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old.QorbeQ
Guest
I was on a CounterStrike server the other night and an American chap called "Whispering Death" was getting all excited because he was about to get 2Mbit/sec downloads via a satellite. Being a satcomms engineer working at a satellite communications station [ http://www.parallel.clara.co.uk/madley_1.jpg ] I figured that I'd explain things to him. A little awkward in the middle of a CounterStrike game and I never managed to fully explain things to him (especially the low-earth possibility below).... anyway ... just in case he happens by (and for anyone else contemplating the service...)
He was playing on a 300-ping (not unsurprisingly) and was all excited because he was expecting to ping in the 20-30ms range... which he may well NOT get at all...
What normally happens with satellite-based internet connections is that you have a ground-link based UPLINK to the net (cable modem, ISDN, telephone, whatever) and the DOWNLINK comes via the satellite so that you've got plenty of bandwidth.
Whilst this is undeniably FANTASTIC for email, surfing and general IRC idling, it's not much cop for playing games over.
Why? Well, for a normal satellite-internet solution you have a dish-based system using geostationary satellites (always in the same place above the Earth).
It is technically possible to use the low-earth-orbit comms systems that have been recently introduced (lots of satellites whizzing around the sky) but that is much more expensive so it would be unlikely that it was one of those.
So, assuming it's a system with a dish pointing at a geostationary satellite (likely) then the satellite is located 22,000 miles above the Earth. Yes, 22,000. A long way. (Technically it's not EXACTLY 22,000 miles but it's close enough...)
Speed of light? 186,000 miles a second. Time taken to travel 22,000 miles? (22,000 / 186,000 = 0.118). That's 118ms. And thats only one way. Back down from the satellite, another 118ms.
Total trip from the ISP to your computer? 236ms MINIMUM. (It's generally quoted in the business as a quarter of a second because it's around that - it's the "satellite delay" that you see on some international TV outside broadcasts).
This means that the total ping round-trip time for games will be whatever-your-ground-based-uplink ping is (20ms? 30ms?) plus the satellite delay (236ms) plus any associated delays through the satellite modems and/or demodems (say, 10ms being exttremely generous?)...
236+20+10 ... around 270ms (being generous) ... suffice to say not too good for gaming... don't do it expecting good gaming performance... great for web/email/etc... lots of bandwidth... pings like a dog...
Like I said, it is technically possible to use lots of low-earth-orbit satellites (300miles istr?) a'la those new mobile phones, but I'd find it unlikely that anyone is using those for large-scale satellite internet projects (yet, at least) because of the cost of using them...
He was playing on a 300-ping (not unsurprisingly) and was all excited because he was expecting to ping in the 20-30ms range... which he may well NOT get at all...
What normally happens with satellite-based internet connections is that you have a ground-link based UPLINK to the net (cable modem, ISDN, telephone, whatever) and the DOWNLINK comes via the satellite so that you've got plenty of bandwidth.
Whilst this is undeniably FANTASTIC for email, surfing and general IRC idling, it's not much cop for playing games over.
Why? Well, for a normal satellite-internet solution you have a dish-based system using geostationary satellites (always in the same place above the Earth).
It is technically possible to use the low-earth-orbit comms systems that have been recently introduced (lots of satellites whizzing around the sky) but that is much more expensive so it would be unlikely that it was one of those.
So, assuming it's a system with a dish pointing at a geostationary satellite (likely) then the satellite is located 22,000 miles above the Earth. Yes, 22,000. A long way. (Technically it's not EXACTLY 22,000 miles but it's close enough...)
Speed of light? 186,000 miles a second. Time taken to travel 22,000 miles? (22,000 / 186,000 = 0.118). That's 118ms. And thats only one way. Back down from the satellite, another 118ms.
Total trip from the ISP to your computer? 236ms MINIMUM. (It's generally quoted in the business as a quarter of a second because it's around that - it's the "satellite delay" that you see on some international TV outside broadcasts).
This means that the total ping round-trip time for games will be whatever-your-ground-based-uplink ping is (20ms? 30ms?) plus the satellite delay (236ms) plus any associated delays through the satellite modems and/or demodems (say, 10ms being exttremely generous?)...
236+20+10 ... around 270ms (being generous) ... suffice to say not too good for gaming... don't do it expecting good gaming performance... great for web/email/etc... lots of bandwidth... pings like a dog...
Like I said, it is technically possible to use lots of low-earth-orbit satellites (300miles istr?) a'la those new mobile phones, but I'd find it unlikely that anyone is using those for large-scale satellite internet projects (yet, at least) because of the cost of using them...