OK, I read the question .. it's pretty straight forward :
For each of the periods (1 to 8), just check the amplitude of the waveform, and its phase difference with respect to the previous period. Then write the 3-bit symbol from the table, corresponding to it.
E.g., for the first period, the symbol is 001, 'cuz amplitude is A2 and phase difference is 0.
for the second period, the symbol is 010, 'cuz amplitude is A1 and phase difference is 1/(4f).
I won't complete the answer 'cuz that would be a spoiler. Try it yourself and if you can't then I'll try to post complete answer.