3 ms·

Sorry but not true. To get full bandwidth really limits how long the cable can be. Like I don't think you'll find 40Gbps cables longer than about 0.5m. This is

by cletus 5y ago

Sorry but not true. To get full bandwidth really limits how long the cable can be. Like I don't think you'll find 40Gbps cables longer than about 0.5m. This is more expensive too (eg there are generally chips in the plugs at either end to handle attenuation). But there's obviously a use case for cables longer than that. It is true that we have cables that support data but not power and power but not data or data at different bandwidths and so on. It's a mess. But it's not a case of simply choosing not to support optional features.

danhor 5y ago
The Apple Thunderbolt 3 Pro Cable (2 m) is one of the only cables that can support everything usb-c over such a long distance [1]. But that costs 129$, which just wouldn't work for smartphone charging for which cables (usb-c 2.0 & 60w, the least you can do while still being spec-compliant) cost 7$. I think I haven't seen such a clear & easy to grasp demonstration of tradeoffs anywhere else. [1] For the longest time, this was the only cable to do it all. I think more are available now, but they're still very much non-affordable.
SAI_Peregrinus 5y ago
No, it's a matter of expense. It's possible to embed a redriver in the cable every 0.5m, and thus get longer cables at full speed. They're just very, very expensive. There are three alternatives: one cable type that does everything and is easy to use (but gets expensive quickly as it gets longer), multiple cable types that each do somewhat different things but use identical connectors, or multiple cable types that each do somewhat different things and use different connectors. The USB-IF went with the "multiple cable types, identical connectors" option, which is cheap but extremely confusing. The "multiple cable types, multiple connectors" is what USB was created to avoid. So the only remaining option to remove confusion is to have expensive cables.

by cletus 5y ago

danhor 5y ago

The Apple Thunderbolt 3 Pro Cable (2 m) is one of the only cables that can support everything usb-c over such a long distance [1]. But that costs 129$, which just wouldn't work for smartphone charging for which cables (usb-c 2.0 & 60w, the least you can do while still being spec-compliant) cost 7$. I think I haven't seen such a clear & easy to grasp demonstration of tradeoffs anywhere else. [1] For the longest time, this was the only cable to do it all. I think more are available now, but they're still very much non-affordable.

SAI_Peregrinus 5y ago

No, it's a matter of expense. It's possible to embed a redriver in the cable every 0.5m, and thus get longer cables at full speed. They're just very, very expensive. There are three alternatives: one cable type that does everything and is easy to use (but gets expensive quickly as it gets longer), multiple cable types that each do somewhat different things but use identical connectors, or multiple cable types that each do somewhat different things and use different connectors. The USB-IF went with the "multiple cable types, identical connectors" option, which is cheap but extremely confusing. The "multiple cable types, multiple connectors" is what USB was created to avoid. So the only remaining option to remove confusion is to have expensive cables.