Hi All.

My A level Electronics coursework has to be in on Tuesday (as does my Design Technology coursework, nightmare!), can anyone help me with this little problem?

My project is a car reversing aid, using ultrasonics to warn the driver of anything that might jump out and hit his/her Scooby!

My question is, what happens to ultrasonics in the rain or snow? Would I get false alarms because of waves reflecting off falling rain/snow and being detected by the receiver?

Cheers,
Ben

 

At work we use ultra sonic for level measurement , same as what you are doing , our tanks very often give false readings during the cleaning process due to the amount of water and steam in the vessel . So I would say yes that they would be affected by rain and snow .
Hope this helps Dave

 

That may well be true, although at least it would report that you were closer to the wall than you already are, so it would fail safe - you wouldn't actually hit anything.

My guess is that steam is a big deal because it completely fills the space between the sensor and the solid wall that the sound waves bounce off, and affects the speed and amplitude of the wave. If it's raining, the chances of there being a water droplet between the sensor and the wall are relatively low, so your system shouldn't work too badly.

It's a limitation I'm sure you'll be able to document your way out of, rather than having to concede that it won't work as well. It's called marketing

Andy.

 

I'd suggest the sensor is placed as far away from the exhaust as pos due to the steam issue pointed out above. But you knew that any way..