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'We've bought the wrong satellites': UK tech gamble baffles experts

theguardian.com

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Re: 'We've bought the wrong satellites': UK tech gamble baffles experts

#11

Post by toomuchtodo »

londons_explore wrote: post #9
Havoc wrote: post #5

>the very talented lobbyists at OneWeb have convinced the government that we can completely redesign some of the satellites to piggyback a navigation payload on it. I mean it's hard not to laugh. All the major GNSS are herculean focused efforts over decades and the UK leadership reckons a ducktape solution will do. They would be better off just negotiating (paying) access to military encryption on GPS and Galileo and…

I disagree. GNSS systems used to be very complex and hard to design. Times have changed though, and nearly all the components are off-the-shelf now. If you already have the capability to launch a satellite, adding GNSS capabilities is a small extra step of adding an atomic clock and an antenna. All the signal generation can be software defined. All the complexity can live in models on the ground. Sure, some of the 'h…

What would the difficulty level be of incorporating GNSS into SpaceX’s StarLink satellites?

Re: 'We've bought the wrong satellites': UK tech gamble baffles experts

#12

Post by londons_explore »

toomuchtodo wrote: post #11
londons_explore wrote: post #9

Earlier quoted context omitted.

I disagree. GNSS systems used to be very complex and hard to design. Times have changed though, and nearly all the components are off-the-shelf now. If you already have the capability to launch a satellite, adding GNSS capabilities is a small extra step of adding an atomic clock and an antenna. All the signal generation can be software defined. All the complexity can live in models on the ground. Sure, some of the 'h…

What would the difficulty level be of incorporating GNSS into SpaceX’s StarLink satellites?

Low... I wouldn't be super surprised to discover they already have capable hardware onboard. Although ground receivers would need to use different frequency ranges and therefore it would probably be a non-starter.

Re: 'We've bought the wrong satellites': UK tech gamble baffles experts

#13

Post by Havoc »

toomuchtodo wrote: post #11
londons_explore wrote: post #9

Earlier quoted context omitted.

I disagree. GNSS systems used to be very complex and hard to design. Times have changed though, and nearly all the components are off-the-shelf now. If you already have the capability to launch a satellite, adding GNSS capabilities is a small extra step of adding an atomic clock and an antenna. All the signal generation can be software defined. All the complexity can live in models on the ground. Sure, some of the 'h…

What would the difficulty level be of incorporating GNSS into SpaceX’s StarLink satellites?

Good point actually. That could be a nice value add

Re: 'We've bought the wrong satellites': UK tech gamble baffles experts

#14

Post by econcon »

h2odragon wrote: post #2

So the "trick" to location satellite systems is super accurate and stable atomic clocks. Each satellite basically pings a timestamp out and you derive your location from the difference in when you receive which ping from several satellites. So the issue would be "how much more expensive is it going to be to equip these satellites with those clocks?" There might well be enough other uses for accurate clocks on these t…

Isn't this what Google's Spanner does?

Re: 'We've bought the wrong satellites': UK tech gamble baffles experts

#15

Post by usrusr »

toomuchtodo wrote: post #11
londons_explore wrote: post #9

Earlier quoted context omitted.

I disagree. GNSS systems used to be very complex and hard to design. Times have changed though, and nearly all the components are off-the-shelf now. If you already have the capability to launch a satellite, adding GNSS capabilities is a small extra step of adding an atomic clock and an antenna. All the signal generation can be software defined. All the complexity can live in models on the ground. Sure, some of the 'h…

What would the difficulty level be of incorporating GNSS into SpaceX’s StarLink satellites?

All the active station keeping required for small satellites in low orbits makes me wonder how much precision would suffer. Perhaps doable but requiring so much constant self-calibration that quality breaks down in areas without a network of active reference base stations? It's difficult to guesstimate the impact with magnitudes so far outside human scale.

Re: 'We've bought the wrong satellites': UK tech gamble baffles experts

#16

Post by Dylan16807 »

Junk_Collector wrote: post #4
h2odragon wrote: post #2

So the "trick" to location satellite systems is super accurate and stable atomic clocks. Each satellite basically pings a timestamp out and you derive your location from the difference in when you receive which ping from several satellites. So the issue would be "how much more expensive is it going to be to equip these satellites with those clocks?" There might well be enough other uses for accurate clocks on these t…

These satellites are likely too small to support a proper positioning system. They would need the radio transmitters, power system, and clocks all redesigned at which point you have an entirely new satellite.

> power system

I see different size estimates for these satellites but none of them suggest it would be hard for them to spend 10 watts on an atomic clock and 50 watts on a constant transmission. Am I forgetting something?

> radio transmitter

You can't just slap on a significantly simpler antenna?

> clocks

I have no idea here.

Re: 'We've bought the wrong satellites': UK tech gamble baffles experts

#17

Post by rorykoehler »

Havoc wrote: post #10
londons_explore wrote: post #9

Earlier quoted context omitted.

I disagree. GNSS systems used to be very complex and hard to design. Times have changed though, and nearly all the components are off-the-shelf now. If you already have the capability to launch a satellite, adding GNSS capabilities is a small extra step of adding an atomic clock and an antenna. All the signal generation can be software defined. All the complexity can live in models on the ground. Sure, some of the 'h…

>small extra step of adding [...] an antenna That's where the ducktape comes in I guess? (Just kidding) I mean yeah GPS is ancient tech. But actually getting the required 24 or whatever satellites into orbit (or retrofitting) and getting the receiver tech into enough hands to get any kind of traction is still a sizable challenge.

Couldn't they pay SpaceX or a similar company to do it for them?
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