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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