Silicon Valley is crawling with startups looking for a piece of the emerging self-driving car business. One of those startups, Aeva, just came out of stealth mode with a big write-up in The New York Times. Its breakthrough: building a single sensor that can determine both the position and velocity of surrounding objects.

Most experts say that the best self-driving cars need a trifecta of sensors: cameras, lidar, and radar. They need all three sensor types because each performs a different function. Cameras can tell you what objects look like but not how far away they are or how fast they're moving. Lidar measures distance, while radar provides a precise estimate of velocity.

This is a bit of an oversimplification, of course. The physics of the situation makes it possible to measure either distance or velocity from either type of electromagnetic wave—there are lidar speed sensors and radar range finders. But in automotive applications, radars are mostly used for low-resolution measurement of vehicle speeds, while lidars are used to build a high-resolution three-dimensional map of the surrounding area.

According to the Times, Aeva's sensor aims to provide high-quality data on both speed and velocity:

Where current lidar sensors send out individual pulses, Aeva’s device sends out a continuous wave of light. By reading the way this far more complex signal bounces off surrounding objects, Mr. Rezk said, the device can capture a far more detailed image while also tracking velocity. You can think of it as a cross between lidar, which is so good at measuring depth, and radar, which is so good at measuring speed. Mr. Rezk also said the device’s continuous wave would provide greater range and resolution than existing lidar devices, deal better with weather and highly reflective objects like bridge railings, and avoid interference with other optical sensors.

The company is less than a year old, and, until today, it was in stealth mode—its website doesn't yet have any details on the technology. So we'll have to wait and see if the company's claims are borne out by independent analysis. But if the new sensor works as advertised, it could make self-driving cars more reliable and affordable.