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
- 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.
Note: The signal types from the same group below share the same navigation bit stream.
-
- L1, GLOL1
- L2, GLOL2
- For BeiDou: B1, B2,
- For QZSS: L1CA, L1SAIF (L1SBAS can be also used for L1SAIF)
- For SBAS: L1SBAS or SBASL1, L5SBAS or SBASL5
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 SBASL1, SBASL5, 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