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henryhallam/GPS LNAV message excerpt 2016-07-19

Created July 19, 2016 19:25
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GPS LNAV message excerpt 2016-07-19
Words 6 through 10 from Subframe 4, Page 18 of five satellites shortly after 2016-07-19T19:00:00:00Z
See IS-GPS-200H pp. 83, 116-118, 124-125
GPS L1CA 19 SF4 P18 W6-10 = 3FFFFFAF 0000003F 0018DC9E 046241F1 04800010
6 LSB parity bits included (already checked), so right-shift each word
by 6 before extracting hex field values
Field Hex Decimal Scale
A1 FFFFFE -2 *2^-30
A0 00000000 0 *2^-50
tot 63 99 *2^12
WNt 72 114
dtLS 11 17
WNLSF 89 137
DN 07 7
dtLSF 12 18
GPS L1CA 6 SF4 P18 W6-10 = 3FFFFFAF 0000003F 00139CA2 044EC0EB 044000D8
GPS L1CA 12 SF4 P18 W6-10 = 3FFFFFAF 0000003F 0018DC9E 046241F1 04800010
GPS L1CA 15 SF4 P18 W6-10 = 3FFFFD4F 3FFFFFFC 3F58DC8D 046241CE 0480007C
GPS L1CA 13 SF4 P18 W6-10 = 3FFFFFAF 0000003F 0018DC9E 046241F1 04800010
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Couple more:

GPS L1CA 24 SF4 P18 W6-10 = 3FFFFD4F 3FFFFFFC 3F58DC8D 046241CE 0480007C
GPS L1CA  2 SF4 P18 W6-10 = 3FFFFD4F 3FFFFFFC 3F58DC8D 046241CE 0480007C

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