4 ms·
How are they getting latency so low? I used satellite internet for a month back in 2009 and it was brutal. Minimum 500ms. Literally had to break my lease to
by futevolei 6y ago
How are they getting latency so low? I used satellite internet for a month back in 2009 and it was brutal. Minimum 500ms. Literally had to break my lease to move to another place that offered broadband so I could actually work. I see starlink satellites are orbiting much lower but that would seem to only account for maybe 25% (?) of the gap between 20ms and 500ms.
- sbeller 6y agoHow did you come to the estimate of 25%? Because that difference in distance is the actual reason. The geostationary satellites used for your internet in 2009 are at ~2.5 of the earth diameter above ground (35k km, ca 1.5 earth circumference), whereas the starlink satellites are near the atmosphere (less than driving distance SF to LA). And speed of light is rather slow in these dimensions already.
- futevolei 6y agoI misread a different article which said spacex originally planned to have these satellites orbit around 800mi and I mistook that as normal altitude.
- Dylan16807 6y agoThe analysis is basically the same for 800 miles. That's 5 milliseconds per leg. Geostationary is 22000 miles. Though if you got 25%... did you calculate 115 milliseconds of speedup? That's the speedup for one leg. A ping to a server has to travel that distance four times.
- lordcarnafex 6y agoIn this case its mostly the altitude. Old satellite internet talked to geostationary sats in orbit (out in space around 32000km), these are only around 500km, so the signal itself only has 1.5% the distance to travel. Just speed of light alone means your old signal took around 100ms to get to the sat, and 100ms back, new one is 1.5ms there and 1.5ms back.
- futevolei 6y agoWow, I didn’t realize how much lower these satellites are.
- roamingryan 6y agoIt is also worth noting that propagation velocity in glass fiber is about 60% slower than free space. Once the constellation is dense enough and OISLs are working, they'll be able to undercut fiber latency. That is, if they actually decide to route signals in a purely latency-optimized manner. I wouldn't be at all surprised to see some sort of tiered pricing related to latency and latency jitter. No doubt the scummy high frequency traders are already jockeying to get out in front of this change in the telecom industry.
- seiferteric 6y agoI think your number is wrong right? Fiber should be 60% OF the speed of light, not 60% slower, so like 180km/s instead of 300km/s.
- leetcrew 6y agosince we're being pedantic about fractions, I should point out that your figure for c is off by about three orders of magnitude.
- futevolei 6y agoWhat would be the use case for hft? I assume this would be slower than any existing microwave networks, or whatever is fastest right now. Cities that for whatever reason can’t be connected via microwave like nyc-London? I’m aware this possibly/probably reads like amateur hour to anyone actually in the hft biz...
- wmf 6y agoYes, routes like NYC-London or London-Johannesburg. http://web.archive.org/web/20200819084001/http://nrg.cs.ucl.ac.uk/mjh/starlink-draft.pdf http://web.archive.org/web/20200819084001/http://nrg.cs.ucl....