analyzing signal polarization shifts.
bingo.
a second layer, nested within the main signal; possibly.  a picture? product of three primes.
 definitely three dimensions, either a hologram or a two- dimensional picture that moves in time; a movie.
in ancient times when parchment was in short supply people would write over old writing.  it was called a palimpsest.
there's no way of knowing. without a key -- a primer, to help us, maybe never.
we've repeated. a few minutes ago the message cycled back to page one.
no primer.
i don't know. maybe there is a fourth layer in there somewhere, but if there is, i sure as hell can't find it.