ultrasonic sensor

[edinrien]

hello...
im try to build a project based on passive sonar.
if there possible that i only use receiver part of ultrasonic sensor??

 

[Sceadwian]

Only if you're trying to listen for bearing failure in electric motors... Ultrasound doesn't travel through air very well, basically line of site. Without something to generate noise ultrasound is not so useful.

 

[umagrama]

You need a transmitter and a receiver for a project unless your project is to trace submarines or whales.

I did a project using a sonar from an old Polaroid (?) camera from the 70's. They had the sonar system for focusing the lenses. My project was a distance sensor, it could calculate how far an object was. Pretty straight forward project and it was fun. Send the wave, measure the time it took to get back, multiply by the twise the speed of the wave and bang...

I bet you could impress the ladies with that.

 

[Mikebits]

He did say passive sonar.

 

[Torben]

I wouldn't know where to start for a passive sonar, except that my bat detector emits a weird sound if I move the mic closer to something or farther away. This happens even if I move it fairly slowly, although it's more noticeable at higher speeds. It also happens if the mic is stationary and the target is moving (I tried that to eliminate the possibility that the sound was wind on the mic).

So I don't know whether this effect could somehow be used to determine the distance to something. I think I could get enough information from the weird sound to indicate how fast something was approaching or receding, but not how far away it is. Also, telling the difference between approaching receding might be tricky without DSP, which I've never done.

Why do you want a "passive" sonar? You don't just mean an ultrasonic listener, do you?


Torben