There is a camera facing down and just behind it two dark lenses facing down.  Are those two lenses ultrasonic sensors like cars have for backing up obsticle avoidance?  Or are they infrared like what is on the front of the drone?  They are called by both terms in the ads, articles, and manual.

Was my ultrasonic sensor error warning because the ultrasonic system detected fog water particles under it (30 ft hover in 1/4mile visabilty foggy skies)?  Or was my ultrasonic sensor warning because the sensors are really infrared sensors and my fingerprint on one lense was blocking its clear vision?

The bottom sensor is an infrared TOF sensor. Smudging up one lens wouldn't affect the sensors as one is the emitter and the other a receiver; only external particles affects the sensors (fog/clouds) The ultrasonic sensor error is due to the fact that almost all dji drones uses ultrasonic sensor, so dji was too lazy to change the warning for the spark..

Makes sense.  Lenses looked like an infrared system.  Article and advertising mentions ultrasonic sensors as part of the vision positioning system on the bottom of the drone.  No big deal but I like knowing what I am dealing with so it can be maintained.

Gunship9 Posted at 2018-1-22 11:30
Makes sense.  Lenses looked like an infrared system.  Article and advertising mentions ultrasonic sensors as part of the vision positioning system on the bottom of the drone.  No big deal but I like knowing what I am dealing with so it can be maintained.

Sir, flying across fog and cloud will affect VPS system and have the error message. Please ensure that there is no stain on the VPS. You can read our user manual to avoid things that have a bad influence on VPS.