Orient ОС-103 [93/244] Bd2rawephemraw bd2 ephemeris

Orient ОС-201 [93/244] Bd2rawephemraw bd2 ephemeris
COMNAV OEM BOARD REFERENCE MANUAL
Chapter 4. Log Messages
ComNav Technology Ltd.
74
CNT-OEM-RM001, Rev 1.8
Field#
Field Type
Data Description
Format
Binary Offset
variable
[CR][LF]
Sentence terminator (ASCII only)
-
-
Note. Length of one subframe almanac is 10 words (30 bits per word, MSB first).
Subframe 4 Page 1~24 and Subframe 5 Page 1~6 contain 30 frames BDS
satellites’ almanac (Refer to Beidou-ICD-1.0 table 5-11-1 and 5-11-2). One word
(30 bits) is split into 4 bytes data (first two bits of 1st byte is unused), then one
almanac subframe data is expressed in 40 bytes as following Figures shows:
4.2.1.8 BD2RAWEPHEM Raw BD2 Ephemeris
Description
This log contains the raw ephemeris of BD2 satellites, and each raw ephemeris message is 400
bytes long. Each ephemeris page is 300 bits long, and the log contains all bits, although some
bits are not used in current definition. For GEO satellites, ephemeris bits are all in sub frame 1,
which is composed of 10 pages, each page is 10 words long and there are 30 bits in each word.
Notice, just higher 150 valid bits are used in page, so all pages are needed to be decoded. For
IGSO and MEO satellites, ephemeris bits are in sub frame 1, 2 and 3 and each sub frame is 10
words long and all 300 bits are valid, the other sub frames are invalid in the log. The page or
sub frame structure in bytes arrays are showed in the below figure. If detailed information
needed, please refer to BD2 ICD.

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