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#11
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SpaceX gets FCC approval to deploy thousands more internet satellites
JF Mezei wrote on Mon, 19 Nov 2018
02:49:18 -0500: On 2018-11-18 21:38, Jeff Findley wrote: The cargo version of BFS will have a large payload bay . ok, so there will be a cargo version. Wasn't aware of that. Had only seen the draw2ings for the cruise shop with hundred+ passengers to Mars. You are frequently 'not aware' of things. Just how did you think that "cruise shop [sic]" got to Mars if there was no tanker version to refuel it in Earth orbit so that it could make the trip? Actually I'm not sure that's still current information, either. Original plan was for three versions; a 'passenger' version, a 'cargo' version, and a tanker version. One of the three went away. I thought they combined the 'passenger' and 'cargo' versions into a single more versatile vehicle. the payload bay door(s) will open and the satellites will be released in sequence just like Iridium satellites are released from a Falcon 9 upper stage. So the payload bay will be fitted with the satellite release mechanism specific to those stalellites, right? Sort of like the Shuttle payload being fitted with multiple PAM launchers ? Which part of "just like a Falcon 9 upper stage" is it that you're having trouble wrapping your head around? I don't understand your point. Since it's a global satellite network, you put the ground terminals exactly where they're needed. In Canada, unlike the USA, the vast majority of the area where services are needed do not have any fibre ANYWHERE near, so you can't place the ground stations where they are needed and need to aggregate traffic to a satteline that is over a ground station. Huh? With 7500 or so birds in orbit, a lot of them are going to be visible at once from any given point, even though they're only 350 miles or so up. So to serve a town like Resolute Bay at 73° latitude, the satellite that passes overhead may have to pass the signals down to another and then another to reach one that is over a ground station. The thing is that ground station will end up service a verty large area of northern Canada and thus aggregate a lot fo traffic and this is where the uplink capacity matters. Yes, the 7500 orbiting satellites are nodes in a single large network. What's your point? These aren't really huge "ground stations". This issue isn't their size (although you want a huge antenna to paliate rain/snow fade effect on the uplink since that will affect a lot of users. Again, huh? Again, this is a global LEO satellite network. SpaceX could put their ground stations closest to where the major data sources are in order to minimize latency and dependence on the existing Internet backbones. Again, it has to do with spectrum/bandwidth available for the uplink between one ground station and the staellite currently passing over it and how many end users end up being connected to that ground station. With 7500 satellites in the constellation, how many are visible from a given ground station? Nothing says you have to use the one directly overhead. Consider an extreme example of SpaceX having 1 antenna over Musk's home as the single ground station for the world. All satellites will be connected and data will flow from the internet to musk's home , on the uplink to a satellite and then relayed from satellite to satellite until i reacches the satelite over Gabon where it pushes the data down to the home of someone in Gabon. This all works and looks great. The problem is that that one uplink over Musk's home will be limited in capacity by how much spectrum the ITU/FCC will have given it and the capacity of the satellite passing over Musk's house at anty point in time. If you want to serve the world from 1 ground station, you will need many many terabits/second capacity on that uplink, and need all your satellites to be able to process all of the world's data demands since anyone satellite eventually becomes the one passing over Musk's home and acts as the main relay to the ground for all of Starlink's end users. Poppycock! What do you think the bandwidth of the internet backbone is? Hint: The biggest pipes are around 100 Gbs, over an order of magnitude smaller than your figure. Most of it is even smaller than that. So, it comes down to determining how many ground stations you can have and how many are needed in order to provide the complete system with uplink cxapacity that matches the demand from end users. The more ground stations you have, the more caopaciuty you have and the better the service end users will have. But the more ground statiosn you have, the costlier your system becomes. And then you start dealing with national regulators. Selling service to a Canadian will require the service abide by CRTC rules, notably net neutrality. But if the groudn station is in the USA where the Internet no longer exists as a telecom service, then the "information service" rules (or lack thereof() will apply. You still seem confused about how networks work. Same with a user in Taiwan who might end upo using a ground station located in China with all of the Chinese firewalls in place. An end user won't 'use a ground station' unless they're talking to a business local to that ground station. Again, you have no idea what Starlink's pricing will be. If you think it will be radically lower than existing services you are mistaken. Especially since Musk has stated it needs to generate revenue to find BFR/BFS, and once they realise how much gorund infrastructure they will need to support users worldwide, you'll find the costs go way up. While they haven't established how they're going to charge, they have said that by the mid-2020's they expect to have 40 million users generating $30 billion in revenue. That provides a guestimate of what the 'average' user will pay and it's just not all that high. The price of the launch is one thing. But if you have demand for X capaxity, but your system only provides for half of that, then you price service high and/or impose usage limits or lower speeds to limit demand for capacity which you don't have. If you oversell the service (as Xplornet does), then you get a terrible image and people hate you. Costs and speeds are expected to be commensurate with current wired internet. reusability. Starlink will get those launches at cost too. They'll be far cheaper than launches for any other LEO network. Getting launches at cost doesn't matter. It's all book keeping. What matters how how much will be oeration costs, groudn station costs and how much revenues they will get. (and factor in need to lauhch X satellites per year to replace falling ones in the longer term) The satellites are good for around 5.5 years. It costs less than $40 thousand to launch a new one (plus the cost of hardware). I think you're handwaving problems into existence that don't exist. -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw |
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SpaceX gets FCC approval to deploy thousands more internetsatellites
On 18-11-19 13:53 , Jeff Findley wrote:
Starlink just has to price themselves enough below the existing providers to steal their customers. ... ... As for ground station costs, that's why SpaceX is looking to build many ground stations around the planet. This isn't at all like owning a few GEO comsats with very few dedicated (uplink) ground stations for each comsat. This is a network with almost 12,000 satellites talking to hundreds of ground stations located strategically around the planet to provide service to millions of customers. Only "hundreds" of ground stations? I would have guessed at least tens of thousands of ground stations. Or did you mean to write "hundreds of thousands"? Do we know if one Starlink satellite will be able to communicate at the same time with several ground stations? Perhaps using time-division multiplexing? I assumed that each satellite would be equivalent to a cellular-phone tower and would create a Starlink "cell" to serve multiple ground stations at the same time. -- Niklas Holsti Tidorum Ltd niklas holsti tidorum fi . @ . |
#13
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SpaceX gets FCC approval to deploy thousands more internet satellites
JF Mezei wrote on Mon, 19 Nov 2018
18:40:01 -0500: Number of ground stations needed is relative to how much capacity the uplink has, and how many end users will be connecting to the Internet via that ground station. That number is essentially zero. 'End users' each have their own 'user terminal' and are leaf nodes on the network. Once you have too many end-users connecting via that uplink, you start to have congestion and need to build a second ground station far enough away to allow re-use of spectrum with different satellites acting as links to the ground station as they pass over. The system will use highly directional phased array antennae for uplink/downlink. That means you won't see a lot of frequency contention. Having multiple satellites connecting to same ground station may not be as efficient as having only one connecting at a time. Having 1 large chunk of spectrum allows greater "compression" than splitting that spectrum in 2 and having 2 separate satellites talk to the ground station. Doing both will be more efficient. You'd hardly want to bottleneck all the traffic for Netflix, say, through a single uplink. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
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SpaceX gets FCC approval to deploy thousands more internet satellites
JF Mezei wrote on Tue, 20 Nov 2018
18:34:08 -0500: Video showing the updated Starlink config. https://www.youtube.com/watch?v=QEIUdMiColU The large constellation is at a 53° inclination so of no use service the Arctic. (from 550km altitude, footprint not that big). Note that in the full system there are satellites in polar orbits. There appears to be a small constallation with polar orbits. Whether they provide constant converage is not known. (the vodeo doesn't focus on it as it appear to be a small part of the constellation). The video doesn't talk about it because the video is largely talking about 'first phase', which is just the 7500 or so satellites in lower orbits. Why do you think they would bother to add polar satellites if they don't provide coverage? The "sales pitch" appears to be aimed at selling capacity between major cities (such as between London and Los Angeles) as opposed to connecting retail customers to the Internet. What 'sales pitch'? You mean the examples mentioned in the video? Latency may be low enough at one point in time, but consider the added lag while links are renegotiated between satellite leaving and satellite arriving, each with their own links to other satellites. Latency stays low. The renegotiation gaps may be acceptable for retail (as they are for mobile phones when in a car/train), but not sure good enough for commercial. Why would they be different? Also, fibre has far more capacity than a laser. Not only can fibre support simulteneous wavelengths, but there are a lot of strands in a trans-atlantic cable for instance Lasers are faster. It's possible the satellite lasers will have multiple wavelengths, but not likely to have multiple beams since aim would become difficult between constantly moving staellites. Did you watch your own cite? Rates of change are low. The current design can handle 50% of the entire backhaul load of the current internet and around 10% of the uplink load from even very dense target areas. (the north-south links between sateliotes in same orbital plane would be stable, but those east-west links between staellites in different orbital planes would need sophisticated tracking and have varying distances. It's not THAT sophisticated. Rate of change is slow. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
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SpaceX gets FCC approval to deploy thousands more internet satellites
JF Mezei wrote on Wed, 21 Nov 2018
12:32:28 -0500: On 2018-11-21 08:20, Jeff Findley wrote: The video isn't a sales pitch, it's made by an expert in the field of communications. So, you're drawing conclusions about how this will be sold without actually knowing who SpaceX will be marketing this to. The expert would be using examples that spaceX gave him, so it does givce an indication of where SpaceX thinks there is market. Bull****. Stop pulling things out of your ass. They're EXAMPLES, which are typically simplified from how the system will actually be used. Depends how they do the routing algorithm. A smart software developer knows that you don't have to run the routing algorithm for every single packet of data because the satellites move in *very* predictable ways over time Since the east-west lasers are directional, it takes time to re-aim the laser to point to a new satellite that has come into view. north-sour links are stable, but re-routing to the north south link while you wait for the lasers to point to new satellite will change latency, and once contact with new satteelte has been established, a new chage in route happens. And they're aimed by arthritic dwarves, so it takes a LONG time to reaim vice the few milliseconds that any sane system would take. Also, fibre has far more capacity than a laser. Not only can fibre support simulteneous wavelengths, but there are a lot of strands in a trans-atlantic cable for instance You're talking out of your ass again. Please pray tell, explain how SpaceX lasers could match/exceed the lasers used for fibre links. Do they use subspace and go faster thah light ? Light in fiber is much slower than light in vacuum. It is, in point of fact, almost a third slower. Now don't you feel stupid for getting all snarky? Pray tell how the magical SpaceX laser could provide the capacity that is given by a cable of say 32 strands, each capable of 4 wavelengths of 100GBPS each. Show me such a fiber. CABLE BUNDLES of fiber are capable of 100 Gbps (which is much slower than 100GBPS). The fact is that Starlink will likely be *faster* than fiber connections. This means that trading companies will be willing to dump money into this project so they can reap the benefits (this has been mentioned in other articles on Starlink because those are your biggest potential initial customers). It really depends on how many hops between satellites are needed to go from A to B. Suspect New York-London may not be competitive because of adjacency to trans-atlantic cables. But Chicago or Los Angeles to London might compete, assuming the frequecy route changes in the sky maintain jitter to a minimum. You need to stop going with what you 'suspect', because you are almost inadvertently wrong. High frequency traders will be beating down the doors of SpaceX to get in on the ground floor of Starlink for the very reasons Krugman states in his article above. And they'll have wads of cash in hand. Until the first thunderstorm over their offices where traders lose connection for a few minutes and lose millions of dollars. Uh, RF works fine through thunderstorms. That's why the user terminals use RF rather than lasers. There are good reasons "serious" satellite applications want large dishes. It's called "weather". Wrong. Yes, SpaceX needs to promote their plan and PR it to death with all soprts of fancy promises. But just like BFR/BFS, expect those plans to be quietly slaled back once the accountants starts to tell Musk the grandiose plan won't pay for itself. You're insane. -- "Ordinarily he is insane. But he has lucid moments when he is only stupid." -- Heinrich Heine |
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SpaceX gets FCC approval to deploy thousands more internet satellites
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SpaceX gets FCC approval to deploy thousands more internet satellites
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#18
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SpaceX gets FCC approval to deploy thousands more internet satellites
JF Mezei wrote on Fri, 23 Nov 2018
13:49:18 -0500: On 2018-11-22 00:38, Fred J. McCall wrote: Light in fiber is much slower than light in vacuum. It is, in point of fact, almost a third slower. Now don't you feel stupid for getting all snarky? Yet, whenever it hits a satellite, that light has to be received, converted to electricity. Not clear if light pulse is routed to the emittor to the next satellite, or if the satellite needs to receive full packet before routing it. Every hop introduces latency, and that latency is greater when you route/switch packets instead of light pulses. So it bcomes very architecture dependant. (consider care of a light beam from A to B may contain packets destined to C or D, at whioch point you need packet switching). And more importantly, while your light may travel faster in vacuum, if it is a single beam, its capacity would be less and that too introduces latency as packets need to wait in a queue to get on the light beam. And if you use little gnomes living on each satellite to transcribe each packet on stone tablets, it will take even longer. Note that practically all the things you seem to think will slow down a laser link will also slow down a fiber link, except the speed of light in fiber is much slower. McCall doesn't believe 100gbps is common on fibre strands, doesn't believe that WDM exists to combine multiple separate 100gbps links on a single strand so hard to discuss when he is so focused on perosnal insults. Mayfly can't read simple declarative English, so it's hard to discuss anything when he is so focused on whinging. And am curious how SpaceX will deal with something called the "SUN". Sun hitting a sensor on a satellite may blind it from the much weaker laser signal coming from another satellite. Shades woudl be an obvious solutions if they can move quickly enough, but may not solve all cases such as when the sun is low and "parralel" to a laser beam from another satellite. I'm not curious at all, since I'm aware that laser light 'looks' very different from sunlight to a sensor. Show me such a fiber. CABLE BUNDLES of fiber are capable of 100 Gbps (which is much slower than 100GBPS). please use Google. The world has moved a lot since the days of 300 baud dialup with accoustic couplers. (and google "WDM fibre" Please support your own claims. That's your job, not mine. Uh, RF works fine through thunderstorms. That's why the user terminals use RF rather than lasers. "rain fade" for satellites or even microwave links (this is a major reason microwave links were not upgraded to modern speeds as rain fade would require the towers be rebuilt closer to each other). There are lots of relatively easy ways to deal with this 'problem'. If there weren't satellite radio and TV would stop working every time it rained. Hint: They don't. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
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SpaceX gets FCC approval to deploy thousands more internet satellites
JF Mezei wrote on Fri, 23 Nov 2018
23:28:44 -0500: On 2018-11-23 14:43, Jeff Findley wrote: You're assuming the lasers are the bottleneck. On what basis are you making this assumption? If satellites A B and C feed data to D who must then forward the data to E, then the D to E link will be 3 times oversubscribed if the first 3 links are at capacity. So if the network is badly designed by a moron there will be problems. Well, DOH! The solution, of course, is to not have a moron design it. Again, if they have single wavelength in the laser, this is small amount of capacity by today's standards. But adequate for 50% of current global internet backhaul capacity. And you seem to think (or at least be basing your whinging upon) the idea that Starlink is intended to REPLACE existing fiber. It's not. You keep throwing up these hand-waved arguments like no one at SpaceX has ever thought of these things. And you keep assuming that because Musk tweets stuff while high on cannabis or other, it must mean that SpaceX has not only thought of potential problems but also solved them. And you keep saying moronic things, like the preceding. It's why you're more a source of laughter than of serious discussion. -- "Ignorance is preferable to error, and he is less remote from the truth who believes nothing than he who believes what is wrong." -- Thomas Jefferson |
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SpaceX gets FCC approval to deploy thousands more internet satellites
JF Mezei wrote on Fri, 23 Nov 2018
23:32:21 -0500: On 2018-11-23 19:11, Fred J. McCall wrote: I'm not curious at all, since I'm aware that laser light 'looks' very different from sunlight to a sensor. Which spectrum does a laser use that the sun doesn't emit? I see you don't understand how lasers work, either. You need to think about spot power of a monochromatic source. If both transmit "red" light, then the sensor wont see the alternating pulses from the other satellite because while the pulse is off, the sensor will still show 100% red light instead of 0 siunce the sun will saturate the sensor at 100% whether the other satellite's laser is pulsed "on" or "off". Again, if we let someone like you design something stupidly it will have problems. It's why they don't let people like you design such things. -- "Ignorance is preferable to error, and he is less remote from the truth who believes nothing than he who believes what is wrong." -- Thomas Jefferson |
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