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SOURce:SCENario:NAVBITS

Function

Sets bits in a navigation message.

The endBitPos - startBitPos +1 LSB of the hexstring are used to replace the bits between startBitPos and endBitPos, so that the endBitPos is aligned with the LSB of the hexstring. In case endBitPos - startBitPos +1 > length(hexstring), the hexstring will be used as a repeating pattern to replace the bits between startBitPos and endBitPos.

Multiple commands may be applied to the same message.

Command Syntax

SOURce:SCENario:NAVBITS IMM, <satID>, <sigtype>, <sfid>, <pageid>, <startBitPos>, <endBitPos>, <hexstring>, <repeat>, <crcflag> [,printflag]

Note

Only available during scenario execution.

Parameter

satID – GPS, Glonass, BeiDou, QZSS and SBAS are supported, the format is explained under SOURce:ONECHN:SATid?.

sigtype – One of the signal types supported by the satellite, allowed values are:

  • For GPS: L1CA, GPSL1CA, L1P, GPSL1P, L1PY, GPSL1PY, L1CAP, GPSL1CAP, L1CAPY, GPSL1CAPY, L2P, GPSL2P, L2PY, GPSL2PY, L2C, GPSL2C, L5, GPSL5
  • Note: The signal types from the same group below share the same navigation bit stream.

    • L1CA, GPSL1CA, L1P, GPSL1P, L1PY, GPSL1PY, L1CAP, GPSL1CAP
    • L2P, GPSL2P, L2PY, GPSL2PY
    • L2C, GPSL2C
    • L5, GPSL5

  • For Glonass: L1, GLOL1, L2, GLOL2
  • Note: The signal types from the same group below share the same navigation bit stream.

    • L1, GLOL1
    • L2, GLOL2
    For Galileo: E1, E5a, E5b
  • For BeiDou: B1, B2,
  • For QZSS: L1CA, L1SAIF (L1SBAS can be also used for L1SAIF)
  • For SBAS: L1SBAS

sfid – For GPS L1 and L2P signals: subframe id

  • For GPS L2C and L5 signals: message type
  • For Glonass: frame id
  • For Galileo E1 and E5b signals: word id
  • For Galileo E5a: page id
  • For BeiDou: subframe id
  • For QZSS L1CA: subframe id
  • For QZSS L1SAIF: message type, where 0 means that the modification is applied on the next message independently of its type
  • For SBAS: message type, where 0 means that the modification is applied on the next message independently of its type

pageid – For GPS L1 and L2P signals: page id and 0 (not relevant) when subframe id is 1-3

  • For GPS L2C and L5 signals: 0 (not relevant)
  • For Glonass: string id
  • For Galileo E1 and E5b signals: 0/1 (even/odd)
  • For Galileo E5a: 0 (not relevant)
  • For BeiDou: page id
  • For QZSS L1CA: page id and 0 (not relevant) when subframe id is 1-3
  • For QZSS L1SAIF: 0 (not relevant)
  • For SBAS: 0 (not relevant)

startBitPos, endBitPos – positions of bits in a navigation message,

Note: For Glonass the bit count starts from LSB, whereas for other messages the bit count starts from MSB.

hexstring – Bit pattern to be set in the message

repeat – 0 if the modification should be applied only once

  • 1 if the modification should be repeated on every message

crcflag – 0 if the CRC/parity does not need to be corrected after the modification

  • 1 if the CRC/parity needs to be correct after the bit modification. With L1SBAS and L1SAIF the preamble will be also maintained.

printflag – 0 if the modified message does not to be logged

  • 1 if the modified message needs to be logged in the execution log. Note that the message is logged only once even if the modification is repeated on every message (repeat flag = 1) .
  • This parameter is optional, the default value is 0.

Example

Set MSB to 1 in 6 bit health (bits 77-82) in subframe 1 of the GPS L1CA message:

SOUR:SCEN:NAVBITS IMM,G23,L1CA,1,0,77,77,1,1,0,1

Example message in the execution log:

06/10/2013 15:00:24 GPS GPS 23 L1CA repeat 1 sfid 1 pgid 0: 
8b0c98374923e24b4108008aaaaabf5555550d5555543ffff2b31048ca1600ffe3b780634a8

Set all bits to 0 in subframe 3 of GPS L1CA message:

sour:scen:navbits IMM,G23,L1CA,3,0,1,300,0,0,0

Set bits 16-119 to 1 in the next QZSS L1SAIF message from satellite J3:

sour:scen:navbits IMM,J3,L1SAIF,0,2,16,119,FF,0,1