NavCom LAND-PAK Rev.N - Manual (Page 114)

Technical Reference Manual Rev. N
Blk = All; Blu = IOP w/Internal Radio ; Red = IOP & LBM ; Grn = Engine only 112
0x81 - Packed Ephemeris Data - 86 bytes
Record
Usage Command - No
Response - Yes Input: Not used;
Output: reports satellite ephemeris
Ref Message Field Description Data Type Units Range Scale
Byte
Count
STX 02 (hex) U08 1
PRA1 99 (hex) U08 1
PRA2 66 (hex) U08 1
ID 81 (hex) U08 1
Length 0x0056 U16 2
W1 SV ID (PRN) U08 1-32 1
W2 GPS Week Number of Collection U16 0 - 65535 2
W3 GPS Time of Week of Collection U32 Seconds 0 - 604800 4
W4 IODC U16 2
W5
Sub-frame 1 data. Satellite Data
Stream with parity bits removed
U08[24] 1[24]
W6
Sub-frame 2 data. Satellite Data
Stream with parity bits removed
U08[24] 1[24]
W7
Sub-frame 3 data. Satellite Data
Stream with parity bits removed
U08[24] 1[24]
W8 Reserved U08 1
CKSM Checksum U08 1
ETX 03 (hex) U08 1
For details on W5 through W7, refer to the GPS System Specification (ICD-GPS-
200) for words 3 through 10 with the parity bits removed. (Each word contains 30
bits; but the last 6 bits and parity have been removed to leave 24 bits.)