astronomy, pulsars?

Pulsing would produce a sinewave of energy, rather than a burst of radio energy - then nothing for a period of time.
Two objects orbiting each other - first, they'd need to be amazingly close - which means amazingly massive, and second, they'd need to be amazingly strong to hold their shape... and again - it's a *pulse* of energy, not a gradual rise, then gradual fall of light being eclipsed by another object.

Reasonably, the object in question is turning very fast, driving bursts of radio energy.