SpaceX будет разрабатывать спутники в Сиэтле

Автор Apollo13, 14.01.2015 11:47:55

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Apollo13

https://twitter.com/jeff_foust/status/1379448725282689027?s=20


ЦитироватьIn another LEO Digital Forum panel, SpaceX's Gwynne Shotwell says the company plans to start polar launches of Starlink satellites this summer. Hopes to have full global connectivity after 28 launches; after that additional satellites will add capacity.



ЦитироватьShotwell: Starlink terminal cost now less that half original $3,000. Expect to get that down to a few hundred dollars in a couple years.


ЦитироватьPanel ends without addressing a near-term issue for Starlink: it's fast approaching its current FCC authorization of ~1,600 satellites at 550 km. What happens if the FCC doesn't soon approve SpaceX's requested modification to allow more satellites at 550 km?

vlad7308

Про цену терминала - очень интересно. Спасибо!
это оценочное суждение

Apollo13

https://www.satellitetoday.com/broadband/2021/04/06/spacexs-shotwell-says-starlink-will-reach-every-rural-u-s-household-in-5-years/


ЦитироватьSpaceX's Starlink internet constellation will be able to serve every household in the rural United States in five years, SpaceX COO Gwynne Shotwell shared Tuesday during a discussion on the future of the industry during the SATELLITE show LEO Digital Forum.
"I do know that my constellation in five years will be able to serve every rural household in the United States," Shotwell said, providing an estimate of about 20 million rural households. "We're doing those analyses for other countries as well. Our focus initially is the U.S. because [customers] speak English and they're close. If they have a problem with their dish, we can get one shipped out quickly. But, we definitely want to expand this capability beyond the U.S. and Canada." 
Shotwell gave an update on Starlink, confirming the operator has roughly 1,320 version 1.0 Starlink satellites currently on orbit that weigh 260 kg each. She said version 1.0 satellites do not have inter-satellite links, but SpaceX is targeting inter-satellite links on its Polar Orbit satellites, as previously reported. 
In terms of the user terminal, an area of high interest, Shotwell said the cost is down to less than $1,500 and a recent second version rollout shaved $200 off the cost. SpaceX subsidizes the cost of the terminal, charging customers $500. "We do see our terminals coming in a few hundred-dollar range within the next year or two," she said. 
Shotwell also said that SpaceX doesn't plan for tiered pricing for customers, in order to keep pricing as transparent as possible. 
Starlink has global reach, but not yet full global connectivity, and is projecting continuous global coverage after 28 Starlink launches, Shotwell said. The company is pursuing a rapid launch cadence for Starlink, and it's most recent launch in late March was the 23rd Starlink launch, and the fourth launch during March. 
The COO was open about the work that needs to be done before Starlink moves out of beta testing, which is named "Better Than Nothing Beta."
"We don't have a timeframe for getting out of the beta phase — more performance marks for that. We still have a lot of work to do to make the network reliable. We still have drops, not necessarily just because of where the satellites are in the sky. We'll move off beta when we have a really great product that we are very proud of." 

Georgea


Apollo13

Итого терминал стоит 1300. 500 пользователь платит сразу. Оставшиеся 800 это всего 7% от абонплаты в течении 10 лет. То есть уже сейчас терминал это определенно не самая значительная статья расходов на Старлинк.

Apollo13

https://www.reddit.com/r/Starlink/comments/ml1f2h/nothing_super_revelatory_but_just_got_an/gtlfojc/


ЦитироватьThroughout the beta program, customer feedback has helped drive some of our most important changes to date as we continue to test and scale the network.
The Starlink team has implemented a number of improvements since our last update. Below are some of the key highlights:

Starlink Expansion
Since rollout of initial U.S. service in October 2020, Starlink now offers limited beta service in Canada, U.K., Germany and New Zealand. To date, we have deposits from almost every country around the world; going forward, our ability to expand service will be driven in large part by governments granting us licensing internationally.

Preventative Maintenance
Recently some beta users saw short but more frequent outages, particularly in the evening hours. This was caused by two main issues— preventive maintenance on various ground gateways, coupled with a network logic bug that intermittently caused some packet processing services to hang until they were reset. The good news is fixes were implemented and users should no longer see this particular issue.

Gateway Availability
As more users come online, the team is seeing an increase in surges of activity, particularly during peak hours. The gateway infrastructure to support these types of surges is in place, but we are awaiting final regulatory approval to use all available channels. Near term fixes have been implemented to facilitate better load balancing in the interim, and this issue will fully resolve once all approvals are received.

Dynamic Frame Allocation
The Starlink software team recently rolled out our dynamic frame allocation feature which dynamically allocates additional bandwidth to beta users based on real time usage. This feature enables the network to better balance load and deliver higher speeds to the user.

Connecting to the Best Satellite
Today, your Starlink speaks to a single satellite assigned to your terminal for a particular period of time. In the future, if communication with your assigned satellite is interrupted for any reason, your Starlink will seamlessly switch to a different satellite, resulting in far fewer network disruptions. There can only be one satellite connected to your Starlink at any time, but this feature will allow for choice of the best satellite. This feature will be available to most beta users in April and is expected to deliver one of our most notable reliability improvements to date.
These upgrades are part of our overall effort to build a network that not only reaches underserved users, but also performs significantly better than traditional satellite internet.
To that end, the Starlink team is always looking for great software, integration and network engineers. If you want to help us build the internet in space, please send your resume to starlinksoftwarejobs@spacex.com.
Thank you for your feedback and continued support!
The Starlink Team

zandr

Про спутники
https://www.theverge.com/2021/4/9/22374262/oneweb-spacex-satellites-dodged-potential-collision-orbit-space-force
ЦитироватьOneWeb, SpaceX satellites dodged a potential collision in orbit
Two satellites from the fast-growing constellations of OneWeb and SpaceX's Starlink dodged a dangerously close approach with one another in orbit last weekend, representatives from the US Space Force and OneWeb said. It's the first known collision avoidance event for the two rival companies as they race to expand their new broadband-beaming networks in space.

On March 30th, five days after OneWeb launched its latest batch of 36 satellites from Russia, the company received several "red alerts" from the US Space Force's 18th Space Control Squadron warning of a possible collision with a Starlink satellite. Because OneWeb's constellation operates in higher orbits around Earth, the company's satellites must pass through SpaceX's mesh of Starlink satellites, which orbit at an altitude of roughly 550 km.

One Space Force alert indicated a collision probability of 1.3 percent, with the two satellites coming as close as 190 feet — a dangerously close proximity for satellites in orbit. If satellites collide in orbit, it could cause a cascading disaster that could generate hundreds of pieces of debris and send them on crash courses with other satellites nearby.

Currently, there's no national or global authority that would force satellite operators to take action on predicted collisions. Space Force's urgent alerts sent OneWeb engineers scrambling to email SpaceX's Starlink team to coordinate maneuvers that would put the two satellites at safer distances from one another.

While coordinating with OneWeb, SpaceX disabled its automated AI-powered collision avoidance system to allow OneWeb to steer its satellite out of the way, according to OneWeb's government affairs chief Chris McLaughlin. It was unclear why exactly SpaceX disabled the system. SpaceX, which rarely responds to reporters, did not return multiple requests for comment for this story, nor did David Goldman, the company's director of satellite policy.

SpaceX's automated system for avoiding satellite collisions has sparked controversy, raising concerns from other satellite operators who say they have no way of knowing which way the system will move a Starlink satellite in the event of a close approach. "Coordination is the issue," McLaughlin says. "It is not sufficient to say 'I've got an automated system,' because the other guy may not have, and won't understand what yours is trying to do."

SpaceX has roughly 1,370 Starlink satellites in orbit and is on track to launch thousands more, with ambitions to build a 12,000-satellite network of global broadband coverage. OneWeb has launched 146 satellites so far, of the roughly 650 it plans to send into orbit for a similar global network, operating in higher orbits around Earth. And Jeff Bezos' Amazon has pledged to join the same race, planning to launch over 3,000 satellites in low-Earth orbit. All companies want to beam broadband internet into Earth's most rural regions to meet increasing demand from consumers and governments alike.

"This event was a good example of how satellite operators can be responsible given the constraints of global best practices," says Diana McKissock, the head of the Space Force 18th Space Control Squadron's data sharing and spaceflight safety wing. "They shared their data with each other, they got in contact with each other, and I think in absence of any global regulation, that's... the art of the possible."
Спойлер
Still, the sharp increase of satellites in orbit, mainly driven by SpaceX's Starlink venture, has moved faster than any authority can regulate the industry for safety. McKissock says SpaceX has made efforts to increase its transparency in orbit; the company currently provides location data of its satellites to other operators. But its automated system for avoiding collisions is a closed book where openness and coordination are needed the most, analysts and operators say.

"What is the point of having it if you have to turn it off when there's going to be a potential collision?" Victoria Samson of the Secure World Foundation says, adding that the void of any clear international framework for managing active objects in space makes it largely unclear who would be held responsible if a collision actually occurred.

Satellite maneuvers in space are common, but worry in the industry is mounting as OneWeb, SpaceX, Amazon, and other companies race to toss more satellites into space. And this Starlink close call isn't the first. In 2019, a European Space Agency satellite had to move out of the way of a Starlink satellite to avoid a potential collision. SpaceX didn't move its satellite because of a computer bug that prevented proper communication with ESA, it said at the time.

With more OneWeb satellite launches planned on a monthly basis, and with planned constellations from Amazon and Telesat in higher orbits than Starlink, the need to establish clear rules of the road in orbit is becoming more urgent than ever. SpaceX looms especially large, not just because of the size of its constellation but because of where it's sending them. "OneWeb and others will have to transit through Starlink to reach their destinations, so SpaceX needs to ensure now that other satellite operators can do that safely," says Caleb Henry, a satellite industry analyst at Quilty Analytics.

McKissock says the 18th Space Control Squadron is fully aware of the industry concerns with SpaceX's autonomous avoidance approach. "So it's been interesting," she says. "But like I said, I'm glad they talked to each other. The scary situation is when one of the operators is not communicative, and then it's just crossing your fingers."
[свернуть]

Georgea

Цитата: zandr от 10.04.2021 08:36:01a collision probability of 1.3 percent, with the two satellites coming as close as 190 feet
Хотелось бы знать, что они понимают под вероятностью столкновения. Если мы представим среднее (вероятное) расстояние пролёта в 190 футов, распределение вероятных местоположений (отклонений от среднего) и площадь проекции аппаратов, то имхо должно получиться на пару порядков меньше, чем 1,3%.

PIN

Цитата: Georgea от 10.04.2021 14:46:36Хотелось бы знать, что они понимают под вероятностью столкновения.
https://public.ccsds.org/Pubs/508x0b1e2c1.pdf

методы оценки там в приложении Е,  где ссылка на регистр используемых. Метод указывается в CDM


Цитата: Georgea от 10.04.2021 14:46:36Если мы представим среднее (вероятное) расстояние пролёта в 190 футов, распределение вероятных местоположений (отклонений от среднего) и площадь проекции аппаратов, то имхо должно получиться на пару порядков меньше, чем 1,3%.

Не зная дисперсию параметров ничего не может получиться.

Georgea

Цитата: PIN от 10.04.2021 15:29:27https://public.ccsds.org/Pubs/508x0b1e2c1.pdf

методы оценки там в приложении Е,  где ссылка на регистр используемых. Метод указывается в CDM
Вряд ли я разберусь, но спасибо.




ЦитироватьНе зная дисперсию параметров ничего не может получиться.
Как сказать... Если дисперсия оч. маленькая, то они так и пройдут в 190 футах. Если очень большая, то автоматически имеем очень малую вероятность столкновения. То есть какие-то грубые границы для рассмотрения имеются априори.

vlad7308

Любые измерения и расчеты имеют погрешности, доверительные интервалы и тп. Отсюда и вероятность столкновения.
Если не проходили это в институте, просто поверьте. Если проходили - освежите знания :)
это оценочное суждение

Apollo13

https://lilibots.blogspot.com/2020/11/capacity-of-starlink-network.html


Цитата: undefinedCAPACITY OF STARLINK NETWORK

Crucial issue for Starlink is the capacity it will be able to provide to its early users. SpaceX has initially requested FCC for initial license of a million user terminals, but that has been recently expanded to five million, as indication of really strong initial demand.
In the US alone, main satellite broadband competitors have roughy 1.6 million subscribers (Viasat has 600000 subscribers and HughesNet has 1000000 subscribers). It is highly likely that many (especially premium) subscribers will want to migrate to Starlink due to much lower latency and lower data caps. Both competitors will probably try to fight back by lowering prices and increasing the speeds in their data plans, since upcoming Viasat-3 and Jupiter-3 launches will triple the available capacity of these Internet providers. But the real question is: how much capacity can Starlink offer with its initial constellation?
The basic parameters known: 1600 satellites at 53 degree inclination at 550km orbit.
According to FCC submitted SPACEX V-BAND NON-GEOSTATIONARY SATELLITE SYSTEM ATTACHMENT A TECHNICAL INFORMATION TO SUPPLEMENT SCHEDULE S document from 2017, satellites will be able to use 35 degree inclination or higher between the user terminal and the satellite. At 550km orbit, each satellite will cover a circle with 750km radius or 1.7 million km2. Note that this information is specified for V-Band constellation (VLEO) at much higher frequency band.
According to the same document, satellite will support 1.5 degree beam spots. That should give ((90-35)/1.5)2 * Pi = 4000 beams. Now, SpaceX will use the low part of the Ku band (10.7-12.7GHz for communication) on initial constellation for subscriber downlink. That is around 2GHz of bandwidth, which maps nicely to advertised maximum of  1Gbps of (downlink) throughput.


Now, 4000 beams x 2Gbps would mean 8Tbps throughput per Starlink satellite. That would be more advanced that Viasat-3 (1Tbps) or mPOWER satellites (1.4Tbps), so something is not right there. Real question is how many beams can each satellite maintain at the same time? There seem to be just four phased array antennas at the bottom of the satellite, but it is clear that there is space for up to eight Ku/Ka band antennas in the future. Elon Musk claimed to have around terabit of useful capacity per launch, providing estimate of 16Gbps per satellite, or 4Gbps per antenna. That seems plausible, because due to available power and spot beam focusing, 2 bits per Hz should be easily obtainable.
The real kicker here is the beam spot size. Assuming 1.5 degree beam radius, that leads to surface spot size of just 14km radius, or 650km2. So on that area, Starlink can provide at maximum 4Gbps downlink bandwidth. Using aggressive 100:1 oversubscription that gives 4000 subscribers at advertised 100Mbps downlink, or roughly six subscribers per km2. Not great, but the competition can support even smaller density. And that is why Starlink cannot be viable competitor for subscriber Internet access in densely or even moderately populated areas.
For initial 1600 satellites, only around 3% will be over the continental US territory at any point in time, or roughly 50 satellites (actual coverage is actually higher because satellites spend more time at higher latitude). Distance between satellites will be over 400km, so user terminals will typically have four satellites in sight. 50 satellites gives less that terabit of capacity over whole US continental territory. With 100:1 oversubscription ratio, that is a million 100Mbit subscribers if they are uniformly distributed across that territory. With 99USD/month, this is just 1.2 billion in revenue.
Note that the available frequency band is not really a limitation here. Due to phased arrays and quite narrow 1.5 degree beams, SpaceX will not run out of frequency capacity. But it has to scale up the number of phased array antennas in the sky. There are only two ways to make this happen: design and launch bigger satellites, or launch more of them. For the initial constellation, it is easier to launch more of them.
With F9, SpaceX can probably maintain a launch schedule of roughly 1500 new Starlink satellites per year (roughly billion of CAPEX per year, 25 launches).  With five year lifetime that gives 7500 satellites and roughly five million US subscribers. But technology does not stand still. V-band will enable smaller antennas that will enable packing at least 16 of them in the same form factor. So technology will not stand still.
All this should make SpaceX really keen to push rollout of Starlink around the world.  To support five million subscribers in US, they will have to pack more antennas, provide lower bandwidth tiers (such as 25/3 plans) and simply, launch more satellites beyond the initial constellation size. 

Alex-DX

Цитата: Apollo13 от 02.05.2021 09:03:49Илон Маск утверждал, что у него есть около терабит полезной емкости на запуск, что дает оценку 16 Гбит / с на спутник или 4 Гбит / с на антенну. Это кажется правдоподобным, потому что из-за доступной мощности и фокусировки точечного луча должно быть легко получить 2 бита на Гц.

Вроде бы цифры были от 17 до 23 Гбит/с в низ.
(23/3 антенны) /2 ГГц = 4 бита на Гц что легко  получить.  ;)

Apollo13

https://twitter.com/Megaconstellati/status/1388758782067544064?s=20


ЦитироватьSomething between 50:1 to 10:1 would be a reasonable oversubscription ratio in 2021, regardless of the access technology. Prior to the emergencce of VoD services such as Netflix up to 100:1 was common but that's no longer viable with the constant streaming throughput.

VSATman

Цитата: Apollo13 от 02.05.2021 09:03:49https://lilibots.blogspot.com/2020/11/capacity-of-starlink-network.html


Цитата: undefinedCAPACITY OF STARLINK NETWORK

К сожалению , автор этого опуса не в теме..

Суровая реальность такова.
best case считаем по Ка банду 
имеем 2 ГГц полосы, 2 поляризации и модуляцию 64QAM (или 6 бит/Гц)  итого 2 х 2 х 6 = 24 Гбит 
но увы у нас есть и worse case в Ку
8 лучей по 250 МГц на спутник (кое где еще и меньше - запрет от радиоастрономов)
только одна поляризация для терминала (см. заявку Спейсов в ФСС)
Модуляция 8PSK которая соотвествует отношению сигнал/шум SNR 9 dB или 3 бит/Гц

итого предел при использовании нынешних терминалов типа Диши это 8 х 0,25 х 1 х 3 = 6 Гбит

Далее надо считать потери на служебную информацию, время переключения между Гейтвеями , время переключения между ячейками, это мелочи, но они то же есть..

Nitro

Цитата: VSATman от 02.05.2021 23:41:01
Цитата: Apollo13 от 02.05.2021 09:03:49https://lilibots.blogspot.com/2020/11/capacity-of-starlink-network.html


Цитата: undefinedCAPACITY OF STARLINK NETWORK

К сожалению , автор этого опуса не в теме..

Суровая реальность такова.
best case считаем по Ка банду
имеем 2 ГГц полосы, 2 поляризации и модуляцию 64QAM (или 6 бит/Гц)  итого 2 х 2 х 6 = 24 Гбит
но увы у нас есть и worse case в Ку
8 лучей по 250 МГц на спутник (кое где еще и меньше - запрет от радиоастрономов)
только одна поляризация для терминала (см. заявку Спейсов в ФСС)
Модуляция 8PSK которая соотвествует отношению сигнал/шум SNR 9 dB или 3 бит/Гц

итого предел при использовании нынешних терминалов типа Диши это 8 х 0,25 х 1 х 3 = 6 Гбит

Далее надо считать потери на служебную информацию, время переключения между Гейтвеями , время переключения между ячейками, это мелочи, но они то же есть..
A почему 8 лучей? Вроде 1024 лучей по 1.5 градуса?

VSATman

Цитата: Nitro от 03.05.2021 00:02:53
Цитата: VSATman от 02.05.2021 23:41:01A почему 8 лучей? Вроде 1024 лучей по 1.5 градуса?
потому что у нас есть выделенные для СтарЛинка  2000 МГц в Ку диапазоне 
и есть Знание (из тех доков для ФСС), что терминал использует полосу 240 МГц,  то есть весь диапазон разбит на 8 лучей шириной 240 МГц, которые могут бегать/прыгать по территории, где могут уместиться 1024 луча, но одноворемнно информация передается по этим 8 лучам (каналам)

cross-track

Цитата: VSATman от 04.05.2021 22:45:06
Цитата: Nitro от 03.05.2021 00:02:53
Цитата: VSATman от 02.05.2021 23:41:01A почему 8 лучей? Вроде 1024 лучей по 1.5 градуса?
потому что у нас есть выделенные для СтарЛинка  2000 МГц в Ку диапазоне
и есть Знание (из тех доков для ФСС), что терминал использует полосу 240 МГц,  то есть весь диапазон разбит на 8 лучей шириной 240 МГц, которые могут бегать/прыгать по территории, где могут уместиться 1024 луча, но одноворемнно информация передается по этим 8 лучам (каналам)
это значит, что одновременно один спутник может физически обслуживать 8 абонентов?
Не все у нас еще хорошо, кое-что - просто замечательно!

Alex-DX

Цитата: VSATman от 04.05.2021 22:45:06потому что у нас есть выделенные для СтарЛинка  2000 МГц в Ку диапазоне
и есть Знание (из тех доков для ФСС), что терминал использует полосу 240 МГц,  то есть весь диапазон разбит на 8 лучей шириной 240 МГц, которые могут бегать/прыгать по территории, где могут уместиться 1024 луча, но одноворемнно информация передается по этим 8 лучам (каналам)
Зачем бегать/прыгать по территории, когда можно просто увеличивать/уменьшать площадь обслуживания в зависимости от нагрузки.

Если предположить что на один герц будет приходится около 4 Бит то скорость раздачи интернета одного канала в 240 Мгц это около 1Гбит/с.   
Как я считаю на спутнике 3 передающих антенны, значит всего лучей на передачу 8*3=24. -> 24 Гбит/с
Ранее сообщали о  максимальной пропускной способности 23 Гбит/с, значит на один герц приходится 4 Бита. :)