4 ms·

Edit: I re-read your comment and I think I see what you might have meant now. I think you were asking if there would be a solution for low speed devices to use

Edit: I re-read your comment and I think I see what you might have meant now. I think you were asking if there would be a solution for low speed devices to use this standard.

dragontamer 3y ago
I'm asking if the LEDs that support 9.6Gbps (what is that? A 1ns or faster LED?) even exist in any substantial way. Isn't that like, laser speeds? Not overhead LED speeds. And over the air? Not inside a fiber line? This is basically a 10Gbps standard for fiber lines except over the air. All those issues need to be solved without the guarantees or isolation that fiber optic lines provide. That's just transmit. Receive has to deal with the same issues, amplifiers and other electronics that move at the requested speeds.
- sudosysgen 3y ago
  Couldn't you just use a laser and a lens?
- deleted 3y ago
  [deleted]
- deleted 3y ago
  [deleted]
- Scene_Cast2 3y ago
  Could one PWM such a light to display high bit color content? By my estimates: to send 9.6Gbps, you need (at least) 9.6 GHz, and that's 160,000,000x faster than 60hz. log2(160 million) = 27.3 bits. I'm sure that this idea is more of a fun hackaday-style gimmick (i.e. not productionizable for various reasons), but would be fun to see.
- namibj 3y ago
  I don't think they use OOK aka PAM2. I expect something like baseband OFDM fed to the AM-only-capable LED. Nicely isolates narrow band noise. Then usual high order QAM in the subcarriers. 256QAM gives you 8bit per symbol. So it'd only require 125MHz of modulation bandwidth...
  - dragontamer 3y ago
    You mean 1.2Ghz of modulation bandwidth to reach 9.6Gbps with 256QAM. Is that a 400ps rise + 400ps fall time LED? Picoseconds? Or the use of like 8192QAM or something incredible?
    - namibj 3y ago
      I don't know, I was pointing out for the data rate that seems to be part of some COTS devices, not the data rate that you can negotiate with research lab hardware.
- addaon 3y ago
  Single quantum well LEDs are well-commercialized at 150 Mbps for MOST150 (that was intended to, running over POF, be cheaper than an ethernet PHY and copper); I'm not sure exactly where SQW LEDs drop off and laser diodes become the only option, but it's substantially faster than traditional LEDs.

Edit: I re-read your comment and I think I see what you might have meant now. I think you were asking if there would be a solution for low speed devices to use this standard.

dragontamer 3y ago

I'm asking if the LEDs that support 9.6Gbps (what is that? A 1ns or faster LED?) even exist in any substantial way. Isn't that like, laser speeds? Not overhead LED speeds. And over the air? Not inside a fiber line? This is basically a 10Gbps standard for fiber lines except over the air. All those issues need to be solved without the guarantees or isolation that fiber optic lines provide. That's just transmit. Receive has to deal with the same issues, amplifiers and other electronics that move at the requested speeds.

sudosysgen 3y ago
Couldn't you just use a laser and a lens?
deleted 3y ago
[deleted]
deleted 3y ago
[deleted]
Scene_Cast2 3y ago
Could one PWM such a light to display high bit color content? By my estimates: to send 9.6Gbps, you need (at least) 9.6 GHz, and that's 160,000,000x faster than 60hz. log2(160 million) = 27.3 bits. I'm sure that this idea is more of a fun hackaday-style gimmick (i.e. not productionizable for various reasons), but would be fun to see.
namibj 3y ago
I don't think they use OOK aka PAM2. I expect something like baseband OFDM fed to the AM-only-capable LED. Nicely isolates narrow band noise. Then usual high order QAM in the subcarriers. 256QAM gives you 8bit per symbol. So it'd only require 125MHz of modulation bandwidth...
- dragontamer 3y ago
  You mean 1.2Ghz of modulation bandwidth to reach 9.6Gbps with 256QAM. Is that a 400ps rise + 400ps fall time LED? Picoseconds? Or the use of like 8192QAM or something incredible?
  - namibj 3y ago
    I don't know, I was pointing out for the data rate that seems to be part of some COTS devices, not the data rate that you can negotiate with research lab hardware.
addaon 3y ago
Single quantum well LEDs are well-commercialized at 150 Mbps for MOST150 (that was intended to, running over POF, be cheaper than an ethernet PHY and copper); I'm not sure exactly where SQW LEDs drop off and laser diodes become the only option, but it's substantially faster than traditional LEDs.