There is great excitement in the astronomy community. The search for extraterrestrial intelligence is finally bearing fruit. A strong clear repeating signal is being received from a not so distant star. The pattern being transmitted is as follows.
A AB AACABB ABA AABCABBB AAACABBA ABAB AABBCABBBB
A represents a high pitch tone, B a low pitch tone, and C a tone that oscillates rapidly between the two.
The message lasts for roughly 14 seconds, then stops for about half an hour before repeating again. The time between each repetition is decreasing by about 35 seconds each time.
After the expected duration the message changes.
The original message is still present but when it ends a new message starts after a few second pause.
This new message is much longer than the first and with different tones, each a a different frequency.