[Q:] There are 5 frames in a complete GLONASS navigation message each consisting of 15 strings, and the length of each string is 85 bits. After logging the GLORAWFRAME log, the length of each string was 11 bytes (88 bits), not 85 bits. How can the 85-bit string in the GLORAWFRAME log be extracted?
[A:] There are 3 bits added at the beginning with the string number to follow 8-byte alignment.
For example, consider this string:
In the example string above, the first 8 bits are 00000001 (in binary) which is originally given as 00001 in the raw data.
Adding three extra 0's to the raw data allows the string to follow 8-byte alignment. Because of this, when decoding the data, the first 3 bits can be ignored as they will always be 0.