How are you modulating a carrier wave if you aren't varying frequency or amplitude?

Would you notice a transmission which consisted of a constant illumination equivalent to that produced by a number of lasers with frequencies that were linked to powers of two? Instead of "On, on, off, off, on, off" separated by time, there would be a single signal which would scope to the same wave as "sin(x)+sin(2x)+sin(16x)" or ""sin(x)+1/2sin(2x)+1/16sin(16x)"

Meanwhile, because we're broadcasting AM broadcasts on many different frequencies, they're trying to figure out
a:Why and how our transmitter is failing intermittently on such a fast scale
b:What our baseline frequency is.
c:How to decode the vast wealth of information they have.

If all we do is notice patterns and automatically ascribe meaning to them, we end up looking at pulsars. For that matter, what evidence do we have that pulsars aren't the result of intelligent communication? Can you construct a 'universal' encoding which could be communicated using only the properties of pulsars? Could you decode such an encoding?