How to find the compression method used on an unknown sequence of bytes?
This file contains some repeated long byte sequences. In particular, the 66(decimal)-byte sequence beginning 49 97 CE... occurs many times, and always at an offset that's a multiple of 66.
If you decrypt the file as a bitwise Vigenère cipher with that as the key, the result has a lot of structure. It appears to be divided into 66-byte records with 64 bytes of payload followed by a 2-byte checksum. (I assume it's a checksum because it's a deterministic function of the first 64 bytes, and the first 64 bytes sometimes have simple patterns like 01 01 01... but the last two bytes always look like garbage.)
Beyond that, I can't figure anything out. Notably, while some records consist entirely of recognizable patterns (except the checksum), and some begin with recognizable patterns and end as garbage, none begin as garbage and end recognizably, which makes me think that there may be more to the encryption than a simple xor.