Customer Service Center

• PosApp (SimGEN / SimREPLAYplus / SimREPLAY)

• Upload Details are contained in the GPS constellation file.
• From the scenario tree go to [GPS constellation-->GPS signal sources file-->Signal control-->Upload details] (see Figure 1)

• The upper section provides data content that applies to the GPS 'Legacy' navigation message
• The lower section (entitled "GPS modernisation data") provides data content that applies to the newer 'CNAV' navigation message.
   
• The user should familiarise themselves with the appropriate GPS ICD:-
  • IS-GPS-200 (for 'legacy' navigation message and CNAV on L2C)
  • IS-GPS-705 (for CNAV on L5)
  • IS-GPS-800 (for CNAV on L1C)
• Use the ICD to understand in more detail each navigation message structure. A basic summary is given below.

LEGACY MESSAGE UPLOAD DETAILS

1. "L1/L2 signal health" & "L1/L2 nav data health"
       - broadcast in subframe 1 for the transmitting SV
       - a summary for other SVs is in subframe 5 and 4
2. "L2 channel code" & "L2 channel flag"
       - broadcast in subframe 1 for the transmitting SV
3. "Anti-spoof (AS) flag"
       - broadcast in the HOW word of every subframe for the transmitting SV
       - a summary for other SVs is in subframe 4
4. "Alert (URA) flag"
       - broadcast in the HOW word of every subframe for the transmitting SV

GPS MODERNISATION UPLOAD DETAILS

1. "L1 health bit" & "L2 health bit" & "L5 health bit"
       - On L2C and L5 they are broadcast in message type 10 for the transmitting SV and then in message types 12, 31 and 37 for the PRN identified in each message type.
       - On L1C they are broadcast in subframe 3 and each reduced almanac packet for the PRN identified in that packet
2. "L1C health bit"
       - broadcast on L1C in subframe 2
3. "URA_oe" & "Integrity status"
       - On the L2C and L5 they are broadcast in message type 10 for the transmitting SV.
       - On L1C they are broadcast in subframe 2
       - Allowed values for URA_oe are provided in the corresponding ICD
4. "URA_oc" & "URA_oc1" & "URA_oc2"
       - On L2C and L5 they are broadcast in message types 30 - 37 for the transmitting SV.
       - On L1C they are broadcast in subframe 2
       - The definitions of possible values for each URA_oc parameter are provided in the corresponding ICD

• "L5 signal health" & "L5 nav data health" (which actually appear in the 'upper' section of the Upload Details page) are deprecated and no longer part of the latest ICDs.
  • Refer back to IS-GPS-200C & IS-GPS-705 (initial release, 30/9/03).
  • They were broadcast on L2C and L5 in message types 3 & 4 for the transmitting SV.
• Although deprecated PosApp can still support these old message types.
• Simply use the L2C and L5 CNAV message sequence control from within the GPS constellation file editor (refer to Figure 1) to add these message types to the default sequence.