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A classified network of SpaceX satellites is emitting a mysterious signal

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Re: A classified network of SpaceX satellites is emitting a mysterious signal

#41

Post by pavel_lishin »

Zigurd wrote: post #26
ACCount37 wrote: post #17

Earlier quoted context omitted.

The issue with terrestrial wireless links is that you just aren't going to cover every inch of Earth's surface with terrestrial wireless links. At the same time: coverage comes cheap to Starlink. Which makes it perfect for serving areas no one wants to serve. Such as rural areas, anything outside the largest cities in underdeveloped countries, the open ocean, and so it goes.

Places only Starllink can reach are an insufficient and shrinking TAM. The only places a terrestrial wireless provider doesn't want to serve are places that can't afford FWA even though it costs less.

> Places only Starllink can reach are an insufficient and shrinking TAM.

And yet, people live in those places, and you telling them that they're not economically worth serving isn't really solving their problem.

Re: A classified network of SpaceX satellites is emitting a mysterious signal

#42

Post by wongarsu »

Zigurd wrote: post #39
next_xibalba wrote: post #27

Earlier quoted context omitted.

Is there a viable alternative? SpaceX is the only launch provider and satellite operator that is progressing at a rapid pace and driving costs down.

2/3 of Falcon 9 launches are for Starlink. No outside revenue. SpaceX continues to require new investment rounds. So the whole "driving costs down" thing might only work until investors expect some actual free cash flow. There have been 11 test launches of starship. You might've missed the last one because it didn't do anything new, except shedding parts and exploding less. There's a pretty good chance that program w…

The last Starship launch was indeed unspectacular because it didn't try pushing the envelope particularly hard. The previous launches were much more precarious, with many fire balls. But I'm a strong believer in iterative development. It's bad PR when everyone can see every failed prototype, but the "design it once, simulate, and make sure the first prototype flies without issues" boxes you in to conservative design decisions.

Re: A classified network of SpaceX satellites is emitting a mysterious signal

#43

Post by lokar »

pavel_lishin wrote: post #41
Zigurd wrote: post #26

Earlier quoted context omitted.

Places only Starllink can reach are an insufficient and shrinking TAM. The only places a terrestrial wireless provider doesn't want to serve are places that can't afford FWA even though it costs less.

> Places only Starllink can reach are an insufficient and shrinking TAM. And yet, people live in those places, and you telling them that they're not economically worth serving isn't really solving their problem.

Pretending that they are worth economically serving with current tech or even tech that could be available soon does not help them either.

Re: A classified network of SpaceX satellites is emitting a mysterious signal

#44

Post by ajross »

iamnothere wrote: post #25
ajross wrote: post #22

Earlier quoted context omitted.

I really think point 1 needs an example. Again, older satellites talk to dishes, not random off-axis antennas hundreds of miles away. > Erosion of norms has real consequences when you are dealing with a scarce resource like RF spectrum. So... no, that's wrong. Like 99% of all wireless data transferred anywhere is squeezed into a paltry 100 MHz in the 2.4 GHz ISM band, with no effective guardrails of any kind about wh…

> dedicated bands have little to no value anymore Citation needed. Cellular devices are an obvious application that needs dedicated spectrum allocation. Amateur bands (including volunteer civil defense helpers) and private terrestrial radio systems count on their spectrum being clean enough for use. Emergency responders have critical radio systems with dedicated frequencies. Ships and airplanes use dedicated spectrum…

> Cellular devices are an obvious application that needs dedicated spectrum allocation.

Not since the death of TDMA, it isn't. Mobile bands are regulated to be exclusive, but nothing about LTE or 5G requires exclusive access or the absence of interference. These devices step on each others toes all the time and (via the magic of OFDMA and other dark trickery) still receive their data just fine.

You could start up a transmitter right in the middle of Verizon's or TMO's exclusive band (ICE is doing so all the time at protest sites across the country!) and the phones wouldn't bat a proverbial eyelash.

Re: A classified network of SpaceX satellites is emitting a mysterious signal

#45

Post by pavel_lishin »

lokar wrote: post #43
pavel_lishin wrote: post #41

Earlier quoted context omitted.

> Places only Starllink can reach are an insufficient and shrinking TAM. And yet, people live in those places, and you telling them that they're not economically worth serving isn't really solving their problem.

Pretending that they are worth economically serving with current tech or even tech that could be available soon does not help them either.

Who's pretending? If they're getting internet through Starlink, it sure sounds like they're being served.

Re: A classified network of SpaceX satellites is emitting a mysterious signal

#46

Post by __alexs »

BobbyTables2 wrote: post #12
Weeenion wrote: post #10

I'm curious if you could destroy a SpaceX Satelite with a basic laser pointers. Easily enough for normal state actors and some university or engineering lab. You need only to track it and shoot your laser up there (its only 500km) and if it can't dissipate the energy fast enough, it would overheat.

Try destroying a can of soda with a laser pointer first…

Not too hard https://www.youtube.com/watch?v=UBVlL0FNbSE

Re: A classified network of SpaceX satellites is emitting a mysterious signal

#47

Post by kragen »

ajross wrote: post #13

I'm all for a good spy story, but this seems like a big shrug to me. Interference-sensitive satellite communication is done with directional dishes, who cares what some other satellite is transmitting? That's the kind of nonsense you already engineered around. And of course all communication managed by modern ICs is done with some kind of spread spectrum protocol with the property that "interference" is a routine/exp…

This is not correct. Low-data-rate satellite communication is generally received on the satellite with omnidirectional antennas, because if you try to do it with directional dishes, any problem with your satellite's attitude control system or position estimation leaves you with a dead satellite, because the directional dish on the satellite is pointed somewhere you don't have a transmitting antenna. Attitude control problems can be serious in any case (for a publicly known example, see Kepler), but if you can't communicate with the satellite you have no chance to fix or work around the problem, or even find out what it was so the next satellite doesn't have it.

Re: A classified network of SpaceX satellites is emitting a mysterious signal

#48

Post by wildzzz »

Zigurd wrote: post #39
next_xibalba wrote: post #27

Earlier quoted context omitted.

Is there a viable alternative? SpaceX is the only launch provider and satellite operator that is progressing at a rapid pace and driving costs down.

2/3 of Falcon 9 launches are for Starlink. No outside revenue. SpaceX continues to require new investment rounds. So the whole "driving costs down" thing might only work until investors expect some actual free cash flow. There have been 11 test launches of starship. You might've missed the last one because it didn't do anything new, except shedding parts and exploding less. There's a pretty good chance that program w…

If SpaceX only had contract money as revenue, they'd be fine but they probably would not be innovating as fast. The investment rounds are to pay for Starlink build-out and Starship.

Re: A classified network of SpaceX satellites is emitting a mysterious signal

#49

Post by iamnothere »

ajross wrote: post #44
iamnothere wrote: post #25

Earlier quoted context omitted.

> dedicated bands have little to no value anymore Citation needed. Cellular devices are an obvious application that needs dedicated spectrum allocation. Amateur bands (including volunteer civil defense helpers) and private terrestrial radio systems count on their spectrum being clean enough for use. Emergency responders have critical radio systems with dedicated frequencies. Ships and airplanes use dedicated spectrum…

> Cellular devices are an obvious application that needs dedicated spectrum allocation. Not since the death of TDMA, it isn't. Mobile bands are regulated to be exclusive, but nothing about LTE or 5G requires exclusive access or the absence of interference. These devices step on each others toes all the time and (via the magic of OFDMA and other dark trickery) still receive their data just fine. You could start up a t…

Without rules around spectrum usage or interference in place, you’re saying I could just set up my own 1 MW transmitter on the cellular bands and the phones would just continue working as if nothing was happening? Fantastic, let’s get rid of the rules then. I have been wanting to build a giant spark gap in my backyard, that would finally make it legal.

Re: A classified network of SpaceX satellites is emitting a mysterious signal

#50

Post by anonymousiam »

The S-band uplinks are not typically used during operations. They're mostly used during transfer orbit operations and initial testing, and in emergencies when something goes wrong with the normal comms (safe mode). The S-band antennas on the satellite are typically omnidirectional, so they'll hear anything strong enough to overcome the noise floor. Those comms can be encrypted or in the clear, depending upon the situation. The military satellites that I'm familiar with stop listening to the S-band uplink when their normal uplink is operational, so interference shouldn't be an issue during normal operations.

I'm not involved in this stuff anymore (now retired), but it's possible that the Starshield constellation supports transmitting on S-band (or L-Band) as a means to relay SGLS communications to satellites that are out-of-view. Having this capability would greatly benefit the workflow of transfer orbit operations and initial testing, by eliminating the constraint that the satellite must be in-view to communicate with it. It would also benefit anomaly resolution by allowing instant access to a malfunctioning spacecraft.

https://en.wikipedia.org/wiki/Satellite_Control_Network

https://www.orbitalfocus.uk/Frequencies/FrequenciesSGLS.php

https://www.af.mil/News/Article-Display/Article/473264/af-sp...

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