British GPS system
Discussion
It seems that the politician's latest brainwave regarding going it alone with a GPS system after losing our place on Galileo thanks to Brexit is to buy in to the bankrupt OneWeb - the problem being they are totally the wrong type of satellite, and in the wrong orbit to boot 
If you want a GPS system, you buy GPS satellites not internet comms ones - bloody obvious to anyone except our politicians
https://www.theguardian.com/science/2020/jun/26/sa...
If you want a GPS system, you buy GPS satellites not internet comms ones - bloody obvious to anyone except our politicians
https://www.theguardian.com/science/2020/jun/26/sa...
Terminator X said:
How do countries not part of the EU deal with GPS? Just do that.
TX.
They don't get the secure encrypted high-accuracy services - only the 'owners' of a particular system get that. The UK would have had access to Galileo's secure services but Brexit put a stop to that TX.
MartG said:
Terminator X said:
How do countries not part of the EU deal with GPS? Just do that.
TX.
They don't get the secure encrypted high-accuracy services - only the 'owners' of a particular system get that. The UK would have had access to Galileo's secure services but Brexit put a stop to that TX.
There is considerable interest in building satellite navigation systems in low earth orbit, rather than medium earth orbit where GPS and Galileo reside.
The satellites are much closer to earth, so the received signal is dozens or hundreds of times stronger - allowing faster signal lock, higher precision and less susceptibility to interference, as well as a larger data payload (i.e. more correction or orbital data can be included in the navigation signal).
More satellites are needed for coverage, so the overall system has more redundancy.
The satellites can be simplified - you don't need multiple redundant ultra-precision atomic clocks - you can use a smaller number of atomic clocks and exchange time signals between multiple individual satellites, or even simply use a normal quartz clock, and attach a GPS receiver to sync it to the GPS satellites in higher orbit.
So, although you need many more satellites and they have a shorter usable lifetime, they individually cost a fraction of a MEO satellite, and the launch costs are tiny in comparison.
On top of that the low earth orbit brings additional signal advantages - the high ground speed of the rapid orbits avoids the problem of reflections (from buildings/high ground/etc) confusing GPS receivers, because the reflections change rapidly over a period of seconds as the satellite flies past, and can be easily identified as outliers.
It's a radical project, unlike the incumbents. It is therefore quite high risk, but the basic technology is similar, and the launches much simpler. It's not so much "wrong" as "not done before".
The satellites are much closer to earth, so the received signal is dozens or hundreds of times stronger - allowing faster signal lock, higher precision and less susceptibility to interference, as well as a larger data payload (i.e. more correction or orbital data can be included in the navigation signal).
More satellites are needed for coverage, so the overall system has more redundancy.
The satellites can be simplified - you don't need multiple redundant ultra-precision atomic clocks - you can use a smaller number of atomic clocks and exchange time signals between multiple individual satellites, or even simply use a normal quartz clock, and attach a GPS receiver to sync it to the GPS satellites in higher orbit.
So, although you need many more satellites and they have a shorter usable lifetime, they individually cost a fraction of a MEO satellite, and the launch costs are tiny in comparison.
On top of that the low earth orbit brings additional signal advantages - the high ground speed of the rapid orbits avoids the problem of reflections (from buildings/high ground/etc) confusing GPS receivers, because the reflections change rapidly over a period of seconds as the satellite flies past, and can be easily identified as outliers.
It's a radical project, unlike the incumbents. It is therefore quite high risk, but the basic technology is similar, and the launches much simpler. It's not so much "wrong" as "not done before".
Galileo & the EU in particular can all go swivel as far as I'm concerned. It was always a "me too" boondoggle project from an organisation with delusions of grandeur. Pulling out of the Galileo project after they started dicking us around was the only thing I can think of that Theresa May ever got right in her entire sorry career. Well other than resigning, obviously.
A low Earth orbit GPS system sounds interesting. If, as seems to be the proposal, some of the OneWeb satellites can be repurposed into this role, then it makes more sense from a British point of view. The plan for the initial 648 OneWeb constellation would be dropped, and they'd keep about 80 of them for the GPS role. There are 68 operational ones up there currently.
A low Earth orbit GPS system sounds interesting. If, as seems to be the proposal, some of the OneWeb satellites can be repurposed into this role, then it makes more sense from a British point of view. The plan for the initial 648 OneWeb constellation would be dropped, and they'd keep about 80 of them for the GPS role. There are 68 operational ones up there currently.
Terminator X said:
How do countries not part of the EU deal with GPS? Just do that.
TX.
GPS is American, Glonass is Russian, Galileo is European, and there's a Chinese system as well. America, Russia (and I think Europe) let anyone use the low accuracy data but can turn it off any time they want. European partners in Galileo should always be able to get the high precision data. So lots of countries just use the lower accuracy GPS and Glonass data. TX.
As an allied nation, the UK military has access to the stronger and more accurate GPS P-code (Precise Code) signal anyway. Same goes for the even more accurate M-code (military code) as that comes online with the new gen of satellites they're putting up now.
As for Galileo, it's the encrypted, stronger and jam resistant PRS (Public Regulated Service) signal that the UK is blocked from. It's not a fully operational network yet anyway.
As for Galileo, it's the encrypted, stronger and jam resistant PRS (Public Regulated Service) signal that the UK is blocked from. It's not a fully operational network yet anyway.
WatchfulEye said:
There is considerable interest in building satellite navigation systems in low earth orbit, rather than medium earth orbit where GPS and Galileo reside.
The satellites are much closer to earth, so the received signal is dozens or hundreds of times stronger - allowing faster signal lock, higher precision and less susceptibility to interference, as well as a larger data payload (i.e. more correction or orbital data can be included in the navigation signal).
More satellites are needed for coverage, so the overall system has more redundancy.
The satellites can be simplified - you don't need multiple redundant ultra-precision atomic clocks - you can use a smaller number of atomic clocks and exchange time signals between multiple individual satellites, or even simply use a normal quartz clock, and attach a GPS receiver to sync it to the GPS satellites in higher orbit.
So, although you need many more satellites and they have a shorter usable lifetime, they individually cost a fraction of a MEO satellite, and the launch costs are tiny in comparison.
On top of that the low earth orbit brings additional signal advantages - the high ground speed of the rapid orbits avoids the problem of reflections (from buildings/high ground/etc) confusing GPS receivers, because the reflections change rapidly over a period of seconds as the satellite flies past, and can be easily identified as outliers.
It's a radical project, unlike the incumbents. It is therefore quite high risk, but the basic technology is similar, and the launches much simpler. It's not so much "wrong" as "not done before".
Interesting post thanks.The satellites are much closer to earth, so the received signal is dozens or hundreds of times stronger - allowing faster signal lock, higher precision and less susceptibility to interference, as well as a larger data payload (i.e. more correction or orbital data can be included in the navigation signal).
More satellites are needed for coverage, so the overall system has more redundancy.
The satellites can be simplified - you don't need multiple redundant ultra-precision atomic clocks - you can use a smaller number of atomic clocks and exchange time signals between multiple individual satellites, or even simply use a normal quartz clock, and attach a GPS receiver to sync it to the GPS satellites in higher orbit.
So, although you need many more satellites and they have a shorter usable lifetime, they individually cost a fraction of a MEO satellite, and the launch costs are tiny in comparison.
On top of that the low earth orbit brings additional signal advantages - the high ground speed of the rapid orbits avoids the problem of reflections (from buildings/high ground/etc) confusing GPS receivers, because the reflections change rapidly over a period of seconds as the satellite flies past, and can be easily identified as outliers.
It's a radical project, unlike the incumbents. It is therefore quite high risk, but the basic technology is similar, and the launches much simpler. It's not so much "wrong" as "not done before".
I guess the UK couldn't/shouldn't do this alone; are other countries interested in doing it or are doing it do you know?
As someone above said the EU doing Galileo is "me too", it is more exciting to do something different.
MartG said:
Terminator X said:
How do countries not part of the EU deal with GPS? Just do that.
TX.
They don't get the secure encrypted high-accuracy services - only the 'owners' of a particular system get that. The UK would have had access to Galileo's secure services but Brexit put a stop to that TX.
I am surprised that as a nation that has put in to fund the European version we’re currently not going to be entitled to access to it.
DeejRC said:
Amusingly the article is inaccurate in almost every aspect.
A large part of my Sunday will be working on the system non compliances.
It was the Guardian and aimed to stoke up the remainers who still want to moan on and on !A large part of my Sunday will be working on the system non compliances.
But it's an interesting thread though to see what the impact will be of Brexit and what the alternatives are. Maybe the simple answer is we save a load of money on a vanity project with no downside? Or maybe there will be major repercussions. Anyone know the facts?
The Oneweb satellites are quite small. The Galileo navigational payloads are relatively big, about twice the size of a Oneweb satellite. Ok, the Galileo design is getting on a bit now but I can't see it having been miniturised.
This isn't simply a case of slapping a few extra boxes of electronic gizmos on the existing satellite designs. This will require a complete new satellite design.
Space inside satellites tends to be at a premium. You need to mount the equipment on the body panels to keep the effects of the vibration environment during launch to a minimum. Mounting things on tall brackets is a bit of a no no, it amplifies the random vibration levels. Units that dissipate lots of heat need mounting on the panels. There are ways around the heat issue for units that dissipate less heat but it involves more mass. So we have an accommodation issue.
More mass from the extra payload. You need to see if the structure is up to it. The panels may need beefing up, thicker skins, denser honeycomb core. More mass. I will explain my mass fixation later.
Even if there were space, you need to get the power from somewhere. The solar panels would have been optimised in their size selection, excess capacity means having panels that are too big panel and is excess mass.
You will need to get rid of the extra power dissipated from the extra nav payload as well. For this you need extra panel area to radiate the heat away. You might get away with less powerful amplifiers for the inter satellite links & satellite/ground links as being LEO with more satellites the distances are smaller. You will also probably want doublers and heatpipes to move the heat around. More Mass!
The On Board Data Handling System will need a redesign to take the extra telecommands/telemetry. New TT&C units and a new wiring loom design. The ground segment will need a bit of a rework in this respect too.
Having now created a satellite, say, 25% heavier we need to look at how it is mounted on the launch vehicle. Can the satellite launch racking structure support the extra mass on launch? Again it will have been optimised, (I've reviewed enough stress analysis to know the margins involved), so probably a new one of those as well. Also, now less satellites on one launch, more launches = more cost.
This is not an "off the shelf solution". No Satellite project I worked on in 18 years as a spacecraft systems engineer was ever over endowed with excess power, and on occasion getting rid of the waste heat was a bit tight. Mass was always an issue (always my fault as well, although I simply compiled the mass budget from data given to me). Oneweb isn't the simple solution its being sold as as far as I can see.
I have seen too many projects try to go for the cheap option and end up being well over budget and schedule. I don't see this being different. Maybe I'm wrong, the only details I have on Oneweb are based on a quick trawl of the internet.
We have the ability to do such a project in the UK, we build the Galileo payloads, but it won't be cheap. There has been damage to the UK space industry due to Brexit and this will continue. Doing the project in the UK could be the uplift this part of UK industry needs.
This isn't simply a case of slapping a few extra boxes of electronic gizmos on the existing satellite designs. This will require a complete new satellite design.
Space inside satellites tends to be at a premium. You need to mount the equipment on the body panels to keep the effects of the vibration environment during launch to a minimum. Mounting things on tall brackets is a bit of a no no, it amplifies the random vibration levels. Units that dissipate lots of heat need mounting on the panels. There are ways around the heat issue for units that dissipate less heat but it involves more mass. So we have an accommodation issue.
More mass from the extra payload. You need to see if the structure is up to it. The panels may need beefing up, thicker skins, denser honeycomb core. More mass. I will explain my mass fixation later.
Even if there were space, you need to get the power from somewhere. The solar panels would have been optimised in their size selection, excess capacity means having panels that are too big panel and is excess mass.
You will need to get rid of the extra power dissipated from the extra nav payload as well. For this you need extra panel area to radiate the heat away. You might get away with less powerful amplifiers for the inter satellite links & satellite/ground links as being LEO with more satellites the distances are smaller. You will also probably want doublers and heatpipes to move the heat around. More Mass!
The On Board Data Handling System will need a redesign to take the extra telecommands/telemetry. New TT&C units and a new wiring loom design. The ground segment will need a bit of a rework in this respect too.
Having now created a satellite, say, 25% heavier we need to look at how it is mounted on the launch vehicle. Can the satellite launch racking structure support the extra mass on launch? Again it will have been optimised, (I've reviewed enough stress analysis to know the margins involved), so probably a new one of those as well. Also, now less satellites on one launch, more launches = more cost.
This is not an "off the shelf solution". No Satellite project I worked on in 18 years as a spacecraft systems engineer was ever over endowed with excess power, and on occasion getting rid of the waste heat was a bit tight. Mass was always an issue (always my fault as well, although I simply compiled the mass budget from data given to me). Oneweb isn't the simple solution its being sold as as far as I can see.
I have seen too many projects try to go for the cheap option and end up being well over budget and schedule. I don't see this being different. Maybe I'm wrong, the only details I have on Oneweb are based on a quick trawl of the internet.
We have the ability to do such a project in the UK, we build the Galileo payloads, but it won't be cheap. There has been damage to the UK space industry due to Brexit and this will continue. Doing the project in the UK could be the uplift this part of UK industry needs.
Brexit hasnt really damaged the UK space industry. In fact its currently (relatively) booming.The two main players we think of as "the Uk space industry" have taken major hits in the last few years but that has nothing to do with Brexit and everything to do with themselves. Amusingly UK companies are still in the prime seat for many of the Gal Transition contracts.
For what its work I can tell you the UK system is working to New Space rules.
You ex STV/PTH Tempest? Or the Guildford mob?
For what its work I can tell you the UK system is working to New Space rules.
You ex STV/PTH Tempest? Or the Guildford mob?
MikeStroud said:
DeejRC said:
Amusingly the article is inaccurate in almost every aspect.
A large part of my Sunday will be working on the system non compliances.
It was the Guardian and aimed to stoke up the remainers who still want to moan on and on !A large part of my Sunday will be working on the system non compliances.
But it's an interesting thread though to see what the impact will be of Brexit and what the alternatives are. Maybe the simple answer is we save a load of money on a vanity project with no downside? Or maybe there will be major repercussions. Anyone know the facts?
Re-launch the Black Arrow program https://en.wikipedia.org/wiki/Black_Arrow
Scrap our investment in the Eurofighter and resurrect the TSR2 program https://www.baesystems.com/en/heritage/bac-tsr-2
Ahhh..........those were the days poor money in to projects and scrap em
which every you look at Brexit we are well and truly F***'d
Well, well...
"A U.K. government consortium, led by an arm of Sunil Mittal's Bharti Enterprises Ltd., has won the bid for OneWeb, a bankrupt satellite firm whose investors include Japan’s SoftBank Group Corp.
Bharti Global Ltd. and the U.K. government will each commit $500 million in a deal expected to close by year end, the bidders said in emailed statements on Friday. Bharti will provide the company with “commercial and operational leadership” while the U.K. will have a final say over future access to the London-based satellite firm’s technology."
https://www.bloombergquint.com/business/sunil-mitt...
"A U.K. government consortium, led by an arm of Sunil Mittal's Bharti Enterprises Ltd., has won the bid for OneWeb, a bankrupt satellite firm whose investors include Japan’s SoftBank Group Corp.
Bharti Global Ltd. and the U.K. government will each commit $500 million in a deal expected to close by year end, the bidders said in emailed statements on Friday. Bharti will provide the company with “commercial and operational leadership” while the U.K. will have a final say over future access to the London-based satellite firm’s technology."
https://www.bloombergquint.com/business/sunil-mitt...
Edited by Beati Dogu on Friday 3rd July 14:49
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