USB Type-C is just the technical name for USB-C. The 400 Series cameras are designed to use USB 3.0.
RealSense USB cameras always come bundled with the USB cable.
I am not aware of any speed advantage gained by using the camera in a USB 3.1 port.
The camera is powered through VBUS power of the USB port and requires 5v. The Vision Processor D4 component in turn powers the depth module. You can read the camera's full technical specifications in its data sheet document.
Long extension cables do not typically work well with RealSense cameras due to the huge volume of camera data that is passed through the cable, using up the bandwidth. Even with high quality premium grade cables, the camera has usually not worked with cables longer than 2 m. There has been suggestion that optical USB cables may extend this range, but this is unverified by Intel lab testing.
The 400 Series cameras have not been available for long enough yet for cable recommendations to have been offered by the community, unfortunately. It is possible that someone may provide feedback as a result of seeing your message.
My opinion is that unless you purchased the highest grade cable possible then you risk the camera not working at cable lengths over 2 m. Even with a top-end cable there would be few guarantees. In over three years of supporting RealSense, I have never come across a person who has been able to make RealSense cameras work with cables longer than 2 m. If it were possible then there probably would have been some reported cases of success by now.
Fwiw, we are successfully using "active" USB 3.0 cables to extend the 1m cable shipped with the D435-cameras. Works nicely, even with two and three cameras.
My apologies for hijacking the thread, but I noticed that "bandwidth" is mentioned in the original post: Are there any guidelines or best-practices for calculating the USB bandwidth-requirements of the D400-cameras? (I know how to calculate size of a frame and multiply this by framerate - I am interested in actual/real-life bandwidth, including protocol-overhead, when streaming depth and rgb.)
Ultimately, we want to drive multiple D435 from a single host and it is useful to be able to understand and estimate this limitation.
I could not find any formal processes for calculating the USB bandwidth of RealSense cameras, unfortunately. As a general rule of thumb though, bandwidth is related to resolution. The lower the resolution being used, the less bandwidth that should be used. The opposite is true for using high resolution.
One of the leaders of Librealsense, Dorodnic, also had this advice in 2016 about multi-camera use in Librealsense: "Using the same USB3 controller for more then one RealSense device is not recommended. Bandwidth of USB3 is limited and you will inevitably lose frames. If you're using separate USB controllers, you will still need a powerful PC or you will have frame drops at the kernel driver level."
I have tested up to four cameras on a single Intel NUC running Ubuntu 16.04. The total amount of image-data must be limited by reducing resolution, framerate and channels (grayscale instead of color), but it does work without losing too many frames. I connected the cams via two separately powered USB-hubs (NUC shuts down otherwise) but I'm still rather impressed by the fact that this works when running the realsense-viewer.
Would anyone from Intel like to comment on Dorodnics advice from 2016? Does this still apply? Have you done any benchmarking in this direction? Any clues to amount of overhead in the protocol?
USB 3.1 Gen 1 and USB 3.0 are basically the same thing. In another word, D400 series is using USB 3.0 connectivity with a Type-C interface. The USB 3.0 (or 3.1 Gen 1) Type-A to Type-C cable is basically the same thing to USB 3.0 A to micro B cable that you use for 200 series RealSense Camera.
Regarding your bandwidth concern, as long as the USB cable you use meets the signal integrity standard, shouldn't be a problem work with the camera.
Just make sure you don't share multiple cameras by one upstream USB 3.0 hub. Sharing cameras directly connect to your CPU is fine though, the main bus designed to support multiple full bandwidth USB 3.0 lines.
3m and 5m industrial grade USB 3.0 cable has been widely used by industrial applications such as machine vision, medical imaging for many years. These applications also require high bandwidth and frame rate transmission as well as RealSense.
Hope this white paper can help a bit.
This message was posted on behalf of Intel Corporation
Thanks for your interest in the Intel® RealSense Technology.
Intel will soon publish a white paper that contains all the information regarding USB bandwidth requirements for the D400 series cameras.
We don't have a publication date yet. We will post a blog on this community when it is available.
Thank you for your patience and understanding.
Intel Customer Support
@Newnex: Thanks for info!
@Josh B: Looking fwd to reading the whitepaper.