starband has satellite for Wintel Boxes (M$ owns a part) Uplink power requirements are low because sent signal is GHz frequency (been in use a long time). Latency is time for signal to travel to satellite and bac (on the order of 1 second or less). Web pages and stuff with multiple links in one page need to be sent as one packet (like starband has been trying to do with its Mission Critcal software and proxy servers formats). 24 satellites are required for complete earth coverage (like GPS satellites). Main problem is slow upload speed <30 kps. Downloads ?20 to 60 kps on a good day with not many users.
<strong>starband has satellite for Wintel Boxes (M$ owns a part) Uplink power requirements are low because sent signal is GHz frequency (been in use a long time). Latency is time for signal to travel to satellite and bac (on the order of 1 second or less). Web pages and stuff with multiple links in one page need to be sent as one packet (like starband has been trying to do with its Mission Critcal software and proxy servers formats). 24 satellites are required for complete earth coverage (like GPS satellites). Main problem is slow upload speed <30 kps. Downloads ?20 to 60 kps on a good day with not many users.</strong><hr></blockquote>
You know this but not to confuse this for other users:
There is a HUGE difference between geo-stationary (hope it is the right word in english)
sattelites like GPS and "standart" communication sattelites and then the SkyCorp project.
For those who can´t get ADSL here in Denmark the sattelite internet access is, if not normal then not an unknown solution. The most used is one way (up via phone and down via sattelite).
Compared to "normal" sattelite systems SkyCorps cons are: Can´t function as a router, can´t use sattelites up there already and likely to be more expensive. Pros: Under optimal conditions you only need an Airport card not a sattlite dish.
<strong>starband has satellite for Wintel Boxes (M$ owns a part) Uplink power requirements are low because sent signal is GHz frequency (been in use a long time). Latency is time for signal to travel to satellite and bac (on the order of 1 second or less). Web pages and stuff with multiple links in one page need to be sent as one packet (like starband has been trying to do with its Mission Critcal software and proxy servers formats). 24 satellites are required for complete earth coverage (like GPS satellites). Main problem is slow upload speed <30 kps. Downloads ?20 to 60 kps on a good day with not many users.</strong><hr></blockquote>
As Anders says, You can't compare low earth orbit and geostationary systems. Geostationary satellites can use dishes, to give you a highly directional beam, as you know exactly where they are at all times, and so need a lot less power. The low earth orbit satellites move very fast across the sky, so you need to use a much less directional antenna (you could use a motorised dish and driver, but the cost would be excessive, and it would'nt be portable), and consequently more power. The difference in the antennae is at least as great at the other end, as well. There are also problems in reception from a moving target at high bandwidth because of changing delay causing phase distortion etc. etc. etc.
I found this via dejanews (google) and while some of the references are old (see Iridum) the explaination of the different types of orbit are very good... Pros and Cons are quite clear in the different types of orbit. It was written around Feb 2000.
Hope it helps...
[quote]When a satellite is launched, it may go into orbit at any height above the earth. There are generally 3 different classifications for satellite orbit heights, described below.
GEOS (Geosynchronous Earth Orbiting Satellite) - This type of orbit, also referred to as geostationary orbit, is when a satellite is launched to an altitude of precisely 22,300 miles above the Earth. At this altitude, the satellite orbits the Earth every 24 hours. Thus, to an observer stationed on the Earth, the satellite appears to be stationary. This is a tremendous advantage, as it allows complete 24 hour communication within its huge footprint (covering approximately 1/4 of the Earth). However, geosyncronous satellites are not ideal for voice circuit transmission. Due to their height above the it takes radio signals approximately .25 seconds to be transmitted to the satellite and reflected back down to Earth, depending on whether the signal is passed among satellites before it is transmitted back down to Earth. This delay is quite noticeable, and you may notice it when talking on international calls.
MEOS (Medium Earth Orbiting Satellite) - This type of orbit is within 6,000 - 12,000 miles above Earth. Approximately a dozen medium Earth orbiting satellites are necessary to provide continuous global coverage 24 hours a day. Several MEOS systems are now in development, most notably Bill Gates and Craig McCaw's Teledesic project, which will ultimately attempt to provide Internet access to all corners of the globe (all under Microsoft software, of course ).
LEOS (Low Earth Orbiting Satellite) - This type of orbit is generally within the 500 - 5,000 mile altitude range. Although the satellite footprint is greatly reduced, global coverage can be accomplished through a network of satellites, in which if an uplink is required to be transmitted to a location outside of the footprint, the transmission is passed from satellite to satellite until it reaches the satellite which has the location within its footprint. As there is no noticeable delay for signal transmission, low Earth orbiting satellites are becoming the preferable method of voice transmission, with numerous companies currently attempting to establish LEO satellite networks, most notably Motorola's Iridium project (see <a href="http://www.iridium.com)" target="_blank">www.iridium.com)</a>
<hr></blockquote>
The person who wrote it sure seems to know his/her stuff..
I don't see how the heck Airport technology (802.11-insert your favorite letter) could ever be used with any form of satellite based internet service.
Even in a LEOS orbit you are talking 500 MILES above the earth... Ever read any 'hack' to 802.11 that hits even one tenth that range? And the reason it can't is FCC rules and regs as well as the size of the frequency band...
Now is Apple re-using the word Airport to explain some other technology I dunno but Airport as in the "Apple AIrport Card" couldn't talk to even a LEOS.
Oh and even **IF** it could then why use the satellite at all... Just stick a super long range airport hub at IPS spaced every thousand miles or so apart all across the US... It would be a heck of a lot cheaper and easier than waiting on NASA to launch 500ish G4 Cubes into space.
In this case I'm sure that Apple is using the word Airport because it's easy and they don't have to get into a lot of techno speak trying to explain all this stuff.
Airport as we know it will NEVER transmit/recieve at a distance of 500 miles... Not in our lifetime. If they did you could kiss the land based cell based phone companies of the world goodbye not to mention the ISP and a ton of ther companies...
If you think that someone developing FREE ENERGY would have a huge impact on the world and cause millions and millions to loose their jobs then so would this...
The big difference is I have a feeling in this case it COULD be doable but the FCC and the other owners of the frequency bands would never let it happen...
Comments
<strong>starband has satellite for Wintel Boxes (M$ owns a part) Uplink power requirements are low because sent signal is GHz frequency (been in use a long time). Latency is time for signal to travel to satellite and bac (on the order of 1 second or less). Web pages and stuff with multiple links in one page need to be sent as one packet (like starband has been trying to do with its Mission Critcal software and proxy servers formats). 24 satellites are required for complete earth coverage (like GPS satellites). Main problem is slow upload speed <30 kps. Downloads ?20 to 60 kps on a good day with not many users.</strong><hr></blockquote>
You know this but not to confuse this for other users:
There is a HUGE difference between geo-stationary (hope it is the right word in english)
sattelites like GPS and "standart" communication sattelites and then the SkyCorp project.
For those who can´t get ADSL here in Denmark the sattelite internet access is, if not normal then not an unknown solution. The most used is one way (up via phone and down via sattelite).
Compared to "normal" sattelite systems SkyCorps cons are: Can´t function as a router, can´t use sattelites up there already and likely to be more expensive. Pros: Under optimal conditions you only need an Airport card not a sattlite dish.
__________________
[ 01-05-2002: Message edited by: Anders ]</p>
<strong>starband has satellite for Wintel Boxes (M$ owns a part) Uplink power requirements are low because sent signal is GHz frequency (been in use a long time). Latency is time for signal to travel to satellite and bac (on the order of 1 second or less). Web pages and stuff with multiple links in one page need to be sent as one packet (like starband has been trying to do with its Mission Critcal software and proxy servers formats). 24 satellites are required for complete earth coverage (like GPS satellites). Main problem is slow upload speed <30 kps. Downloads ?20 to 60 kps on a good day with not many users.</strong><hr></blockquote>
As Anders says, You can't compare low earth orbit and geostationary systems. Geostationary satellites can use dishes, to give you a highly directional beam, as you know exactly where they are at all times, and so need a lot less power. The low earth orbit satellites move very fast across the sky, so you need to use a much less directional antenna (you could use a motorised dish and driver, but the cost would be excessive, and it would'nt be portable), and consequently more power. The difference in the antennae is at least as great at the other end, as well. There are also problems in reception from a moving target at high bandwidth because of changing delay causing phase distortion etc. etc. etc.
Michael
__________________
[ 01-05-2002: Message edited by: Anders ]</p>
I found this via dejanews (google) and while some of the references are old (see Iridum) the explaination of the different types of orbit are very good... Pros and Cons are quite clear in the different types of orbit. It was written around Feb 2000.
Hope it helps...
[quote]When a satellite is launched, it may go into orbit at any height above the earth. There are generally 3 different classifications for satellite orbit heights, described below.
GEOS (Geosynchronous Earth Orbiting Satellite) - This type of orbit, also referred to as geostationary orbit, is when a satellite is launched to an altitude of precisely 22,300 miles above the Earth. At this altitude, the satellite orbits the Earth every 24 hours. Thus, to an observer stationed on the Earth, the satellite appears to be stationary. This is a tremendous advantage, as it allows complete 24 hour communication within its huge footprint (covering approximately 1/4 of the Earth). However, geosyncronous satellites are not ideal for voice circuit transmission. Due to their height above the it takes radio signals approximately .25 seconds to be transmitted to the satellite and reflected back down to Earth, depending on whether the signal is passed among satellites before it is transmitted back down to Earth. This delay is quite noticeable, and you may notice it when talking on international calls.
MEOS (Medium Earth Orbiting Satellite) - This type of orbit is within 6,000 - 12,000 miles above Earth. Approximately a dozen medium Earth orbiting satellites are necessary to provide continuous global coverage 24 hours a day. Several MEOS systems are now in development, most notably Bill Gates and Craig McCaw's Teledesic project, which will ultimately attempt to provide Internet access to all corners of the globe (all under Microsoft software, of course
LEOS (Low Earth Orbiting Satellite) - This type of orbit is generally within the 500 - 5,000 mile altitude range. Although the satellite footprint is greatly reduced, global coverage can be accomplished through a network of satellites, in which if an uplink is required to be transmitted to a location outside of the footprint, the transmission is passed from satellite to satellite until it reaches the satellite which has the location within its footprint. As there is no noticeable delay for signal transmission, low Earth orbiting satellites are becoming the preferable method of voice transmission, with numerous companies currently attempting to establish LEO satellite networks, most notably Motorola's Iridium project (see <a href="http://www.iridium.com)" target="_blank">www.iridium.com)</a>
<hr></blockquote>
The person who wrote it sure seems to know his/her stuff..
Dave
I don't see how the heck Airport technology (802.11-insert your favorite letter) could ever be used with any form of satellite based internet service.
Even in a LEOS orbit you are talking 500 MILES above the earth... Ever read any 'hack' to 802.11 that hits even one tenth that range? And the reason it can't is FCC rules and regs as well as the size of the frequency band...
Now is Apple re-using the word Airport to explain some other technology I dunno but Airport as in the "Apple AIrport Card" couldn't talk to even a LEOS.
Oh and even **IF** it could then why use the satellite at all... Just stick a super long range airport hub at IPS spaced every thousand miles or so apart all across the US... It would be a heck of a lot cheaper and easier than waiting on NASA to launch 500ish G4 Cubes into space.
In this case I'm sure that Apple is using the word Airport because it's easy and they don't have to get into a lot of techno speak trying to explain all this stuff.
Airport as we know it will NEVER transmit/recieve at a distance of 500 miles... Not in our lifetime. If they did you could kiss the land based cell based phone companies of the world goodbye not to mention the ISP and a ton of ther companies...
If you think that someone developing FREE ENERGY would have a huge impact on the world and cause millions and millions to loose their jobs then so would this...
The big difference is I have a feeling in this case it COULD be doable but the FCC and the other owners of the frequency bands would never let it happen...
Dave
[ 01-05-2002: Message edited by: DaveGee ]</p>