Re: [Starlink] Starlink for Tonga?

[Christian von der Ropp <cvdr@vdr.net>]

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And to make things even more complicated Starlink also have to avoid 
emissions within a certain angle towards O3b's satellites in MEO 
(relatively easy as they are close to the geostationary arc) and to all 
its LEO competitors with higher ITU priority which would be OneWeb, 
Telesat Lightspeed, KLEO Connect and before all these a potential 
European LEO constellation should it use Thales' ITU filings (MCSAT-2 
LEO-x) - see 
https://www.itu.int/en/ITU-R/space/workshops/danang-2015/Documents/Presentations/Yvon%20Henri%20-%20NGSO%20Issues.pdf

The more satellites these LEO competitors deploy, the more in-line 
events will occur during which Starlink will have to seize emissions - a 
so far underestimated issue that could severely impair coverage and 
service availability.

Am 08.02.2022 um 11:11 schrieb Ulrich Speidel:
>
> That's an interesting aspect that I hadn't considered! A quick 
> back-of-the-envelope reveals that the GSO arc is at least 15 times 
> beyond a Starlink LEO satellite, and with Friis propagation, that's 
> about 23 dB in terms of difference in path loss, and thus not as much 
> separation as you'd want. Under ITU regs you're competing with noise, 
> not signal ;-)
>
> Either way, I know it's a contested topic even at the regulatory level.
>
> Tonga is at around 20 deg south so could be using anything from north 
> just over zenith to further south, but as I've pointed out, there are 
> other issues here also.
>
> On 8/02/2022 9:58 pm, Mike Puchol wrote:
>> The GSO satellite operators, due to the fact that they have been 
>> there for eons, plus they cannot move the satellites around, are at a 
>> disadvantage with NGSO operators such as Starlink, when it comes to 
>> using the same shared spectrum. The Ku band downlink spectrum 
>> Starlink uses is the same as your satellite TV, thus, if your Dishy 
>> was inline with a Starlink satellite and the line towards the GSO 
>> arc, the satellite would kill all satellite TV in your area.
>>
>> The ITU in its article 22 specifies how NGSO operators must protect 
>> GSO operators, by not generating interference above certain power 
>> levels to or from the GSO arc. For Dishy, this means it cannot 
>> transmit anywhere between the GSO arc elevation and +18° (up), -18° 
>> (down).
>>
>> In Barcelona, the GSO arc due South sits at around 43° in elevation, 
>> thus, my Dishy cannot transmit between 25° and 61° in elevation due 
>> South. However, the protection band begins around an azimuth of 120°, 
>> up to around 240°.
>>
>> In the Equator, the GSO protection band starts due East, and goes all 
>> the way across the sky due West. It also takes out 37° of visible sky 
>> at zenith.
>>
>> Hope this helps!
>>
>> Best,
>>
>> Mike
>> On Feb 8, 2022, 09:49 +0100, Daniel AJ Sokolov 
>> <daniel@sokolov.eu.org>, wrote:
>>> On 2022-02-08 at 01:47, Mike Puchol wrote:
>>>> the biggest impact on Fiji and Tonga is the GSO protection, which
>>>> takes out 36° of usable sky, all the way from East to West.
>>>
>>> Ho Mike,
>>>
>>> would you please be so kind to explain that a bit more?
>>>
>>> Thank you
>>> Daniel
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> -- 
> ****************************************************************
> Dr. Ulrich Speidel
>
> School of Computer Science
>
> Room 303S.594 (City Campus)
> Ph: (+64-9)-373-7599 ext. 85282
>
> The University of Auckland
> ulrich@cs.auckland.ac.nz  
> http://www.cs.auckland.ac.nz/~ulrich/
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