[Starlink] Speaking of retirements...

[Ulrich Speidel]

On 25/09/2023 11:32 pm, Noel Butler via Starlink wrote:
>
> On 25/09/2023 18:06, Alexandre Petrescu via Starlink wrote:
>
>> ah, sorry, probably we speak of the same thing.
>>
>> I dont know whether or not the current in-car starlink devices 
>> require an extra 12v-to-220V/110V adapter, or whether it's included, 
>> or integrated.
> Here, the  "RV" is identical to a household service, the same stuff, 
> except your allowed to move around - not locked to the beam covering 
> your home location.

Depending on where on the globe you live, there is a difference in the 
range of Dishy options available (or at least advertised), which is 
where perhaps some of the confusion arises.

The "RV" option available in Australia and NZ at this time is indeed the 
residential option without the cell lock. It's intended for stationary 
use and assumes that you have a mains (AC) power source. We've tried it 
here with the much taunted Yaosheng adapter, which however isn't 12V (it 
needs 42V) and which gave us a lot more outages than the Starlink router 
with Ethernet adapter.

There is also a "mobility" option available here (or at least they offer 
sales consultations for it) that's shown mounted flat on the roof of a 
speeding 4WD and seems to be quite different from a residential class 
Dishy. Presumably that will run off 12V. Cost is significantly more than 
for the RV option, and there's an "up to" caveat on the data rate, which 
I take to mean "I you decide to hoon around with a Dishy that doesn't 
really have the opportunity to track properly with its phased array, 
then expect to have to track multiple sats in parallel to stay 
connected, and expect to pay for the privilege of occupying a larger 
number of slots, many of which you won't get to use properly".

>>
>> These 12V-220V/110V adapters are relatively big, necessitate fans.
> If you're getting the "RV/camping/portable" equipment you'd want to 
> use your 12volt system that nearly all campers and RV's I've seen with 
> factory electrics come with (A couple RV models are 24v) so the DC 
> supply woud need to accept 12 to 48 input, slightly less heat is 
> generated if you use 24v and even less again if 48v since it only 
> bucks it for the 12v parts of the circuitry in modem. You would not 
> want to use an AC supply, defeats the purpose of the design of that 
> service, the 12 to 48v boost converters for the dish to work have 
> decent heat sinks, a little better ventilation in the modems for that 
> little bit of extra heat would be beneficial.
>> If they are still needed for starlink in-car devices is probably 
>> because of higher transmit power that is necessary to reach to 360km 
>> altitude. They could reduce that in-car power need by bringing the 
>> sats even lower, or other non-sat objects like HAPs.  Or by 
>> augmenting the starlink sat antennas sizes.
> They are identical hardware, no extra power is needed, since there is 
> 350  odd km's to the satellite, do you really think the 2 or so metres 
> AGL for campers, would really need more power compared to the standard 
> unit at 10 metres AGL, at say a house mounted dish :)  In early days I 
> remember  quite a few youtubers using the stand on the ground in their 
> back yard, and they probably still do.

Distance to the satellite is usually much more than 350 odd km. The vast 
majority of Starlink sats orbit at around 550 km, and your Dishy does 
not normally talk to satellites straight overhead (except in a few 
select latitudes, such as close to the 53rd parallels, where it may do 
so if there is one right overhead at the time). In moderate latitudes, 
where much of humanity lives, Dishy will point itself in the direction 
of the nearest 53rd parallel and track satellites it can see in roughly 
that direction, meaning that most satellites Dishy talks to are more 
like 800 - 1000 km away. Near the Equator, Dishy will remain in "coffee 
table" position but avoid the geostationary arc, which also means that 
the sats it talks to are quite a bit off to the side all of the time.

We've observed that our Dishy consumes more power during large downloads 
than during uploads, which suggests that transmit power isn't the main 
factor here. It appears that it's the signal processing that is needed 
to receive and demodulate the incoming signal with the high bit rate 
data stream that really eats the watts.

Incidentally, with more birds in the sky, Dishy seems to be willing to 
put up with a bit more obstruction nowadays:

Think of this image as viewing our Dishy down its surface normal, 
mirroring the sky. Anything in red is obstruction, anything in white (if 
your background is white, save image and view against a dark background) 
are successful communications with satellites. The obstruction you see 
here is the corner of my roof at home, making up around a quarter of 
Dishy's field of view. The obstruction resulted in a ping loss of 518 
packets out of 635923, or 0.08%.

-- 

****************************************************************
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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