G sensor related?

[tangopapa]

I've been trying to figure out how in-vehicle cameras calculate the amount of g-force needed to trigger the video recorder on a dash-mounted camera.

Can anyone point me in the right direction? I'm looking for an industrial standard that would define "aggressive acceleration or deceleration" Basically, what is the value needed that would indicate erratic movement in a vehicle...

Any help would be great....camera sites aren't helping me out too much but I'm sure there are some folks here that would know

Thanks

Tim