Tesla chief Elon Musk today promised an update to Autopilot within the next two weeks. The radar-based upgrade, he said during a Sunday conference call with reporters, will provide a "dramatic improvement in the safety" of Tesla's Model S and X electric vehicles.

It will also require drivers to be more attentive and prevent them from completely ignoring the road.

Radar was added to all Tesla vehicles in October 2014; Autopilot technology was introduced at the same time but not activated for another year.

At the time, radar "was only meant to be a supplementary sensor to the primary camera and image processing system," Tesla said today. Since then, radar technology has improved enough that Tesla can use it "as a primary control sensor without requiring the camera to confirm visual image recognition."

Using radar will provide "an additional level of sophistication," Musk said during the call. It will, for example, be able to look beyond the car in front of you by bouncing signals underneath and around the vehicle ahead. LiDAR, a self-driving car tech used by some of Telsa's rivals, cannot do that, Musk said, which is one of the reasons Tesla has avoided it.

To prevent unnecessary braking (or crashes), Tesla vehicles will use fleet learning. "Initially, the vehicle fleet will take no action except to note the position of road signs, bridges and other stationary objects, mapping the world according to radar," Tesla says. "The car computer will then silently compare when it would have braked to the driver action and upload that to the Tesla database. If several cars drive safely past a given radar object, whether Autopilot is turned on or off, then that object is added to the geocoded whitelist."

That database is more about cataloguing dense objects to avoid. It doesn't matter what the object is, Musk says—"multi-car pileup, a truck crossing the road, an alien space ship"—the car "just knows that there's something dense that it's going to hit and it should not hit that."

If Autopilot is turned off, the car will still operate in emergency braking mode. If it senses you are about to crash, the Tesla will take over at the last second and try to stop a collision. If you have Autopilot enabled, that intervention will occur sooner.

Musk also promised a more robust warning system inside the car if the vehicle detects that you're not paying attention. Technically, you are still supposed to keep your hands on the wheel when Autopilot is engaged, as the system is not completely autonomous. But not all drivers heed this warning. So with the update, drivers who receive an audible alarm for not having their hands on the wheel more than three times in an hour will have to park and restart the car in order to re-enable semi-autonomous functions.

The frequency of those alerts, Musk said, will depend on the car's speed. If you're in stop-and-go traffic, where the car is traveling at 8mph or less, you probably won't get any alerts. If you're traveling less than 45mph, the longest you can go without an alert is five minutes. If you are going faster than 45mph, you'll get an alert every minute if there's nothing in front or you or three minutes if you're following a car since Autopilot is more accurate when you have a vehicle ahead.

Musk remarked that it's often the most experienced Tesla users who encounter alerts; new Autpilot users are very tentative and usually pay attention. As people get more comfortable, they get more relaxed, and that can have deadly consequences.

This update, for instance, comes after the death of Joshua Brown, a Florida man who died after his Tesla, operating in Autopilot mode, crashed into a truck. It has prompted a regulatory review of Tesla's technology, though the car maker says Brown's accident happened when a semi crossed "both lanes of a divided highway in front of an oncoming car, [which] presented a challenging and unexpected emergency braking scenario for the driver to respond to."

When asked today if the radar system could have saved Brown's life, Musk said "we believe it would have," though these things "cannot be said with absolute certainty."

Autopilot "would see a large metal object across the road and knowing that there is no overhead road sign in that position, it's not a white-listed situation, it would brake," Musk said.

Autopilot, meanwhile, is not the only thing Musk has been dealing with lately. He tweeted this week that it has been an "unusually difficult couple of weeks," from the explosion of a SpaceX rocket to "flack" about Tesla's SolarCity acqusition. "One of the worst weeks ever, really," Musk admitted today.

Hopefully the rollout of Software 8.0 goes a bit smoother; look for it to arrive worldwide via an over-the air update in the next one to two weeks.