IS-GPS-800A - US Coast Guard Navigation Center
IS-GPS-800A - US Coast Guard Navigation Center IS-GPS-800A - US Coast Guard Navigation Center
Figure 3.2-5. Parity Check Matrix H for LDPC CodeTables 6.2-2, 6.2-3, 6.2-4, 6.2-5, 6.2-6, and 6.2-7 shall define the coordinates of elements with value “1” in each of thesubmatrices A, B, C, D, E, and T, respectively, for Subframe 2. Tables 6.2-8, 6.2-9, 6.2-10, 6.2-11, 6.2-12, and 6.2-13shall define the coordinates of elements with value “1” in each of the submatrices A, B, C, D, E, and T, respectively,for Subframe 3. The inverse of T is not included in this document, however T is a lower triangular matrix andtherefore, the inverse of T can be easily identified.The rate ½ LDPC encoder shall use the given matrices A, B, T, C, D, and E of Section 6.2.4 to generate the encodedsymbols using the following algorithm:where,andtp 1 = 1 (E T 1 A + C) s ttp 2 = 1 (A s t + B p t 1 ) = E T 1 B + D,s = subframe 2 or subframe 3 data,[ ] t indicates transpose,elements of matrices p 1 and p 2 are modulo 2 numbers.The encoded symbols for broadcast are comprised of (s;p 1 ;p 2 ) where s is the systematic portion of the codeword, and{p 1, p 2} comprise the combined parity bits.22 IS-GPS-800A8 June 2010
3.2.3.5 InterleavingThe 1748 encoded symbols of subframes 2 and 3 are combined and interleaved using a block interleaver. The blockinterleaver is conceptually described using a two-dimensional array of 38 rows and 46 columns, as depicted inFigure 3.2-6. The LDPC encoded subframe 2 symbols are written first (MSB first) into the interleaver from left toright starting at Row 1. After Row 1 is filled, Row 2 is filled from left to right and this process continues until the1748 th symbol (LSB of LDPC encoded subframe 3) is written into the rightmost cell of the last (38 th ) row. Once all1748 symbols are written into the array, the symbols are sequentially read out of the array, for broadcast to user,from top to bottom starting at Column 1. After reading out the last symbol of the 38 th row in Column 1, Column 2symbols are read out from top to bottom and this process continues until the last symbol in the 38 th row of the lastcolumn (46 th ) is read out.23 IS-GPS-800A8 June 2010
- Page 1 and 2: IS-GPS-800A8 June 2010GLOBAL POSITI
- Page 3 and 4: REVISION RECORDLTR DESCRIPTION DATE
- Page 5 and 6: 3.2.3.3 Cyclic Redundancy Check ...
- Page 7 and 8: LIST OF FIGURESFigure 3.2-1. Genera
- Page 9 and 10: 1. INTRODUCTION1.1 ScopeThis Interf
- Page 11 and 12: 3. SIGNAL REQUIREMENTSThe requireme
- Page 13 and 14: Carriers of the two L1C components
- Page 15 and 16: 3.2.2 PRN Code CharacteristicsThe c
- Page 17 and 18: The overlay codes are derived from
- Page 19 and 20: 3.2-2 L1C Ranging Codes Parameter A
- Page 21 and 22: GPS PRNSignal No.3.2-3 L1C O Overla
- Page 23 and 24: FIXED LENGTH-10223 LEGENDRE SEQUENC
- Page 25 and 26: 3.2.2.2 Non-Standard CodesThe non-s
- Page 27 and 28: corresponding to MSB = 0. (A SV tra
- Page 29: This code has the following charact
- Page 33 and 34: 3.3 Signal ModulationThe signals mo
- Page 35 and 36: Bit valueL1C DbitstreamSubcarrier s
- Page 37 and 38: 3.5 Message DefinitionAs shown in F
- Page 40 and 41: DIRECTION OF DATA FLOW FROM SV100 B
- Page 42 and 43: DIRECTION OF DATA FLOW FROM SV100 B
- Page 44 and 45: DIRECTION OF DATA FLOW FROM SV100 B
- Page 46 and 47: 3.5.3 Subframe 2Subframe 2 provides
- Page 48 and 49: Table 3.5-1. Subframe 2 Parameters
- Page 50 and 51: 3.5.3.1 Transmission Week NumberBit
- Page 52 and 53: 3.5.3.6 Ephemeris Parameter Charact
- Page 54 and 55: Table 3.5-2. Elements of Coordinate
- Page 56 and 57: The user shall use the broadcast UR
- Page 58 and 59: where, ISC L1CD is provided to the
- Page 60 and 61: 3.5.3.10.1 Integrity Status Flag (I
- Page 62 and 63: The ionospheric data shall be updat
- Page 64 and 65: 3.5.4.2.3 User Algorithm for Applic
- Page 66 and 67: transmitted by the SVs will degrade
- Page 68 and 69: Table 3.5-7.Midi Almanac Parameters
- Page 70 and 71: MSBCDC = Clock Differential Correct
- Page 72 and 73: 3.5.4.5 Subframe 3, Page 6 - TextSu
- Page 74 and 75: 5. RESERVED66 IS-GPS-800A8 June 201
- Page 76 and 77: LSF - Leap Seconds FutureL1C - Comm
- Page 78 and 79: Table 6.2-1.Legendre Sequence (Octa
3.2.3.5 InterleavingThe 1748 encoded symbols of subframes 2 and 3 are combined and interleaved using a block interleaver. The blockinterleaver is conceptually described using a two-dimensional array of 38 rows and 46 columns, as depicted inFigure 3.2-6. The LDPC encoded subframe 2 symbols are written first (MSB first) into the interleaver from left toright starting at Row 1. After Row 1 is filled, Row 2 is filled from left to right and this process continues until the1748 th symbol (LSB of LDPC encoded subframe 3) is written into the rightmost cell of the last (38 th ) row. Once all1748 symbols are written into the array, the symbols are sequentially read out of the array, for broadcast to user,from top to bottom starting at Column 1. After reading out the last symbol of the 38 th row in Column 1, Column 2symbols are read out from top to bottom and this process continues until the last symbol in the 38 th row of the lastcolumn (46 th ) is read out.23 <strong>IS</strong>-<strong>GPS</strong>-<strong>800A</strong>8 June 2010
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