A lot of you know the feeling: you're driving along, see a flash and realize you just had your picture taken by a automated speed camera. In a few weeks you're probably going to get a ticket in the mail.

But how about getting an advance warning before that camera catches you? It's possible.

Dr. Bill Ross' GPS helps guide him whenever he's on the road.

They're popular devices usually used to steer you in the right direction. But now, some can also steer you away from a photo radar ticket.

"If you set it right, like I have mine set you have plenty of warning," he says.

Here is how it works: Dr. Ross subscribes to a service called Phantom Alert. He can download updated locations of the red light and photo radar cameras.

"Currently we have 110,00 verified locations for US and Canada," says Phantom Alert CEO Joe Scott.

Dr. Ross' GPS knows when he's getting close to one of the cameras. It sounds the alarm to let him know to be careful.

"If someone's is zipping along, forgetting, they've been had," he says.

The service isn't free: it costs $10 a month, or $99 for life.

"The first time you avoid a ticket, the service has paid for itself," Scott says.

As for Dr. Ross, he says it actually makes him a more alert driver.

"These safety precautions are out there and I drive a lot better," Dr. Ross says.

Law enforcement agencies have consistently said they're ok with devices like this warning system because it gets people to pay attention the road and slow down.