I seem to recall some rules about being able to select the sensor suite based on the drone's device rating, leading to drones of varying sensor arrays (e.g. one could have cameras, another could have ultrasound, yet another could have only audio). It's entirely possible this is the fevered dream of an addled mind, so take it with a grain of salt. However, it stands to reason drones have some way of perceiving the world - what that is would likely be up to the player and the GM. I think having the sensor suite limited by device rating makes sense as a way to limit their sensors (as opposed to saying "all of them").
Best,
-DrZ
EDIT: This specific issues seems to be addressed on the officials:
Here.