4 ms·

A lot of it has to do with the electrical properties of such a switch. Even older versions of DisplayPort have massive data rates, meaning each electrical sign

A lot of it has to do with the electrical properties of such a switch. Even older versions of DisplayPort have massive data rates, meaning each electrical signal switches many millions of times a second. Also, each signal may have to switch states close to the same time as the other signals, meaning there needs to be some sort of matching between the different signal paths. Add in noise sources from the power supplies, your cell phone, and other sources, and it becomes a challenging physics problem. Not to mention, you don't want those signals leaking out either. At these data rates, wires are both transmitting and receiving antennas. Switches are inherently very mechanical devices, so designing one that can operate in these conditions reliably would be both complex and expensive. Much easier to have some silicon do it for you.

stefan_ 6y ago
Isn't this what SPDT and other RF switches are designed to do? Obviously impractical for a KVM switch, but I wonder if you could build one out of 20 of these.
- bronson 6y ago
  RF switches are fairly expensive and aren't likely to meet the electrical spec anyway. If they're SPDT, you'll probably need at least 10 of them. What's the motivation for using them?
ric2b 6y ago
But I can just pull the plug on any USB 3.0/HDMI/DP cable without any warning to the devices and nothing breaks, why can't a rudimentary switch do the same?
- Ductapemaster 6y ago
  These standards are robust to step-function changes like unplugging and plugging in, through smart electrical, mechanical, and software design. There's a ton of detail here, so if you're interested feel free to DM me. However, the challenges I am referring to above mostly have to do with the steady state operation of the bus, after it has negotiated it's final data rate and is transmitting at full-blast. That's when you run into the transmission problems (eg. radiation of your signals), or your setup just won't allow you to reach the full data rate due to interference.

stefan_ 6y ago

Isn't this what SPDT and other RF switches are designed to do? Obviously impractical for a KVM switch, but I wonder if you could build one out of 20 of these.

bronson 6y ago
RF switches are fairly expensive and aren't likely to meet the electrical spec anyway. If they're SPDT, you'll probably need at least 10 of them. What's the motivation for using them?

ric2b 6y ago

But I can just pull the plug on any USB 3.0/HDMI/DP cable without any warning to the devices and nothing breaks, why can't a rudimentary switch do the same?

Ductapemaster 6y ago
These standards are robust to step-function changes like unplugging and plugging in, through smart electrical, mechanical, and software design. There's a ton of detail here, so if you're interested feel free to DM me. However, the challenges I am referring to above mostly have to do with the steady state operation of the bus, after it has negotiated it's final data rate and is transmitting at full-blast. That's when you run into the transmission problems (eg. radiation of your signals), or your setup just won't allow you to reach the full data rate due to interference.