Quote from: Eka on 09/08/2020 07:34 amQuote from: Semmel on 09/08/2020 07:10 amQuote from: gongora on 09/07/2020 05:03 pmI'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.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 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.
Quote from: Semmel on 09/08/2020 07:10 amQuote from: gongora on 09/07/2020 05:03 pmI'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.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.
Quote from: gongora on 09/07/2020 05:03 pmI'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'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.
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.
Quote from: Eka on 09/08/2020 07:34 amIf 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. 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?
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.AbstractA 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.
New(?) SpaceX phased array antenna patent found by reddit: Uni-dimensional steering of phased array antennasQuoteU.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.AbstractA 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.
New(?) SpaceX phased array antenna patent found by reddit: Uni-dimensional steering of phased array antennas
For now. Costs are decreasing rapidly.
https://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: 01425000-5Year of manufactureSerial numberIP rating: IP55Power input: AC 200-240 V (50/60 Hz) @ 33 AShort-circuit current rating: 10 kAMade in USA by SpaceX
Thermal shutdowns affect other usersOfficially, 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.
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.
Quote from: gongora on 10/18/2021 09:26 pmStarlink 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.
...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....
Quote from: gongora on 10/18/2021 09:26 pmStarlink 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.
Quote from: markbike528cbx on 10/18/2021 09:01 pm...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)
Quote from: joek on 10/18/2021 11:03 pmQuote from: markbike528cbx on 10/18/2021 09:01 pm...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.
