[Starlink] Starlink Reverse Engineering

[Starlink] Starlink Reverse Engineering

[Hesham ElBakoury]

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This MIT Technology Review report provides the details of the work done by
Professor Humphrey and his team to reverse engineer starlink signals:
https://www.google.com/amp/s/www.technologyreview.com/2022/10/21/1062001/spacex-starlink-signals-reverse-engineered-gps/amp/

It is worth it to mention that Elon Musk does not like using starlink for
navigation which is the motivation behind Humphrey

Although the report mentions Humphrey non-peer reviewed paper, actually the
peer-reviewed paper has been published here

https://ieeexplore.ieee.org/abstract/document/10107477?casa_token=ws8yh0wRnRsAAAAhA:Q0LZ3Gt-vxKsGQ170OhIp4X4tQoa_U2m6DlBKY7a-A0EYxTzRd4VLzpHkZKSglEPiMEJKK4XTHk
<https://ieeexplore.ieee.org/abstract/document/10107477?casa_token=ws8yh0wRnRsAAAAA:Q0LZ3Gt-vxKsGQ170OhIp4X4tQoa_U2m6DlBKY7a-A0EYxTzRd4VLzpHkZKSglEPiMEJKK4XTHk>
Hesham

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Re: [Starlink] Starlink Reverse Engineering

[Larry Press]

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Why does Elon Musk object to the use of Starlink for navigation?

Get Outlook for Android<https://aka.ms/AAb9ysg>
________________________________
From: Starlink <starlink-bounces@lists.bufferbloat.net> on behalf of Hesham ElBakoury via Starlink <starlink@lists.bufferbloat.net>
Sent: Friday, September 8, 2023 5:27:22 PM
To: starlink@lists.bufferbloat.net <starlink@lists.bufferbloat.net>
Subject: [Starlink] Starlink Reverse Engineering

This MIT Technology Review report provides the details of the work done by Professor Humphrey and his team to reverse engineer starlink signals: https://www.google.com/amp/s/www.technologyreview.com/2022/10/21/1062001/spacex-starlink-signals-reverse-engineered-gps/amp/<https://urldefense.com/v3/__https://www.google.com/amp/s/www.technologyreview.com/2022/10/21/1062001/spacex-starlink-signals-reverse-engineered-gps/amp/__;!!P7nkOOY!uvKxQt1rcYRmzqkpdhQQiPVH9sJm19Cf-5iUpkIm4CqaB1VyomQeC4Sft16J9XFVTEvRugU8VOdCc58FEM1WD25_ZQ$>

It is worth it to mention that Elon Musk does not like using starlink for navigation which is the motivation behind Humphrey

Although the report mentions Humphrey non-peer reviewed paper, actually the peer-reviewed paper has been published here
 https://ieeexplore.ieee.org/abstract/document/10107477?casa_token=ws8yh0wRnRsAAAAhA:Q0LZ3Gt-vxKsGQ170OhIp4X4tQoa_U2m6DlBKY7a-A0EYxTzRd4VLzpHkZKSglEPiMEJKK4XTHk<https://urldefense.com/v3/__https://ieeexplore.ieee.org/abstract/document/10107477?casa_token=ws8yh0wRnRsAAAAA:Q0LZ3Gt-vxKsGQ170OhIp4X4tQoa_U2m6DlBKY7a-A0EYxTzRd4VLzpHkZKSglEPiMEJKK4XTHk__;!!P7nkOOY!uvKxQt1rcYRmzqkpdhQQiPVH9sJm19Cf-5iUpkIm4CqaB1VyomQeC4Sft16J9XFVTEvRugU8VOdCc58FEM0kG4phIg$>
Hesham

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Re: [Starlink] Starlink Reverse Engineering

[David Lang]

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On Sat, 9 Sep 2023, Larry Press via Starlink wrote:

> Why does Elon Musk object to the use of Starlink for navigation?

He hasn't said, but I suspect a couple reasons

limitations on what SpaceX can do, orbital changes, protocol changes, etc 
could all affect people depending on something that Starlink wasn't intending to 
offer in the first place

liability, what happens when the navigation gives the wrong location because 
of a change Starlink made.

to use the satellite signals, you not only need the timing, you need rather 
precise orbital information. If the satellites are modifying their orbits 
autonomously, how does that information get to everyone?

For normal Starlink purposes, the satellites determine which sat is covering 
what area on the ground and the ground stations can react to the different sats 
that they hear (beaming back on reciprical bearings or the beam info can be in 
the handshake)

but navigation requires getting the signals from many sats at once to work out 
the timing between them

note, I have no inside info, this is just my version of logical guessing.

David Lang


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Re: [Starlink] Starlink Reverse Engineering

[Hesham ElBakoury]

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This is what is in the MIT Technology Review report:
"*When the idea was first proposed in 2020
<https://www.technologyreview.com/2020/09/28/1008972/us-army-spacex-musk-starlink-satellites-gps-unjammable-navigation/>,
executives at SpaceX were open to the idea, says Humphreys. Then word came
from on high. “Elon told the leaders we spoke to: every other LEO [low
Earth orbit] communications network has gone into bankruptcy,” Humphreys
told MIT Technology Review. “And so we [SpaceX] have to focus completely on
staying out of bankruptcy. We cannot afford any distractions.*”

Heshamn

On Fri, Sep 8, 2023, 9:15 PM David Lang <david@lang.hm> wrote:

> On Sat, 9 Sep 2023, Larry Press via Starlink wrote:
>
> > Why does Elon Musk object to the use of Starlink for navigation?
>
> He hasn't said, but I suspect a couple reasons
>
> limitations on what SpaceX can do, orbital changes, protocol changes, etc
> could all affect people depending on something that Starlink wasn't
> intending to
> offer in the first place
>
> liability, what happens when the navigation gives the wrong location
> because
> of a change Starlink made.
>
> to use the satellite signals, you not only need the timing, you need
> rather
> precise orbital information. If the satellites are modifying their orbits
> autonomously, how does that information get to everyone?
>
> For normal Starlink purposes, the satellites determine which sat is
> covering
> what area on the ground and the ground stations can react to the different
> sats
> that they hear (beaming back on reciprical bearings or the beam info can
> be in
> the handshake)
>
> but navigation requires getting the signals from many sats at once to work
> out
> the timing between them
>
> note, I have no inside info, this is just my version of logical guessing.
>
> David Lang
>
> _______________________________________________
> Starlink mailing list
> Starlink@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/starlink
>

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Re: [Starlink] Starlink Reverse Engineering

[Alexandre Petrescu]

Le 08/09/2023 à 16:27, Hesham ElBakoury via Starlink a écrit :
> This MIT Technology Review report provides the details of the work 
> done by Professor Humphrey and his team to reverse engineer starlink 
> signals: 
> https://www.google.com/amp/s/www.technologyreview.com/2022/10/21/1062001/spacex-starlink-signals-reverse-engineered-gps/amp/

Thanks for the pointer.  I have not read it.

But, I would challenge the concept of reverse engineering there to say 
that one might not need to reverse engineer at very low level to achieve 
that effect.

In a WiFi and GSM setting (not starlink), people do not reverse engineer 
it too much to make localisation out of wifi beacons and GSM cell info.  
Just like starlink, WiFi and GSM were not designed to do localisation, 
yet the current smartphone localisation info ('where am I') is relying 
extensively on GSM, WiFi, bluetooth and other non GPS signals.  I 
suspect it relies on these even more than on signals that were designed 
to do localisation like the Galileo and other countries signals.

In the future, with this constant increase of starlink availability, it 
might be possible to add starlink as an additional source of time and 
localisation (in addition to GSM, WiFi etc) without any reverse 
engineering.  Just listen to the signals (if they are not crypted, I 
dont know) and derive some info from there.

The position of the starlink sats themselves is public info.  So, it is 
very possible to derive a more precise the position ('where am I') from 
the sats that I receive, and knowing which sats are currently in view at 
my approximate location.  Probably there are already some smartphone 
apps that show that somehow.

The interesting thing would be the other way around: non-starlink sats 
listen to starlink signals emitted by ground user antennas and tell 
where these users are.   Even that would not require very deep reverse 
engineering, but the achieved effect could be very effective.  Of 
course, it depends how it is used, for which purpose.

Alex

>
> It is worth it to mention that Elon Musk does not like using starlink 
> for navigation which is the motivation behind Humphrey
>
> Although the report mentions Humphrey non-peer reviewed paper, 
> actually the peer-reviewed paper has been published here
> https://ieeexplore.ieee.org/abstract/document/10107477?casa_token=ws8yh0wRnRsAAAAhA:Q0LZ3Gt-vxKsGQ170OhIp4X4tQoa_U2m6DlBKY7a-A0EYxTzRd4VLzpHkZKSglEPiMEJKK4XTHk 
> <https://ieeexplore.ieee.org/abstract/document/10107477?casa_token=ws8yh0wRnRsAAAAA:Q0LZ3Gt-vxKsGQ170OhIp4X4tQoa_U2m6DlBKY7a-A0EYxTzRd4VLzpHkZKSglEPiMEJKK4XTHk>
> Hesham
>
> _______________________________________________
> Starlink mailing list
> Starlink@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/starlink