@benjojo so I assume you’ve seen the boxes on aliexpress that do USB/HDMI/other stuff over fiber? There’s apparently a whole market for weird signals over optics! (and given price I am almost certain they are up to the very same shenanigans you are up to, using Ethernet optics to pull it off cheaply)

@benjojo @qwertyoruiop There's also the really crazy world of analog RF over fiber systems: https://longview.be/basic-rf-over-fiber-laser-driver.html

If you don't use SFP modules and instead drive the laser diode directly, they can transmit an enourmous bandwidth (up to several GHz) of analog signals.

Even more fun: The receivers can be passive, basically a tiny little solar cell, outputting enough RF energy to be picked up as RF signals by a regular receiver.

This is how coax television on GPON systems is sometimes done.

@benjojo @qwertyoruiop USB 3 is quite easy (though you’ll want a QSFP if you have 2xTx 2xRx lanes as per a fully specced USB-C port)

USB2 is a nightmare but ofc. specialised chips exist. Though surprisingly(?) USB2 has some obnoxious timeouts that mean you’ve gotta do some protocol-aware-MITM to extend it more than 100m or so

@benjojo @qwertyoruiop USB 3.0 (only, not 2.0) is also just LVDS. PCIe as well.

DisplayPort is a bit annoying because you need QSFP modules, but otherwise, yeah, lots of fun :3

@benjojo @qwertyoruiop I'm actually planning on building a DP over QSFP+ thingie ^^' (also IR from my smartmeter directly coupled into singlemode fiber is on my todo list)

@benjojo @qwertyoruiop I have wondered for a few years about whether it'd be possible to feed DisplayPort (and maybe also HDMI 2.1) in to a QSFP in a useful way, dedicated active optical cables are annoying to deal with so it'd be really neat to be able to just use generic fiber in effectively arbitrary lengths.

@benjojo There is also https://m.youtube.com/watch?v=1H4FuNAByUs -- but I guess I'm not the first to link it?

@benjojo I like how you expand TOSLINK as Toshiba Link but not S/PDIF as Sony/Philips Digital Interface

Too many companies involved here

@benjojo Reminds me of @marcan's experiments with TOSLINK over air.

@benjojo in school we had an exercise where we had "some loops" of fiber optic and send a laser in to measure its distance, total and where it was patched. Turn out that was 20km that did fit inside a pizza box.

Using real infrastructure is much more impressive :)

@benjojo just watched the talk, very fun :D For the truly biggest waste of bandwidth, I propose Morse over fiber.

@benjojo S/PDIF has hardware specs for optical and electrical physical layers, but now I'm wondering if the EME people could bounce an S/PDIF bitstream off the moon without too much round-trip distortion.

@benjojo saw the video of the talk last night, it was super fun, great job!

@benjojo so you've turned TOSLINK into a TOSser LINK?

-- but seriously, that's amazing!

(And forgive this USian's associations with British slang)

@benjojo i mean look how quickly the audio came back after you replugged that! no standard eth switch is getting close

@benjojo and thanks to you I have now a million more projects!

@benjojo That was a lot of fun! Some author needs to use this as a 'side' channel between data centers that isn't monitored 😉 for a plot device. Thanks for taking the time to write that up. 🙏

@benjojo this is soo cool

@benjojo
Honestly, while there isn't much need to do it with TOSLink, I can absolutely see someone wanting a 200km MADI run.

@benjojo Love the dig at LD5 😂

Also…

> Technically not inter-city as Slough is not a city but a town

And nor is (what people commonly call) London!

@benjojo Absolutely loved your blog post. Read it from start to finish, and enjoyed every part. This is the kind of stuff I love randomly finding on the internet.

@benjojo Sounds like a fun experiment!

I miss working out of Telehouse and Global Switch! The company I work for used to locate kit in both buildings but has long since pulled out of them :(

And my current office is only 2 buildings up from Equinix LD6 😂

@benjojo "I assume this would probably confuse an intelligence agency if they were tapping the line."

Well that's the best motivation.