2-01
DGP000814AAA
GSS6100 and SimCHAN user manual
© Spirent Communications Plc 2005 - 2007
H-5
SBAS Correction Data Files
H.1.2.4
Example of Message Type 1: PRN Mask
The PRN mask appears early in the message and determines which PRN
(satellite) the following correction data is to apply to. The data block for
each message type is 212 bits long. With message type 1, each bit of the
first 210 bits corresponds to its equivalent PRN number i.e. bit 7 is PRN 7.
A maximum of 51 bits of the 210 can be set. The last 2 data bits 211 and
212 determine an Issue of Data PRN (IODP), these 2 bits are set to three
throughout the default message.
In Figure 7-15, 8 satellites are to be considered, PRN 2, 7, 10, 15, 22, 25, 32 and
120.
Figure 7-15 Bit Sequence Message Type 1
0100001001000010000001001000000100.............010...................00000 11
Bit 1 of the 212 bit data block
(Bit 15 of 250 bit message)
IODP
PRN2
Bit 210
PRN10 PRN25
PRN120
PRN32
PRN22
PRN15
PRN7
*.WAS data line for the 212 bit data block of message type 1 is:
Hex:
42 42 04 81 00 00 00 00 00 00 00 00 00
00 01 00 00 00 00 00 00 00 00 00 00 00 3
H.1.2.5
Examples of Message Type 2: Fast Corrections
This message contains clock correction data for all satellites referenced in
the PRN mask. The correction values are determined from the ISCN
(Intentional Satellite Clock Noise) model, which may be enabled and
specified for individual GPS satellites via the GPS Constellation File. If no
error is applied to the correction data then this will accurately reflect the
actual clock error being applied. It is however possible to add an element of
error to the correction data. SBAS satellites are included in this message,