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RoyalTek GPS Receiver REB-2000/REB-12R REV-2000 Operational Manual
18
Payload Data
The payload data follows the message
length. It contains the number of bytes
specified by the message length. The
payload data may contain any 8-bit value.
Where multi-byte values are in the payload
data neither the alignment nor the byte order
are defined as part of the transport although
SiRF payloads will use the big-endian order.
Checksum
The check sum is transmitted high order
byte first followed byte the low byte. This is
the so-called big- endian order
High Byte Low Byte
<0x3F Any value
The check sum is 15-bit checksum of the
bytes in the payload data .The following
pseudo code defines the algorithm used. Let
message to be the array of bytes to be sent
by the transport. Let msgLen be the number
of bytes in the message array to be
transmitted .
Index = first
checkSum = 0
while index < msgLen
checkSum = checkSum +message[index]
checkSum = checkSum AND(210-1)
Input Messages for SiRF Binary
Protocol
Note – All input messages are sent in
BINARY
format
Table 17 SiRF Messages – Input Message List
Hex ASCII Name
0 x 80 128 Initialize Data Source
0 x 81 129 Switch to NMEA Protocol
0 x 82 130 Set Almanac
0 x 84 132 Software Version
0 x 88 136 Mode Control
0 x 89 137 DOP Mask Control
0 x 8A 138 DFPS Control
0 x 8B 139 Elevation Mask
0 x 8C 140 Power Mask
0 x 8D 141 Editing Residual
0 x 8E 142 Steady-State Detection
0 x 8F 143 Static Navigation
0 x 90 144 Clock Status
0 x 91 145 Set DGPS Serial Port
0 x 92 146 Almanac
0 x 93 147 Ephemeris
0 x 95 149 Set Ephemeris
0 x 96 150 Switch Operating Mode
0 x 97 151 Set Trickle Power Parameters
0 x 98 152 Navigation Parameters (Poll)
Initialize Data Source-Message I.D.
128
Table 18 contains the input values for the
following example:Warm start the receiver
with the following initialization data:ECEF
WYZ (-2686727 m,-4304282 m,3851642
m),Clock Offset (75,000 Hz),Time of
Week(86,400 s),Week Number(924),Week
Number(924),and Channels(12). Raw