[trebligdivad]

Do you need to fit that many sensors around the edge or can you rotate the ring of fewer sensors?

[ssivark]

You need a full ring of sensors to be receiving at all times. The Caltech design has a rotating element that emits once at each location on the ring. The Midjourney design instead uses the same receiver elements to also emit one at a time, in turns. But wherever the emitter fires from, all the receivers need to be listening.

If you move a single sensor around then you need to multiply the scanning time by the same amount, and repeat the same "experiment" for each measurement position.