Has anyone experience of using the HC-SR04 ultrasound sensors outside? I built a simple circuit that works perfectly indoors, however when I take the device outside it generates a lot of spurious readings. I haven't been able to figure out what is causing the problem, but my first assumption is some atmospheric conditions interfering with the sensors. Has anyone experienced anything similar?
Are you using the same power supply outdoors as you used indoors?
If you're using a switching regulator it's possible (or so I'd think) it could be generating ultrasonic noise.
Are there machines around in this outdoor area? Bats?
Yes the set up is exactly the same, an Arduino Nano powered by a battery pack and hooked up to the sensors and a piezo buzzer. Indoors it is fine, outdoors it buzzes at 1 second intervals if there is nothing in range. I don't think there are bats in our area. Could be a coding problem, but then I wonder why the effect is only observable outdoors?
Fixed it! It was a coding problem as I suspected. The sensors are working fine now, thanks for all your help.