[Starlink] Main hurdles against the Integration of Satellites and Terrestial Networks

[Alexandre Petrescu]

Le 15/09/2023 à 19:52, David Lang via Starlink a écrit :
> On Sat, 16 Sep 2023, Ulrich Speidel via Starlink wrote:
>
>> On 15/09/2023 11:29 pm, Alexandre Petrescu via Starlink wrote:
>>>
>>> I must say that I dont know whether the original 'DISHY' is simply a
>>> dish antenna with an analog amplifier and maybe some mechanical motor
>>> steering, or whether DISHY includes a computer to execute some 
>>> protocol,
>>> some algorithm.
>
> In addition to that Ulrich says, the dishy is a full computer, it's 
> output is ethernet/IP and with some adapters or cable changes, you can 
> plug it directly into a router.
>
> There are numberous teardown videos on youtube now, for both the 
> original and the 1st of the rectangular dishys, they will show you how 
> complex the system is.

Thanks for the note.  It's always interesting to look at teardowns.

The Ethernet/IP capability in the antenna box is very promising.

If I had one, the first think I'd do is to use wireshark to listen on 
that Ethernet port to see whether it sends Router Advertisements (IPv6).

People say IPv6 is supported but there are many ways in which IPv6 can 
be 'supported', and some are better than others, not the least being 
NAT66, IPv6-in-IPv4 and the prefix length (64 or not).  And DHCPv6 of 
course.  Native vs non native IPv6, in short.

Alex

>
> David Lang
>
>  >
>> It's a phased array, not a dish, even if it looks like one. It 
>> consists of 100's of fingernail-sized antenna elements that:
>>
>> * during transmissions, have an individual phase delay added to the
>>   signal transmitted from that element, in order to permit
>>   transmission of the combined signal from all elements into a
>>   particular direction.
>> * during reception, have an individual phase delay added to the signal
>>   collected by that element, before the signals are added to obtain
>>   the combined received signal. This allows reception from a
>>   particular direction.
>>
>> Dishy's main direction of transmission / reception is therefore not 
>> its surface normal - this simply points to the area of the sky where 
>> Dishy expects to see most satellites (a function of geographical 
>> latitude and constellation design - essentially straight up in the 
>> tropics, and elsewhere in the direction of the 53rd parallel, which 
>> corresponds to the predominant orbital inclination in the Starlink 
>> fleet). The actual tracking is then done with the phased array 
>> without mechanical movement by Dishy.
>>
>> From what I've seen, Dishy seems to consume more power on receive 
>> than on transmit - that's if you actually download stuff. This is 
>> somewhat counter-intuitive if you're used to putting link budgets 
>> together. But I'd attribute that to a higher degree of digital signal 
>> processing required on the receive and demodulation path.
>>
>>
>
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