NavCom LAND-PAK Rev.N - Manual (Page 16)

Technical Reference Manual Rev. N
Blk = All; Blu = IOP w/Internal Radio ; Red = IOP & LBM ; Grn = Engine only 14
Parameter Words
Message Parameters are referred to as Parameter Words, (Wn). Parameter Words follow IEEE
convention and Intel byte order (Little Endian). Bits within a Parameter Word are designated
Bn, where B0 is the LSB. Exception for U24 and S24, which are low, middle and high.
Little Endian - the low-order byte of the number is stored in memory at the lowest address, and
the high-order byte at the highest address. (The little end comes first.)
Example, a 4 byte LongInt:
Byte3 Byte2 Byte1 Byte0
will be arranged in memory as follows:
Base Address+0 Byte0
Base Address+1 Byte1
Base Address+2 Byte2
Base Address+3 Byte3
Intel processors (those used in PC's) use "Little Endian" byte order.
Big Endian - the high-order byte of the number is stored in memory at the lowest address, and
the low-order byte at the highest address. (The big end comes first.)
Example:
Base Address+0 Byte3
Base Address+1 Byte2
Base Address+2 Byte1
Base Address+3 Byte0
Motorola processors (those used in Mac's) use "Big Endian" byte order.
Measurements:
L1 Carrier phase measurements at L1
C/A C/A code phase measurements at L1
P1 P(Y) code phase measurements at L1
L2 Carrier phase measurements at L2
P2 P(Y) code phase measurements at L2
Protocol
General message format:
Function Length Hex Value Byte Count
STX (Start Transmission) U08 0x02 -
N/A Preamble (1) U08 0x99 -
Preamble (2) U08 0x66 -
Command ID U08 1
Inclusive
Msg. Len. U16 3
MESSAGE variable x
CKSUM U08 1
ETX (End Transmission) U08 0x03 - N/A