Ultrasonic Application Question

Is it possible to use an Ultrasonic sensor to measure speed?

I was thinking of taking two samples, then using the distance obtained from each sample and the time measured between each sample to calculate the speed.

Is this possible?

I want to try and make a home made speed sensor hand speed sensor that I can use to pick up the speed of vehciles travelling toward the sensor.

Thank you,

Sounds doable, but there's only one way to find out for sure- give it a whirl and see.

Is this possible?

What is the range of your ultrasonic sensor? Most have relatively small ranges, because they are designed for use indoors.

What kinds of speeds are you talking about? What kinds of vehicles? What distances?

The sensor is HC-SR04, if this isn't suitable, I can always buy another.

I want to use it to detect the speed of cars and trucks. Thank you.

From the data sheet:

Ultrasonic ranging module HC - SR04 provides 2cm - 400cm non-contact
measurement function

A max of 4 meters is probably not going to work. You’d have to have a good place to place the sensor, so it got a head-on reading of the car/truck distance.

You’d need to determine how long the sensor takes to send a pulse, and get a response back. The speed of sound is known, so the math isn’t that difficult. In that time, how far has the car/truck moved?

How quickly can you send another pulse, and get another reading? How far has the car/truck moved in that time?

How many readings can you take while the car/truck moves 4 meters?

Ty for reply, any suggestions on an alternative sensor that could be suitable?

any suggestions on an alternative sensor that could be suitable?

Ask any cop with a radar gun. Or, is that bobby in your part of the world? Do they have radar guns?

They do have radar guns, but I doubt any of them know whats in it.

SPlatten: They do have radar guns, but I doubt any of them know whats in it.

But I'm willing to bet that Mr. Google does.

http://www.bbc.co.uk/insideout/southwest/series7/speed-cameras.shtml

Static cameras tend to use Doppler, but camera vans and handheld are normally laser TOF.

http://www.element14.com/community/thread/26112/l/hardware--using-cheap-doppler-radar-modules

Use of Doppler effect can be used for ultrasonic. Current uses are in the medical area. You would need a fairly strong ultrasonic transmitter to be used for cars if done a longer ranges. Better to use X or K or Ka band RADAR or LASER. Home built RADAR projects used to be found in old electronics rags, or in old electronics projects books. Same goes for LASER projects.

Use of Doppler effect can be used for ultrasonic. Current uses are in the medical area.

But not with pre-built TOF units, like the HC-SR04