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D Logs summary
MiLLennium Command Descriptions Manual 169
RALA/B Raw Almanac
Almanac and health data are contained in subframes four and five of the satellite broadcast message. Subframe
four contains information for SVs 25-32, as well as ionospheric,
UTC and SV configuration data. Subframe five
contains information for
SVS 1-24.
Subframes four and five each contain 25 pages of data, and each page contains ten 30-bit words of information as
transmitted from the satellite. The
RALA/B log outputs this information with parity bits checked and removed (ten
words - 24 bits each). The log will not be generated unless all ten words pass parity.
This log will alternately report each page from subframes four and five as they are collected. Logging this log
onnew would be the optimal logging rate to capture data from pages in subframes four and five as they are received.
RALA logs contain a hex representation of the raw almanac data (one of the possible 25 pages of either subframe 4
or 5).
RALB contains the raw binary information.
RALA
Structure:
Example:
$RALA,7,16,8B0A54852C964C661F086366FDBE00A10D53DA6565F2503DD7C2AACBFED3
*05[CR][LF]
RALB
Format: Message ID = 15 Message byte count = 52
$RALA chan # prn subframe *xx [CR][LF]
Field # Field type Data Description Example
1 $RALA Log header $RALA
2 chan # Channel number collecting almanac data (0-11) 7
3 prn PRN of satellite from which data originated 16
4 subframe Subframe 4 or 5 of almanac data
(60 hex characters)
8B0A54852C964C661F086366FDBE00A
10D53DA6565F2503DD7C2AACBFED3
5 *xx Checksum *05
6 [CR][LF] Sentence terminator [CR][LF]
Field # Data Bytes Format Units Offset
1 Sync 3 char 0
(header) Checksum 1 char 3
Message ID 4 integer 4
Message byte count 4 integer 8
2 Channel number, 0-11 4 integer 12
3 PRN number, 1-32 4 integer 16
4 Almanac data, data [30] 30 char 20
5 Filler bytes 2 char 50