HC-SR04 sensor problem

Hello everyone.

I've already made arduino radar (sonar) using an HC-SR04 sensor and it works perfectly fine showing all the detected obstacles on radar screen (using processing IDE). My questions is: Is it possible for HC-SR04 sensor to distinguish 2 or more separate objects? The reason I ask this is because I want my sonar to detect moving objects only, but in order for it to work the sensor needs to know which object is which. Since these are very cheep sensors which use the same frequency and they only measure distance while the additional data inside the returning echo remains hidden (except the time it traveled), I highly doubt that this is possible at all, but I need confirmation from more experienced people. What do you think? If it is somehow possible, any suggestions are welcome on how to do it.

Thank You in advance.

They let you know how long it took for the first echo to return, that's it. So the closest object with it's 30° or so field of "vision" is what you get.

Thanks for your reply. So, basically, there is no way to make it detect only moving objects?

Of course there is. Surely you have seen movies of airport control tower radar displays.

Do multiple scans, and if you observe significant shifts of an echo, either in angular position or distance, from one scan to the next, something is moving.

You don't "tell" the detector to detect only moving objects, you interpret the data returned by the detector. That will usually involve sorting out the desired signal from the noisy background.

You won't be able to do any radar like sweeps with the HC-SR04. The beam is far too wide, and you get to see only one echo even if there are multiple objects in view.

Maxbotix makes some ultrasonic sensors with a fairly narrow beam - 11 degrees or so. Such as this one. Constructing a radar-like sweep display with it would be...an interesting challenge...difficult. :slight_smile:

For one of those sensors you can buy a box full of HC-SR04s...
I suppose they use a much higher frequency sound?

You won't be able to do any radar like sweeps with the HC-SR04.

But the OP did! I think you meant to write "I won't be able ...", because the rest of us are certainly able to do so.

It has been done many, many times, including by me, 18 years ago. And the data can be interpreted.

Furthermore wide beams are not a problem, if you are willing to do the math to deconvolute the scans.

Seen any projects using it to track moving objects, a la air traffic control radar?