IS-GPS-800A - US Coast Guard Navigation Center

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S1 POLYNOMIAL:1 + m 1 x + m 2 x 2 + · · · + m 10 x 10 + x 11STAGENUMBERSm 1 m 2 m 3 m 4 m 5 m 6 m 7 m 8 m 9 m 10m 111 2 3 4 5 6 7 8 9 10 11n 1 n 2 n 3 n 4 n 5 n 6 n 7 n 8 n 9 n 10 n 11012 3 4 5 6 7 8 9 10 11INITIALCONDITIONSSHIFT DIRECTIONTAPNUMBERSOUTPUTS2 POLYNOMIAL:1 + x 9 + x 111 2 3 4 5 6 7 8 9 10 11n 1 n 2 n 3 n 4 n 5 n 6 n 7 n 8 n 9 n 10 n 110 12 3 4 5 6 7 8 9 10 11NOTE: S2 POLYNOMIAL IS NEEDED ONLY FOR PRN NUMBERS 64 – 210 AS DESCRIBED IN SECTION 6.3.1.2NOTE: S1 POLYNOMIAL COEFFICIENTS AND INITIAL CONDITIONS ARE GIVEN IN TABLE 3.2-3MSB OF INITIAL CONDITION GIVEN IN TABLE 3.2-3 IS IN STAGE 11FIRST BIT OF THE OUTPUT IS THE MSB OF THE OUTPUT SEQUENCEFOR S1 POLYNOMIAL, m 11 IS EQUAL TO 1Figure 3.2-2. L1C O -Code Generator Configuration16 IS-GPS-800A8 June 2010
3.2.2.2 Non-Standard CodesThe non-standard codes, used to protect the user from tracking an anomalous navigation signal, are not forutilization by the user and, therefore, are not defined in this document. In addition to the SV’s capability toautonomously initiate the broadcast of non-standard codes, the SVs shall also be capable of initiating andterminating the broadcast of NSCP and/or NSCD code(s) independently of each other, in response to a ControlSegment (CS) command.3.2.3 Message CharacteristicsThe following defines the overall message structure of the L1C message, D L1C (t). The data content of the L1Cmessage is defined in Section 3.5.3.2.3.1 L1C Message StructureThe message modulated onto the L1C D signal consists of subframes and frames, as shown in Figure 3.2-3. A frameis divided into three subframes of varying length. Multiple frames are required to broadcast a complete datamessage set to users.Each frame shall consist of 9 bits of “Time of Interval” (TOI) data in subframe 1, 600 bits of “non-variable” clockand ephemeris data with Cyclic Redundancy Check (CRC) in subframe 2, and 274 bits of “variable” data with CRCin subframe 3. The content of subframe 3 nominally varies from one frame to the next and is identified by a pagenumber. The content of subframe 2 is nominally non-variant over a period of multiple frames.Subframe 1 provides 9-bit TOI data that corresponds to the SV time epoch at the start (leading edge) of the nextfollowing frame (reference paragraph 3.5.2). The 9-bit TOI data shall be encoded into 52-symbol code using Bose,Chaudhuri, and Hocquenghem (BCH) code as defined in paragraph 3.2.3.2.Subframes 2 and 3 shall utilize 24-bit CRC parity algorithm as defined in paragraph 3.2.3.3 with a separate CRC foreach subframe. Each of the two subframes (2 and 3) shall be further encoded using Low Density Parity Check(LDPC) Forward Error Correction (FEC) code as defined in paragraph 3.2.3.4. The FEC encoded symbols shall beinterleaved, as defined in paragraph 3.2.3.5, prior to being modulo-2 added to L1C D -code.The resulting 1800 symbols, D L1C (t), representing one message frame, shall be broadcast at 100 symbols per second.17 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: FIXED LENGTH-10223 LEGENDRE SEQUENC
Page 27 and 28: corresponding to MSB = 0. (A SV tra
Page 29 and 30: This code has the following charact
Page 31 and 32: 3.2.3.5 InterleavingThe 1748 encode
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 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
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Table 6.2-1.Legendre Sequence (Octa
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Table 6.2-2 LDPC Submatrix A for Su
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Table 6.2-3. LDPC Submatrix B for S
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Table 6.2-7. LDPC Submatrix T for s
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Table 6.2-7. LDPC Submatrix T for s
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Table 6.2-8. LDPC Submatrix A for s
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Table 6.2-8. LDPC Submatrix A for s
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Table 6.2-9. LDPC Submatrix B for S
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Table 6.2-13. LDPC Submatrix T for
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Table 6.2-16. Number of 1’s in LD
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6.3 Supporting Material6.3.1 Additi
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Table 6.3-1 Additional L1C Ranging
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PRNSignalNo.Table 6.3-2. Additional
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PRNSignalNo.Table 6.3-2 Additional
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IS-GPS-800A - US Coast Guard Navigation Center

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