Please stop everybody!
You are quite right, it is binary data. Thanks to all of the replies, but I think my original question was very badly worded and has confused everybody.
It is binary data that is often/usually not byte-aligned. Converting it to text/ASCII/whatever will result in some fields being spread across two or more bytes. Fields are not necessarily a multiple of whole bytes and may be less than a byte. Fields may be variable length and may also contain several different types of data. Bits may encode one or more binary flags, integers, pointers to end of field, ASCII, Unicode, several flavours of what can only be described as mangled ASCII, mangled ASCII encoded into ten bits (don't ask!), 33 and 9 bit clocks coding up one or more 42 bit clocks, variable length codes, CRCs, FEC codes and probably a lot of stuff I have forgotten.
I am never going to shove this gallimaufry of data into awk or similar!
Thanks again to all, I will slink away now.
Biting the hand that feeds IT
