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#80 by Eka on 09 Sep, 2020 14:43
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They don't need to switch satellites, but would need to switch sides. If the com lasers for the side links were placed on a rotatable stalk, then they could retain communications. That stalk would have to be set off to the side so it doesn't interfere with the phased array antennas. Of course that adds complexity and the need for slip ring connections. Best avoided if possible. Otherwise I'm not seeing how unless more than 4 com lasers are present. The issue I see is that switch off interrupts routes, but they are being interrupted all the time. At the switch off time, those links are not needed other than for traffic volume. E/W traffic can go to the next satellite in the same orbital plane.
If you watch the video in @NaN's message #66 above, video pos 1m50s, you can see the links are rather stable satellite to satellite wise from one plane to the neighboring planes. The satellites all kinda move together. This means satellite to satellite links in the network are long lived. The only issue is the sides swap twice an orbit.I've been wondering how the inter-satellite links would work. With optical links, don't the send and receive elements both need to be actively pointed at each other? If so then a satellite sending information can't randomly pick another satellite on some instantaneously calculated optimal path to send the data to, because that other satellite wouldn't know to receive the information. Wouldn't the data need to go over predefined routes within the constellation? With a large number of satellites there could be a large number of defined routes, but near the end points there may need to be some sub-optimal routing for a small number of hops. For really high value routes (New York to London or various other combinations of commercial centers) they could define routes to always keep those as low latency as possible.
My understanding/speculation:
Each sat has 4 laser connections, I assume 2 for the in-plane and 2 for out plane connections. These lasers can track satellites individually, within reason of the pointing of the host satellite.
Sats in the same orbital plane: Here the host sat could potentially switch to further away satellites by slightly pointing the laser to a different sat. But realistically, say each sat is connected at all times to its predecessor and successor in the orbital plane. All sats know where they are relative to each other by communicating with ground stations.
Sats out of plane: The laser trackers have to do a lot of work pointing to the correct sats. Sats that are on neighboring planes move relative to each other. Not sure how this works, but there is probably a fixed rule how the sats are connected and they hand off connections pretty fast.
I know, but do the tracking lasers have 360° field of view? Maybe, but probably difficult to pull off. So they have to hand off every 45 minutes or so. If they swap sides or target entirely new satellites is what I dont know.
If 6 comm lasers were put on each satellite, then they could hand the side links off.
The big issues are how long are those links are down, is it really a problem, how much slewing both com lasers at the same time upsets the satellite, and wear and tear on the flex connectors. -
#81 by Nomadd on 09 Sep, 2020 16:04
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By the time they start deploying lasers en masse, they won't be far from launching in other inclinations. Won't the other inclinations be at slightly different altitudes for traffic reasons? Or maybe slightly elliptical if they're the same period to avoid crossing paths? Or is the orbital simulator in my brain I got mostly from watching Duck Dodgers cartoons way off?
If you watch the video in @NaN's message #66 above, video pos 1m50s, you can see the links are rather stable satellite to satellite wise from one plane to the neighboring planes. The satellites all kinda move together. This means satellite to satellite links in the network are long lived. The only issue is the sides swap twice an orbit. -
#82 by Eka on 09 Sep, 2020 18:44
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Other orbital inclinations likely will have to be at other altitudes due to all the crossing of orbits. Talking between altitudes may require more lasers or they could have a satellite every few satellites link between orbit altitudes using their side comm lasers.
By the time they start deploying lasers en masse, they won't be far from launching in other inclinations. Won't the other inclinations be at slightly different altitudes for traffic reasons? Or maybe slightly elliptical if they're the same period to avoid crossing paths? Or is the orbital simulator in my brain I got mostly from watching Duck Dodgers cartoons way off?
If you watch the video in @NaN's message #66 above, video pos 1m50s, you can see the links are rather stable satellite to satellite wise from one plane to the neighboring planes. The satellites all kinda move together. This means satellite to satellite links in the network are long lived. The only issue is the sides swap twice an orbit. -
#83 by su27k on 12 Sep, 2020 04:17
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New(?) SpaceX phased array antenna patent found by reddit: Uni-dimensional steering of phased array antennasQuote
U.S. patent number 10,770,790 [Application Number 15/908,602] was granted by the patent office on 2020-09-08 for uni-dimensional steering of phased array antennas. This patent grant is currently assigned to Space Exploration Technologies Corp.. The grantee listed for this patent is Space Exploration Technologies Corp.. Invention is credited to Alireza Mahanfar.
Abstract
A phased array antenna system configured for communication with a satellite that emits or receives radio frequency (RF) signals and has a repeating ground track in a first direction, the antenna system includes a phased array antenna including a plurality of antenna elements distributed in a plurality of M columns oriented in the first direction and a plurality of N rows extending in a second direction normal to the first direction, and a plurality of fixed phase shifters aligned for phase offsets between antenna elements in the first direction and a gain-enhancement system configured for gain enhancement in the second direction of radio frequency signals received by and emitted from the phased array antenna. -
#84 by niwax on 12 Sep, 2020 10:10
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New(?) SpaceX phased array antenna patent found by reddit: Uni-dimensional steering of phased array antennas
QuoteU.S. patent number 10,770,790 [Application Number 15/908,602] was granted by the patent office on 2020-09-08 for uni-dimensional steering of phased array antennas. This patent grant is currently assigned to Space Exploration Technologies Corp.. The grantee listed for this patent is Space Exploration Technologies Corp.. Invention is credited to Alireza Mahanfar.
Abstract
A phased array antenna system configured for communication with a satellite that emits or receives radio frequency (RF) signals and has a repeating ground track in a first direction, the antenna system includes a phased array antenna including a plurality of antenna elements distributed in a plurality of M columns oriented in the first direction and a plurality of N rows extending in a second direction normal to the first direction, and a plurality of fixed phase shifters aligned for phase offsets between antenna elements in the first direction and a gain-enhancement system configured for gain enhancement in the second direction of radio frequency signals received by and emitted from the phased array antenna.
Interesting. This idea seems so obvious after the fact. If you increase resolution along the orbital planes but not across them, you can resolve more satellites per plane while the separation between planes will always likely stay higher tat between satellites. -
#85 by RedLineTrain on 12 Sep, 2020 14:59
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New(?) SpaceX phased array antenna patent found by reddit: Uni-dimensional steering of phased array antennas
It seems that two years ago, the patent author moved on to Amazon. -
#86 by su27k on 16 Oct, 2020 02:04
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In MainEngineCutOff podcast episode T+171, Anthony mentioned he heard some crazy low cost for a standard Starlink satellite, in the price range of a car, not a Ferrari, but a Cybertruck.
He also mentioned there're rumors that SpaceX has bigger/heavier Starlink bus than the current one, which are used for the SDA missile warning satellite bid, and this fits the speculation that the 1 metric ton tracking satellite in the SDA bid is from SpaceX (see here for related discussion on NSF) -
#87 by su27k on 12 Apr, 2021 16:20
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SpaceX Is Selling Starlink Dish At A Much Lower Price Than What It Costs To Make
https://twitter.com/elonmusk/status/1381273474400800773QuoteFor now. Costs are decreasing rapidly.
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#88 by su27k on 27 May, 2021 04:04
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Some information about Starlink Gateway V3 was revealed in filings to Brazilian regulator Anatel:
Reddit thread 1: Starlink ground station antenna certified by Brazilian regulator, revealing some hardware information
Reddit thread 2: This is how Gateway V3 looks inside the dome
Quick Summary from first thread:Quote from: RichardG867https://tecnoblog.net/445448/anatel-libera-equipamentos-da-starlink-internet-via-satelite-de-elon-musk/
Brazil's telecom regulator Anatel has certified the Starlink Gateway V3 ground station antenna. The certification, requested by Starlink Brazil on behalf of SpaceX, covers two variants of the Gateway V3 which differ in operating frequencies. The certificate reveals that the Ku-band antenna has a bandwidth capacity of up to 4 Gbit/s, and features a built-in modem (whatever that would mean in this context).
An attached picture provides a glimpse into the antenna's underside, as well as the identification nameplate mounted there, which contains the following hardware information:
Weight: 1750 kg (3858 lbs)
Part number: 01425000-5
Year of manufacture
Serial number
IP rating: IP55
Power input: AC 200-240 V (50/60 Hz) @ 33 A
Short-circuit current rating: 10 kA
Made in USA by SpaceX
Attached zip file is filing downloaded from Anatel's website using the step by step instruction here
Attached images are from the 2nd thread, captured from the filing document.
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#89 by gongora on 27 May, 2021 04:43
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They're Ka-band antennas (although technically I guess they dip into the top 200MHz of the Ku-band). According to the slide deck that listed weight includes the concrete base and post.
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#90 by AC in NC on 19 Jun, 2021 06:12
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https://arstechnica.com/information-technology/2021/06/starlink-dish-overheats-in-arizona-sun-knocking-user-offline-for-7-hours/Quote
Thermal shutdowns affect other users
Officially, SpaceX has said that "Dishy McFlatface" is certified to operate from 22° below zero up to 104° Fahrenheit. Temperatures reached about 120° yesterday in Martin's town of Topock, near Arizona's border with California, he said. Though Dishy doesn't go into thermal shutdown until it hits 122°, the dish can obviously get hotter than the air temperature.
"I'm thinking the radiating heat from the ground is effectively cooking the bottom of the dish, [while] the top of the dish is cooked by the sun," Martin told Ars. -
#91 by markbike528cbx on 18 Oct, 2021 21:01
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Being curious (nosey), I looked up the location of the local Starlink Gateway.
See attached FCC license.
When I went to that location I saw that the Starlink gateway antennas are mushroom (dome) shaped.
I didn't get any ground level pics as there was a truck in the driveway and we were on a long car trip.
In the Google earth pic (from April 2021) the flat roofed white building has been there since 2003, so not a Starlink building.
The set of 9 domes are new and I assume to be Starlink antennas.
I am sort of surprised that the antennas are dishes, not phased array (from upthread).
The area is pretty flat. And no the lines on the grounds are not alien Nazca lines, it is dryland wheat farming. :-)
I'm surprised that the powerlines along the road to the north (top of pic) are left in place.
Nevermind, I got my old trig cards out and realized a 40ft pole 208 ft from the antenna is 10.8 degrees, which is lower than the 25 degree minimum for Starlink.
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#92 by gongora on 18 Oct, 2021 21:26
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Starlink is currently using phased array antennas for Ku-band (between satellite and end user), and parabolic dishes for Ka-band (between satellite and gateway), both on the satellites and on the ground.
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#93 by markbike528cbx on 18 Oct, 2021 21:48
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Starlink is currently using phased array antennas for Ku-band (between satellite and end user), and parabolic dishes for Ka-band (between satellite and gateway), both on the satellites and on the ground.
I don't recall seeing parabolic dishes on the Starlink satellites. -
#94 by gongora on 18 Oct, 2021 21:49
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Starlink is currently using phased array antennas for Ku-band (between satellite and end user), and parabolic dishes for Ka-band (between satellite and gateway), both on the satellites and on the ground.
I don't recall seeing parabolic dishes on the Starlink satellites.
They're on the ends (the v0.9 test sats didn't have them, but you can see them on every launch since v1.0 started) -
#95 by joek on 18 Oct, 2021 23:03
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In the Google earth pic (from April 2021) the flat roofed white building has been there since 2003, so not a Starlink building.
The set of 9 domes are new and I assume to be Starlink antennas.
...
Likely that building is backbone provider (Level3, CenturyLink, Verizon, ...). Not unusual to see those out in the boonies along major roads, as that is where power is available and fiber is laid. Many Starlink ground stations have been co-located with such. If you have the specific FCC filing or lat-long information, we could probably identify the provider and its interconnect(s) -
#96 by joek on 18 Oct, 2021 23:09
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Starlink is currently using phased array antennas for Ku-band (between satellite and end user), and parabolic dishes for Ka-band (between satellite and gateway), both on the satellites and on the ground.
May also be using a hybrid phased array? Been quite a bit of work on those for Ku-Ka over the past few years. -
#97 by gongora on 18 Oct, 2021 23:18
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Starlink is currently using phased array antennas for Ku-band (between satellite and end user), and parabolic dishes for Ka-band (between satellite and gateway), both on the satellites and on the ground.
May also be using a hybrid phased array? Been quite a bit of work on those for Ku-Ka over the past few years.
At least for normal operations, they're currently using phased array for Ku-band and parabolic dishes for Ka-band. I guess if someone like DoD wanted to use a Ka-band phased array for a gateway they probably could, but the v1.0 sats don't have phased arrays for Ka-band. -
#98 by Scintillant on 18 Oct, 2021 23:52
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In the Google earth pic (from April 2021) the flat roofed white building has been there since 2003, so not a Starlink building.
The set of 9 domes are new and I assume to be Starlink antennas.
...
Likely that building is backbone provider (Level3, CenturyLink, Verizon, ...). Not unusual to see those out in the boonies along major roads, as that is where power is available and fiber is laid. Many Starlink ground stations have been co-located with such. If you have the specific FCC filing or lat-long information, we could probably identify the provider and its interconnect(s)
Looks like it's at 46.1273134, -119.6840400. Prosser, WA. -
#99 by markbike528cbx on 19 Oct, 2021 18:42
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I linked a copy of the license in my first topic post. It is a PDF, so it didn't expand to visibility. Can't repost it from my IPad 2 :-(...
In the Google earth pic (from April 2021) the flat roofed white building has been there since 2003, so not a Starlink building.
The set of 9 domes are new and I assume to be Starlink antennas.
...
Likely that building is backbone provider (Level3, CenturyLink, Verizon, ...). Not unusual to see those out in the boonies along major roads, as that is where power is available and fiber is laid. Many Starlink ground stations have been co-located with such. If you have the specific FCC filing or lat-long information, we could probably identify the provider and its interconnect(s)
Looks like it's at 46.1273134, -119.6840400. Prosser, WA.