HTC earlier this month revealed a 6DOF controller dev kit for the Vive Focus standalone headset. New details have emerged about the device this week.

When HTC revealed the Vive Focus 6DOF controller dev kit earlier this month, the company wasn’t ready to share details. This week at XRDC in San Francisco, the company spoke more about the dev kit and noted that between the Vive Focus and other Vive Wave powered headsets, consumers are likely to see a number of different 6DOF controller tracking technologies accompanying different headsets.

HTC’s Viveport President, Rikard Steiber, said during a presentation today that the Vive Focus 6DOF controller dev kit uses a combination of ultrasonic tracking and IMUs to track the user’s hands. Ultrasonic tracking systems use soundwaves at frequencies above the audible human range for triangulation, typically using a series of receivers to identify differences in timing between ultrasonic sounds emitted by the tracked object.

Steiber noted that the system’s tracking field of view is 180 degrees horizontally and 140 degrees vertically, and that it’s capable of “high accuracy” up to one meter from the headset.

While the Vive Focus ships with a 3DOF controller, the 6DOF controller dev kit includes two new controllers and a large module which is mounted to the headset. US developers can sign up to receive one here.

We haven’t had a chance to try the controller tracking system yet, but aren’t entirely surprised to find that it’s based on ultrasonic tracking considering that it’s among the options offered by Qualcomm’s Snapdragon VRDK, which we understand Vive Focus to be based on.

Ultrasonic tracking is not new by any means; we’ve seen VR trackers based on the technology in recent years, and the tech was employed for similar purposes long before the modern era of VR. Pico Neo was one of the first modern standalone headsets we’ve seen using ultrasonic tracking for 6DOF input, though our hands-on with the headset earlier this year didn’t inspire much confidence in the controller tracking.

Generally speaking, the capabilities of ultrasonic tracking have been considered insufficient as a head-tracking solution for high-end VR headsets, though hand-tracking is less sensitive to latency and inaccuracy, and could prove effective with the right implementation.

Steiber made a point to say that among headsets running Vive Wave (like Vive Focus), there will likely be several different 6DOF hand tracking solutions employed, but from a developer standpoint the platform aims to work seamlessly with all of them.

While the Vive Focus is available in China as a consumer ready product, in the US and elsewhere it’s still a developer kit only. With hand input still in flux, it seems it may remain that way for some time still.