I understand the gist of this research: pulsars emit radio waves at regular frequencies, so by monitoring radio waves received from pulsars in the sphere surrou

I understand the gist of this research: pulsars emit radio waves at regular frequencies, so by monitoring radio waves received from pulsars in the sphere surrounding us, we can measure correlated anomalies in their frequencies and infer that they were caused by large gravitational waves that effectively changed the shape of the transmission medium. That makes sense. But this is not measuring the gravitational wave itself. It's measuring the change in trajectory of the radio signals that are "riding" the wave. In the ocean analogy, it would be as if we were surrounded by a circle of floating turrets that each emitted floating darts at regular intervals in all directions. Then we would measure the time it took the darts to reach us, and from that we could infer the size of the waves the darts encountered along the way. But we never actually see the waves, only the darts. So my question is: how can we tell the difference between one really big wave, and many really small waves that would sum to the same effect? In other words, we know there is some waveform(s) that changed the velocity vector of the radio signal. But if there are multiple arrangements of waves that would produce the same change in signal, how do we pick the right arrangement?