Hi guys

Anyone knows about what kind of sensors are used in speed camera ?

And how do they cover a large area, like the width of a road?

Thanks guys!

 

Hello,

Most times it is radar doppler.
Here is how doppler works:
http://en.wikipedia.org/wiki/Doppler_effect
Here is how radar works:
http://en.wikipedia.org/wiki/Radar
And here the radar doppler:
http://en.wikipedia.org/wiki/Doppler_radar

Bertus

 

Hello,

Most times it is radar doppler.
Here is how doppler works:
http://en.wikipedia.org/wiki/Doppler_effect
Here is how radar works:
http://en.wikipedia.org/wiki/Radar
And here the radar doppler:
http://en.wikipedia.org/wiki/Doppler_radar

Bertus

Any idea why uktrasonic sensor and laser distance sensor are not chosen for this application?

 

Hello,

Laser IS used for speed measurement.
http://en.wikipedia.org/wiki/LIDAR_speed_gun
The laser however has a very narrow beam and needs to be pointed at the object to be measured.

There is more info on trafic speed measurements on this page:
http://en.wikipedia.org/wiki/Speed_limit_enforcement

Bertus

 

The one near my house has inductive sensors in the pavement, similar to traffic light detectors.

ak

 

ultrasonic sensors have too short a range.

 

Some types really are cameras, they use standard optical sensor chips and then process the picture and license plates. These are mostly used in pairs to enforce speed limits throughout a long stretch of road or a tunnel, by calculating the average speed of each vehicle.