[Starlink] Starlink power use & satellite tracking

[Ulrich Speidel]

I'd expect higher saturation to be associated with the use of fewer 
satellites per user terminal, and therefore lower power use.

Similarly, I'd expect proximity to gateways to be associated with higher 
power use.

What leads me to this impression?

Essentially, inter-satellite linking isn't yet in widespread use for 
Starlink, so most users at this point still use a bent-pipe arrangement 
terminal<->satellite<->gateway<->Internet.

This requires the satellite to be in view of both terminal and gateway. 
There is, however, no reason why a user's packets could not travel via a 
diversity of satellites. The only requirement for this arrangement is 
that the satellites used must be in the intersection of the set of 
satellites that the terminal can see and the set of satellites that the 
gateway can see.

What makes me think that this is actually happening? I'm in a low 
saturation cell close to multiple gateways and partial obstruction of 
the southern sky (which dishy uses in the southern hemisphere). So 
whatever satellite my dishy sees, the gateways also see (more or less), 
but the number of satellites I see is constrained by the partial 
obstruction, so jumps up and down over short periods of time as the 
satellites move in and out of view for me.

When I look at achievable rates with the likes of speedtest.net then I 
see huge jumps over relatively short periods of time. 20-30 Mb/s down 
one moment, 160+ Mb/s in the next run. This is exactly what I'd expect 
if dishy moves from a set of satellites with plenty of competition from 
neighbouring rural regions (e.g., satellites south-east of Auckland) to 
a larger set predominantly over the Tasman Sea, where there are no 
users. I'm simplifying here.

So if you happen to be a nerd in a fibre-connected and -penetrated city 
surrounded by gateways, you should see higher power use as Starlink 
wants you to have the maximum rate possible and will let you access 
whichever birds are available during the current time period. If you're 
in the wap-waps with your nearest gateway 100's of kilometres away (or 
miles for youse Americans and Brits, we're talking ballpark here ;-)), 
then the number of satellites you see that can relay to gateways for you 
should be smaller on average. You would be facing stiff competition for 
their capacity from your neighbours down the road. That would give you 
less chance to transmit, and hence lower power use. Note: A mitigating 
factor here could also be that the beams you need to communicate with 
these relaying satellites from your dishy might be further off bore than 
in the former case, which would require a little extra power to make up 
for longer path and lower dishy aperture.

Hope that makes sense?

On 18/02/2023 4:43 am, Michael Richardson wrote:
>
> Ulrich Speidel via Starlink <starlink at lists.bufferbloat.net> wrote:
> > * Whether you consider your cell Starlink virgin territory or close to
> > subscriber saturation (https://www.starlink.com/map 
> <https://www.starlink.com/map> 
> might help
> > determine that - if it's light blue, it's likely the former, if it's
> > "waitlist" blue but surrounded by light blue areas, or rural and
>
> What's the expected corrolation?
> Higher saturation => higher current? Or the opposite?
>
-- 
****************************************************************
Dr. Ulrich Speidel

School of Computer Science

Room 303S.594 (City Campus)

The University of Auckland
u.speidel at auckland.ac.nz  
http://www.cs.auckland.ac.nz/~ulrich/
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