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posted by martyb on Wednesday February 13 2019, @11:20AM   Printer-friendly
from the how-many-nanoseconds-is-50-meters? dept.

Cosemi Launches USB 3.1 Gen 2 Hybrid Active Optical Cable: Up to 50 Meters of USB

Cosemi has introduced the industry's first USB 3.1 Gen 2 hybrid active optical cables (hAOC), which enable USB connectivity over distances upwards of 50 meters. The cables will be available with various connectors and therefore will be able to address various applications.

As you might guess from the name, Cosemi's USB 3.1 Gen 2 hybrid active optical cables use fiber optics for data transfers, which is further paired with copper wires for control and power. The data portion of the cable is fully USB SuperSpeed+ capable, meaning it can transfer 10Gbps in each direction. [Notably], since hAOCs can power themselves, unlike other solutions they do not need any extension boxes or repeaters, making them simpler and more reliable. Using fiber for the data channel also means that the cables are more resistant against EM and RF interference, which is particularly important for medical applications.

The manufacturer plans to offer hAOCs with various types of connectors, including USB Type-A to USB Type-A, USB Type-A to USB Type-C, as well as USB Type-C to USB Type-C, with A-to-C cables being the first type out the door. And while the cables are best geared for high bandwidth applications, like copper USB 3.1 Gen 2 cables, the hybrid active optical cables are backwards compatible with the USB 2.0 spec.

I'd buy one for $5.


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  • (Score: 0) by Anonymous Coward on Wednesday February 13 2019, @12:24PM (12 children)

    by Anonymous Coward on Wednesday February 13 2019, @12:24PM (#800570)

    50.0 m/(299792458 m/s) = 167 nanoseconds. Probably a bit more than that but that's sort of the lower limit.

  • (Score: 5, Informative) by BsAtHome on Wednesday February 13 2019, @12:42PM (11 children)

    by BsAtHome (889) on Wednesday February 13 2019, @12:42PM (#800574)

    At a refractive index of ~1.5 it would be about 2e8 m/s (or about 250 ns for 50m). But you need to look at round-trip too. For optimal transfers, you will need some good windowed protocols.

    • (Score: 0) by Anonymous Coward on Wednesday February 13 2019, @02:59PM (10 children)

      by Anonymous Coward on Wednesday February 13 2019, @02:59PM (#800602)

      i can't believe that a serial connection is running over fiber. we've come a long way since rs-232 connectors were the common denominator across consumer platforms.

      • (Score: 2, Interesting) by Anonymous Coward on Wednesday February 13 2019, @03:23PM (9 children)

        by Anonymous Coward on Wednesday February 13 2019, @03:23PM (#800610)

        Cough, TOSLINK [wikipedia.org] 1983, cough, cough.

        • (Score: 2) by bzipitidoo on Wednesday February 13 2019, @04:06PM (8 children)

          by bzipitidoo (4388) on Wednesday February 13 2019, @04:06PM (#800617) Journal

          We've also taken big steps back. Twisted pair has been used for decades. Greatly increases the range by canceling out the interference that adjacent wires can produce in one another. It's why Ethernet can handle 100m, while USB can't swing more than a piddly 5m, if USB 2. (USB 3 is limited to just 3m.) But they wouldn't use twisted pair for USB. Costs a little more, so they wouldn't do it.

          • (Score: 0) by Anonymous Coward on Wednesday February 13 2019, @05:43PM (7 children)

            by Anonymous Coward on Wednesday February 13 2019, @05:43PM (#800663)

            USB specifications has mandatory differential twisted pair.
            Won't find many cables to use neither a twisted pair nor the mandatory wire gauge though.
            Then actual USB length problem most people have is due to the voltage drop.

            • (Score: 2) by bzipitidoo on Wednesday February 13 2019, @06:25PM (6 children)

              by bzipitidoo (4388) on Wednesday February 13 2019, @06:25PM (#800681) Journal

              Ah, my mistake. USB does indeed have twisted pair. It was the RS-232 serial port standard, with those ribbon cables, that was too cheap to use twisted pair.

              • (Score: 4, Informative) by pipedwho on Wednesday February 13 2019, @06:49PM (5 children)

                by pipedwho (2032) on Wednesday February 13 2019, @06:49PM (#800690)

                RS-422 and RS-485 were the balanced cable standards that made use of twisted pair. For low speed short range signalling between a terminal/computer and a modem, unbalanced signalling was fine and simplified the cabling that already needed to carry quite a few other ancillary signals like RTS/CTS/DTR/DSR/CD/RI/TX/RX/etc.

                • (Score: 2) by PartTimeZombie on Wednesday February 13 2019, @07:52PM (3 children)

                  by PartTimeZombie (4827) on Wednesday February 13 2019, @07:52PM (#800709)

                  Good lord you guys are nerds!

                  I mean that in the kindest way possible, in case you weren't sure. ;-)

                  • (Score: 2) by pipedwho on Wednesday February 13 2019, @09:42PM (2 children)

                    by pipedwho (2032) on Wednesday February 13 2019, @09:42PM (#800747)

                    I can’t believe I even remember this stuff!

                    • (Score: 2) by PartTimeZombie on Wednesday February 13 2019, @10:08PM (1 child)

                      by PartTimeZombie (4827) on Wednesday February 13 2019, @10:08PM (#800752)

                      I'm impressed.

                      • (Score: 0) by Anonymous Coward on Thursday February 14 2019, @10:51AM

                        by Anonymous Coward on Thursday February 14 2019, @10:51AM (#800948)

                        I am getting flashbacks of uni.
                        Thanks guys. I just had those years of my life nicely buried under layers of alcohol and work.

                • (Score: 2) by RS3 on Friday February 15 2019, @06:18AM

                  by RS3 (6367) on Friday February 15 2019, @06:18AM (#801438)

                  "Were"? They're still in use a lot. Besides industrial controls, RS-485 is used for stage lighting control, implemented as "DMX512" https://www.analog.com/en/analog-dialogue/articles/isolated-rs-485-in-dmx512-lighting.html [analog.com]. I might have guessed it could go 1000', but the Analog article says 4000' - pretty impressive.