Wi-Wi is wireless time sync at 1 nanosecond

(jeffgeerling.com)

59 points | by Brajeshwar 2 days ago

3 comments

  • NkVczPkybiXICG 23 minutes ago
    Why does the title say 1ns but the body of the article says 30ns (with hopes to eventually get it down to 5)?
    • larpingscholar 0 minutes ago
      It's the period of the carrier wave (900MHz)?
  • ectospheno 2 days ago
    That is cool. I use a gps NTP server on my home network and live with sub-millisecond time sync. I’d go PTP but the equipment is a bit too expensive if the only value add is better time sync and I don’t need additional bandwidth. Prices coming down would be nice.
    • Youden 1 hour ago
      What's expensive? PTP is widely supported on commodity hardware these days. I think most Intel NICs support it, quite a few Realtek and a lot of embedded stuff, down to even MCUs like STM32.

      Even if you want a NIC with a stable oscillator or GPS inputs to act as a grandmaster, you can buy an E810 with the necessary hardware from eBay etc. for a few hundred or DIY something yourself much cheaper.

      • geerlingguy 24 minutes ago
        Switches that properly support PTP are expensive, at least for now.

        You can achieve microsecond accuracy with a lot of non-timing-specific networking hardware, but it's around as good as you get with modern NTP...

        To get sub-microsecond, you need hardware that supports transparent/boundary clock and doesn't just 'say' it does, but actually does (vendors have stamped PTP support on things that definitely don't account for time correctly internally!).

      • jcelerier 7 minutes ago
        out of dozens of laptops and computers we have where I work, we have maybe 3 that have a PTP-compatible NIC.
  • simulator5g 1 hour ago
    Better signal penetration with Wi-Wi could be a game changer for battery life.