<< Specs cameras are painted yellow and are fitted into normal camera housings with what looks like a light on the side. As GTB mark says, there have to be a pair of them across a set distance to work out your average speed. >>
disagree.. SPECS camera look like a camera with two round barrels mounted either side of it usually on the left hand side with a blue curved pole or they are mounted on motorway overhead sign.
You sound to be describing Truvelo camera.
Have a look here Daddy.
The Truvelo is now usually yellow rather than blue as shown and the Digital SPECS mounting post is often more elaberate than shown.
GATSO takes picture of rear of car and is instant speed calc
TRUVELO takes picture of front of car and is instant speed calc
SPECS records front number plate as you approach first camera, then again when you pass second camera usually a mile apart and calculates average speed.. issues ticket if over the fresh hold.
No fixed camera works a mile away, only the mobile cameras/laser/radar do that either mounted in a van of late or hand held etc..
Simon