS signals and signal processing, provided that the following features of IS-GPS-200H and only these are used:

  • Signal tracking and data demodulation limited to GPS L1C/A signals from GPS PRN 1 to 32 and to Legacy NAV (LNAV) of Block II, Block IIA, Block IIR, Block IIR-M, Block IIF and GPS III satellites.
  • Data demodulation restricted to Legacy NAV (LNAV) data defined in IS-GPS-200H appendix II and to the use of the following bit fields and associated requirements:
    • Default navigation pattern
    • Null navigation pattern
    • bit 25 to 30 of all GPS words: parity
    • bit 1 to 8 of all GPS subframes: preamble
    • bit 23 of all GPS sub frames: Integrity Status Flag (optional provided Note 1 is fulfilled)
    • bit 31 to 48 of all GPS subframes: time of week, alert flag
    • bit 50 to 52 of all GPS subframe: subframe ID
    • bit 61 to 70 of GPS Subframe 1: week number
    • bit 73 to 84 of GPS Subframe 1: URA, Health, IODC MSB
    • bit 197 to 204 of GPS Subframe 1: TGD
    • bit 211 to 234 of GPS Subframe 1: IODC LSB, TOC
    • bit 241 to 264 of GPS Subframe 1: Ephem Af2, Af1
    • bit 271 to 292 of GPS Subframe 1: Ephem Af0
    • bit 61 to 84 of GPS Subframe 2: IODE, Ephem CRS
    • bit 91 to 114 of GPS Subframe 2: Ephem DeltaN, Ephem M0 MSB
    • bit 121 to 144 of GPS Subframe 2: Ephem M0 LSB
    • bit 151 to 174 of GPS Subframe 2: Ephem CUC, Ephem e MSB
    • bit 181 to 204 of GPS Subframe 2: Ephem e LSB
    • bit 211 to 234 of GPS Subframe 2: Ephem CUS, Ephem SqrtA MSB
    • bit 241 to 264 of GPS Subframe 2: Ephem SqrtA LSB
    • bit 271 to 287 of GPS Subframe 2: Ephem TOE, Ephem Fit interval flag
    • bit 61 to 84 of GPS Subframe 3: Ephem CIC, Ephem Omega0 MSB
    • bit 91 to 114 of GPS Subframe 3: Ephem Omega0 LSB
    • bit 121 to 144 of GPS Subframe 3: Ephem CIS, Ephem I0 MSB
    • bit 151 to 174 of GPS subframe 3: Ephem I0 LSB
    • bit 181 to 204 of GPS subframe 3: Ephem CRC, Ephem Omega MSB
    • bit 211 to 234 of GPS subframe 3: Ephem Omega LSB
    • bit 241 to 264 of GPS subframe 3: Ephem Omega dot
    • bit 271 to 292 of GPS subframe 3: Ephem IODE, Ephem Idot
    • bit 60 to 61 of GPS sub frame 4 and 5: Data ID Number
    • bit 63 to 68 of GPS subframe 4 and 5: SV ID
    • bit 69 to 84 of GPS subframe 4 and 5 with SV ID = 1 to 32: Alm e
    • bit 91 to 114 of GPS subframe 4 and 5 with SV ID = 1 to 32: Alm TOA, Alm DeltaI
    • bit 121 to 136 of GPS subframe 4 and 5 with SV ID = 1 to 32: Alm OmegaDot
    • bit 151 to 174 of GPS subframe 4 and 5 with SV ID = 1 to 32: Alm SqrtA
    • bit 181 to 204 of GPS subframe 4 and 5 with SV ID = 1 to 32: Alm Omega0
    • bit 211 to 234 of GPS subframe 4 and 5 with SV ID = 1 to 32: Alm Omega
    • bit 241 to 264 of GPS subframe 4 and 5 with SV ID = 1 to 32: Alm M0
    • bit 69 to 84 of GPS subframe 4 with SV ID = 56: Iono Alpha0, Iono Alpha1
    • bit 91 to 114 of GPS subframe 4 with SV ID = 56: Iono Alpha2, Iono Alpha3, Iono Beta0
    • bit 121 to 144 of GPS subframe 4 with SV ID = 56: Iono Beta1, Iono Beta2, Iono Beta3
    • bit 151 to 174 of GPS subframe 4 with SV ID = 56: UTC A1
    • bit 181 to 204 of GPS subframe 4 with SV ID = 56: UTC A0 MSB
    • bit 211 to 234 of GPS subframe 4 with SV ID = 56: UTC A0 LSB, UTC TOT, UTC WNT
    • bit 241 to 264 of GPS subframe 4 with SV ID = 56: UTC DTLS, UTC WNLSF, UTC DN
    • bit 271 to 278 of GPS subframe 4 with SV ID = 56: UTC DTLSF

Note 1: As the new definition in IS-GPS-200H is a superset of the definition in IS-GPS-200D, it is accepted to not decode this Integrity Status Flag bit if only the IS-GPS-200D definition is used i.e. the probability of the URE exceeding 4.42 times URA for more than 5.2 seconds, without an accompanying alert, is less than 1E-5 per hour. In this context, an "alert" is defined as any indication or characteristic of the conveying signal.