4 ms·
starlink latency could be faster than shortwave, once full gen2 constellation launches, and if starlink decides to care about this industry. ...disclosure: i'm
by alexpil 6y ago
starlink latency could be faster than shortwave, once full gen2 constellation launches, and if starlink decides to care about this industry.
...disclosure: i'm the first one to build NY-Chi microwave, and Chi-Lon shortwave.
- modeless 6y agoCool! How do you figure? Doesn't shortwave take the great circle path, at lower altitude, making the path shorter?
- alexpil 6y agogen2 constellation is at 350km agl shortwave f-layer is at 200-400km agl depending on space weather difference is not that big
- modeless 6y agoSure, but it seems to me like the Starlink path will still be longer in almost all cases unless you're incredibly lucky and the satellites line up exactly along the path for a few seconds. And Starlink could have additional delays related to routing and possibly TDMA. What kind of latency issues need to be considered with shortwave?
- alexpil 6y agoa single orbital plane at 53' contains 7028 satellites (out of 40k total, but let's take one orbital plane) basic math, "satellite density" or "average distance between satellites" if they were just at random position is ~200km (napkin math, might be off).
- sargun 6y agoSome folks wrote a paper based on the proposed constellation: https://dl.acm.org/doi/10.1145/3286062.3286075 https://dl.acm.org/doi/10.1145/3286062.3286075 The paper actually talks about trading: > Already there are new private microwave relay links between New York and Chicago[11], London and Frankfurt[1], and London and Paris. These links have relatively low capacity compared to fiber, but are of high enough value to the finance industry to be worth building new low latency links In their paper, they say NYC / LON RTT will be between 58 and 66 ms -- this isn't much better than fiber. On the other hand, London to Joburg -- starlink has an advantage.
- sargun 6y agoIt's also bandwidth right? What's the throughput on shortwave? I believe that Starlink promises mbps+. I imagine there are applications you can implement on higher bandwidth are more interesting? Was Pilosoft always an HFT thing?
- alexpil 6y agohttps://visionscarto.net/enquete-reseaux-hft https://visionscarto.net/enquete-reseaux-hft and google translate for the backstory. bandwidth is a few bits per message, a few messages per second. yes you can do more with more bits and more messages, but you can do quite a lot with 2 bits!