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We are using Intel Realsense cameras in our product. Sometimes the USB connection fails completely, sometimes it is USB2 only and the camera cannot work. Someti

We are using Intel Realsense cameras in our product. Sometimes the USB connection fails completely, sometimes it is USB2 only and the camera cannot work. Sometimes a reboot helps, but sometimes power cycling is required. This is without plugging the cable, plugging adds its own unreliability. From reading the product support forums we are not alone. As a SW engineer my interpretation has always been that USB3 speeds are just too high to work really reliably with consumer grade hardware. This article gives technical details that tell me I have been correct.

raxxorrax 6y ago
This has also been a problem with USB2 cameras. The signal rates reach physical limits. A 5m cable is probably too long for high speed applications, most camera vendors say that they support only 3m. But if you have a camera in any rugged device, even a bit of EM (electro magnetism) can ruin your connection.
- cpach 6y ago
  What does EM mean in this context?
  - tW4r 6y ago
    Based on the context I would guess it stands for electromagnetic interference
  - oso2k 6y ago
    Probably short for Electromagnetism or short for EMF which is short for Electro Magnetic Field.
  - segfaultbuserr 6y ago
    Electromagnetism. On the other hand, obviously any electronic circuit, including USB, is electromagnetic. A more accurate choice of word would be EMI (i.e. electromagnetic interference), or EMC problems (i.e. electromagnetic compatibility problems).
MrBuddyCasino 6y ago
Apple/Intel Thunderbolt does not have this problem in my experience. USB has always been the cheapest alternative (remember Firewire?). Add to that the sheer incompetence of the USB committee (see the USB PD spec, or USB Audio) and its a miracle anything works at all.
- izacus 6y ago
  Yeah, we remember FireWire. And all the burned out FW ports due to poor power regulation on cameras and devices. I don't think I've ever seen a connection protocol more likely to damage a device on either end of the connection. USB is a massive imporovement here.
  - mixmastamyk 6y ago
    > FireWire --> burned out ports Sounds like it delivered what it said on the tin!
  - marcan_42 6y ago
    FireWire is a much better design than USB in many ways. I still use a FireWire audio interface purchased not that long ago (though now it has to go through a Thunderbolt adapter). The problem with USB 1 and 2 is that it was designed by insane committee. This resulted in stuff like those versions not using true differential signaling (like USB3 does) even though that was common technology at the time. Instead they have end of packets delimited by single-ended conditions. That, coupled with a single ground wire for power and data makes for a world of ground loop issues. And then they made the frame rate 1kHz, which is right in the peak of human hearing sensitivity. And so, USB's terrible design is single-handedly responsible for a huge amount of, even most, noise and interference issues in audio systems involving it. Especially in low cost consumer hardware, but it has made its way into many professional productions. Any time you hear a constant 1kHz beep of interference, mixed with some fuzzy crackling, nine times out of ten that's a ground loop with USB and audio involved. It's everywhere once you listen closely. Headphone output on your laptop or phone is noisy when you access a USB drive, or has a 1k beep? USB. USB audio widget has background fuzz and a beep? USB. Slight 1k beep in the background of a news cast? Someone had the bright idea of using USB somewhere along the line. It didn't have to be this way. Ethernet, SATA, plenty of other protocols use proper differential signaling and don't have this issue. How to do this properly was well established long before USB existed. And to add insult to injury, while USB 2 specifies a transaction translator, so you can run USB 1 devices on a USB 2 bus, USB 3 does not. And so, while USB 3 devices don't have this problem any more, you can't plug in a USB 2 device into a USB 3 bus or a USB 3 hub. And nobody uses USB 3 for low channel count audio interfaces, so this problem will remain forever. Oh sure, you can plug it into a USB 3 port, which is actually a USB 3 port and a USB 2 port in one. And you can plug it into a hub labeled "USB 3" which actually has a whole USB 2 hub along side it in parallel. The communication from USB 2 devices remains USB 2 all the way to the host. And so, not only do USB 2 devices only get 480Mbps of total bandwidth on a USB "3" hub (minus a ton of overhead, because the protocol is terrible), it doesn't fix this issue! And did I mention USB 2 is impossible to galvanically isolate in any kind of cost-effective way? I could go on and on about how the polled architecture causes performance bottlenecks, about how it's impossible to tunnel without unfixable corner cases, about how its latency requirements preclude lots of innovative ideas, about how the descriptor and device inquiry protocols are practically designed to guarantee that implementations are vulnerable and have exploitable bugs (yes, your USB stack is vulnerable. They all are. This is how the PS3 got hacked. And the Switch. And tons of other devices. USB developers like me know misbehaving USB devices crash hosts all the time). I don't like USB.
ladberg 6y ago
I've had nearly the same experience! I was working on a project for a robotics class and my team could not figure out why our object tracking went from 30fps to ~5fps seemingly randomly. It turns out the USB3 cable wasn't fully plugged in and couldn't make full contact so it was running on USB2 and didn't have the bandwidth to send the video at 30fps. It took a while to debug because I was absolutely convinced the slowdown was a software or GPU issue. After all, wouldn't you expect most digital ports to be binary: either be plugged in or not? It turns out with USB3 there's a third state.
- raxxorrax 6y ago
  Full HD raw image data nets you about 5.something FPS on ~480 mbit/s USB2, which already hits physical limits. Higher standards basically just increase the number of data lanes, but we still call that serial.
- rangibaby 6y ago
  > After all, wouldn't you expect most digital ports to be binary: either be plugged in or not? It's always a good idea to have a known-good extra cable or two and laptop that you know has good ports. All the time and frustration you will save is definitely worth the hassle.
- Isthatablackgsd 6y ago
  > it was running on USB2 and didn't have the bandwidth to send the video at 30fps. Mmm, I am surprised about that because USB 2.0 is fully capable of 1080p60 without issues. I have Logitech C910 and it does 1080p60 flawlessly. I wonder if it is not actually 2.0 but USB 1.1 which made sense since the transfer rate is abysmally low (1.1 does up to 12 Mbps, 2.0 is up to 480 Mbps). But again, computers does have their quirks and can do weird & strange things that seem impossible but it is possible.
  - usr1106 6y ago
    > Mmm, I am surprised about that because USB 2.0 is fully capable of 1080p60 without issues. I have Logitech C910 and it does 1080p60 flawlessly. I wonder if it is not actually 2.0 but USB 1.1 which made sense since the transfer rate is abysmally low (1.1 does up to 12 Mbps, 2.0 is up to 480 Mbps). I am not who you were responding to, but I can confirm that at 480 Mbps our Intel Realsense does not work, 5000 Mbps are mandatory. We use an Infrared stereo mode at 30 fps. I am not a my desk now and don't remember the exact details by heart.
colechristensen 6y ago
> As a SW engineer my interpretation has always been that USB3 speeds are just too high to work really reliably with consumer grade hardware. This article gives technical details that tell me I have been correct. The last section of the article is the most relevant: the hardware, tools, and documentation for USB3 are of mediocre quality. The whole history of moving bits over cables is adding and adapting tricks for getting more and more data through, we’ve always been at the point where poorly implemented solutions would cause problems, and we’re several orders of magnitude away from it being possible for a novice to implement a hardware and software solution from scratch (bit banging a serial interface on a microcontroller GPIO is possible for a reasonable person to do in a week to achieve less than a megabit connection). Super fast data rates are all over and most of them are very reliable, USB isn’t up to the same quality. You can make any speed reliable and fool proof, you just have to do it.
- segfaultbuserr 6y ago
  +1. It's true that designing an USB 3.0 PHY/controller is a serious challenge, and bad signal integrity in PCB design can cause many problems, but almost nobody implements one's own USB transceiver or controller from scratch. They're all standard off-the-shelf chips. If the PCB design is careful and a good cable is used, Layer 1 should be relatively stable. A large number of problems appear to be bad hardware compliance, documentation, firmware or driver. For example, I have a PC with an early Renesas USB 3.0 controller. Once in a while, the controller could become completely unresponsive. The reason was that the controller has a firmware bug, and you can actually get some reverse-enginnered firmware update tool on GitHub to fix it.
  - jk700 6y ago
    Bad hardware compliance is only part of the problem. With higher speeds all the user facing stuff, like cables, connectors, power without noise - all start to matter too. You know how 100 mbit ethernet works well even with crappy connectors and crappy wires, you literally don't need even a twisted pair for it, but pushing gigabit ethernet over that doesn't work reliably anymore or even at all. It's very much a universal problem with higher speeds. And the notion that "you can make any speed reliable and fool proof" is just absurd denying physics.
echelon 6y ago
> We are using Intel Realsense cameras in our product. That's an interesting domain. What are you working on? Any reason for choosing Realsense over Azure Kinect or other sensors?
- kypro 6y ago
  As someone who was involved in a RealSense project I might be able to answer... Firstly, RealSense cameras are really affordable. I think the cameras we were using were around $80 a piece. Cost was an important consideration for us because we were building a multi camera device and to do something similar with Azure Kinect would have cost us several thousand dollars. Another thing we like was how great the Intel RealSense SDK is. They have official wrappers for multiple languages along with sample code to get you started. The RealSense ecosystem is quite healthy too – at least for a niche technology. RealSense cameras have a proven track record in various commercial devices and the development forums are fairly active. We found we could find answers to most common questions and problems we had. Another nice thing about RealSense is that they have a great range of cameras so they have something perfectly suited for every application. For example, some of their cameras use stereo vision while others use LIDAR or structured light. They also use the same SDK for every camera which makes swapping out cameras fairly easy. We were using structured light cameras, but we were able to swap them out with Stereo and LIDAR cameras with no problems at all. Azure Kinect looks interesting. I've wanted to play around with one of a while, although given its price and feature set it wouldn't have been the right camera for us. It's probably a good all-rounder for general robotics / vision projects though.
tinus_hn 6y ago
If it starts working again after a reboot it’s a problem that can be solved in software. It’s just hard so consumers instead have been trained to accept unreliability.
- tonyedgecombe 6y ago
  Consumers drive this by buying the cheapest device that just about works.
  - Pet_Ant 6y ago
    Manufacturers aide this by not making their devices apples-to-apples comparable and using brand specific marketing terms. Worrying about buying something from a better brand that is the same thing but marked up is real.
swiley 6y ago
IMO: It's not the speed that's the problem, lots of consumer hardware has very fast networks/buses like ethernet. It's the huge number of states and the communication required to negotiate them.
rubicks 6y ago
I can always rely on our Intel Realsense cameras -- to magically transform themselves into USB 2.1 devices after a couple hours' use.

raxxorrax 6y ago

This has also been a problem with USB2 cameras. The signal rates reach physical limits. A 5m cable is probably too long for high speed applications, most camera vendors say that they support only 3m. But if you have a camera in any rugged device, even a bit of EM (electro magnetism) can ruin your connection.

cpach 6y ago
What does EM mean in this context?
- tW4r 6y ago
  Based on the context I would guess it stands for electromagnetic interference
- oso2k 6y ago
  Probably short for Electromagnetism or short for EMF which is short for Electro Magnetic Field.
- segfaultbuserr 6y ago
  Electromagnetism. On the other hand, obviously any electronic circuit, including USB, is electromagnetic. A more accurate choice of word would be EMI (i.e. electromagnetic interference), or EMC problems (i.e. electromagnetic compatibility problems).

MrBuddyCasino 6y ago

Apple/Intel Thunderbolt does not have this problem in my experience. USB has always been the cheapest alternative (remember Firewire?). Add to that the sheer incompetence of the USB committee (see the USB PD spec, or USB Audio) and its a miracle anything works at all.

izacus 6y ago
Yeah, we remember FireWire. And all the burned out FW ports due to poor power regulation on cameras and devices. I don't think I've ever seen a connection protocol more likely to damage a device on either end of the connection. USB is a massive imporovement here.
- mixmastamyk 6y ago
  > FireWire --> burned out ports Sounds like it delivered what it said on the tin!
- marcan_42 6y ago
  FireWire is a much better design than USB in many ways. I still use a FireWire audio interface purchased not that long ago (though now it has to go through a Thunderbolt adapter). The problem with USB 1 and 2 is that it was designed by insane committee. This resulted in stuff like those versions not using true differential signaling (like USB3 does) even though that was common technology at the time. Instead they have end of packets delimited by single-ended conditions. That, coupled with a single ground wire for power and data makes for a world of ground loop issues. And then they made the frame rate 1kHz, which is right in the peak of human hearing sensitivity. And so, USB's terrible design is single-handedly responsible for a huge amount of, even most, noise and interference issues in audio systems involving it. Especially in low cost consumer hardware, but it has made its way into many professional productions. Any time you hear a constant 1kHz beep of interference, mixed with some fuzzy crackling, nine times out of ten that's a ground loop with USB and audio involved. It's everywhere once you listen closely. Headphone output on your laptop or phone is noisy when you access a USB drive, or has a 1k beep? USB. USB audio widget has background fuzz and a beep? USB. Slight 1k beep in the background of a news cast? Someone had the bright idea of using USB somewhere along the line. It didn't have to be this way. Ethernet, SATA, plenty of other protocols use proper differential signaling and don't have this issue. How to do this properly was well established long before USB existed. And to add insult to injury, while USB 2 specifies a transaction translator, so you can run USB 1 devices on a USB 2 bus, USB 3 does not. And so, while USB 3 devices don't have this problem any more, you can't plug in a USB 2 device into a USB 3 bus or a USB 3 hub. And nobody uses USB 3 for low channel count audio interfaces, so this problem will remain forever. Oh sure, you can plug it into a USB 3 port, which is actually a USB 3 port and a USB 2 port in one. And you can plug it into a hub labeled "USB 3" which actually has a whole USB 2 hub along side it in parallel. The communication from USB 2 devices remains USB 2 all the way to the host. And so, not only do USB 2 devices only get 480Mbps of total bandwidth on a USB "3" hub (minus a ton of overhead, because the protocol is terrible), it doesn't fix this issue! And did I mention USB 2 is impossible to galvanically isolate in any kind of cost-effective way? I could go on and on about how the polled architecture causes performance bottlenecks, about how it's impossible to tunnel without unfixable corner cases, about how its latency requirements preclude lots of innovative ideas, about how the descriptor and device inquiry protocols are practically designed to guarantee that implementations are vulnerable and have exploitable bugs (yes, your USB stack is vulnerable. They all are. This is how the PS3 got hacked. And the Switch. And tons of other devices. USB developers like me know misbehaving USB devices crash hosts all the time). I don't like USB.

ladberg 6y ago

I've had nearly the same experience! I was working on a project for a robotics class and my team could not figure out why our object tracking went from 30fps to ~5fps seemingly randomly. It turns out the USB3 cable wasn't fully plugged in and couldn't make full contact so it was running on USB2 and didn't have the bandwidth to send the video at 30fps. It took a while to debug because I was absolutely convinced the slowdown was a software or GPU issue. After all, wouldn't you expect most digital ports to be binary: either be plugged in or not? It turns out with USB3 there's a third state.

raxxorrax 6y ago
Full HD raw image data nets you about 5.something FPS on ~480 mbit/s USB2, which already hits physical limits. Higher standards basically just increase the number of data lanes, but we still call that serial.
rangibaby 6y ago
> After all, wouldn't you expect most digital ports to be binary: either be plugged in or not? It's always a good idea to have a known-good extra cable or two and laptop that you know has good ports. All the time and frustration you will save is definitely worth the hassle.
Isthatablackgsd 6y ago
> it was running on USB2 and didn't have the bandwidth to send the video at 30fps. Mmm, I am surprised about that because USB 2.0 is fully capable of 1080p60 without issues. I have Logitech C910 and it does 1080p60 flawlessly. I wonder if it is not actually 2.0 but USB 1.1 which made sense since the transfer rate is abysmally low (1.1 does up to 12 Mbps, 2.0 is up to 480 Mbps). But again, computers does have their quirks and can do weird & strange things that seem impossible but it is possible.
- usr1106 6y ago
  > Mmm, I am surprised about that because USB 2.0 is fully capable of 1080p60 without issues. I have Logitech C910 and it does 1080p60 flawlessly. I wonder if it is not actually 2.0 but USB 1.1 which made sense since the transfer rate is abysmally low (1.1 does up to 12 Mbps, 2.0 is up to 480 Mbps). I am not who you were responding to, but I can confirm that at 480 Mbps our Intel Realsense does not work, 5000 Mbps are mandatory. We use an Infrared stereo mode at 30 fps. I am not a my desk now and don't remember the exact details by heart.

colechristensen 6y ago

> As a SW engineer my interpretation has always been that USB3 speeds are just too high to work really reliably with consumer grade hardware. This article gives technical details that tell me I have been correct. The last section of the article is the most relevant: the hardware, tools, and documentation for USB3 are of mediocre quality. The whole history of moving bits over cables is adding and adapting tricks for getting more and more data through, we’ve always been at the point where poorly implemented solutions would cause problems, and we’re several orders of magnitude away from it being possible for a novice to implement a hardware and software solution from scratch (bit banging a serial interface on a microcontroller GPIO is possible for a reasonable person to do in a week to achieve less than a megabit connection). Super fast data rates are all over and most of them are very reliable, USB isn’t up to the same quality. You can make any speed reliable and fool proof, you just have to do it.

segfaultbuserr 6y ago
+1. It's true that designing an USB 3.0 PHY/controller is a serious challenge, and bad signal integrity in PCB design can cause many problems, but almost nobody implements one's own USB transceiver or controller from scratch. They're all standard off-the-shelf chips. If the PCB design is careful and a good cable is used, Layer 1 should be relatively stable. A large number of problems appear to be bad hardware compliance, documentation, firmware or driver. For example, I have a PC with an early Renesas USB 3.0 controller. Once in a while, the controller could become completely unresponsive. The reason was that the controller has a firmware bug, and you can actually get some reverse-enginnered firmware update tool on GitHub to fix it.
- jk700 6y ago
  Bad hardware compliance is only part of the problem. With higher speeds all the user facing stuff, like cables, connectors, power without noise - all start to matter too. You know how 100 mbit ethernet works well even with crappy connectors and crappy wires, you literally don't need even a twisted pair for it, but pushing gigabit ethernet over that doesn't work reliably anymore or even at all. It's very much a universal problem with higher speeds. And the notion that "you can make any speed reliable and fool proof" is just absurd denying physics.

echelon 6y ago

> We are using Intel Realsense cameras in our product. That's an interesting domain. What are you working on? Any reason for choosing Realsense over Azure Kinect or other sensors?

kypro 6y ago
As someone who was involved in a RealSense project I might be able to answer... Firstly, RealSense cameras are really affordable. I think the cameras we were using were around $80 a piece. Cost was an important consideration for us because we were building a multi camera device and to do something similar with Azure Kinect would have cost us several thousand dollars. Another thing we like was how great the Intel RealSense SDK is. They have official wrappers for multiple languages along with sample code to get you started. The RealSense ecosystem is quite healthy too – at least for a niche technology. RealSense cameras have a proven track record in various commercial devices and the development forums are fairly active. We found we could find answers to most common questions and problems we had. Another nice thing about RealSense is that they have a great range of cameras so they have something perfectly suited for every application. For example, some of their cameras use stereo vision while others use LIDAR or structured light. They also use the same SDK for every camera which makes swapping out cameras fairly easy. We were using structured light cameras, but we were able to swap them out with Stereo and LIDAR cameras with no problems at all. Azure Kinect looks interesting. I've wanted to play around with one of a while, although given its price and feature set it wouldn't have been the right camera for us. It's probably a good all-rounder for general robotics / vision projects though.

tinus_hn 6y ago

If it starts working again after a reboot it’s a problem that can be solved in software. It’s just hard so consumers instead have been trained to accept unreliability.

tonyedgecombe 6y ago
Consumers drive this by buying the cheapest device that just about works.
- Pet_Ant 6y ago
  Manufacturers aide this by not making their devices apples-to-apples comparable and using brand specific marketing terms. Worrying about buying something from a better brand that is the same thing but marked up is real.

swiley 6y ago

IMO: It's not the speed that's the problem, lots of consumer hardware has very fast networks/buses like ethernet. It's the huge number of states and the communication required to negotiate them.

rubicks 6y ago

I can always rely on our Intel Realsense cameras -- to magically transform themselves into USB 2.1 devices after a couple hours' use.