Starlink : General Discussion - Thread 2

[DistantTemple]

Google cable required a physical route, preferably via existing poles, easements etc, or new trenches, poles and permissions. SX needs none of that.

EM appeals to a lot of markets with Starlink. 1) inaccessible/poor access to existing connections. 2) Higher speed.... assumed to be at a a fair price. 3) Low latency. He was just on E3 talking with Todd Howard, enjoying the company of gamers. The plug for Starlink only came in reply to a question about latency. I think he said <30ms from anywhere in the world! and in a later layer of satellites <10ms NOTE*. He stated it was one of the design criteria, to make it effective for gaming. (As well as talking about how many exceptional programmers started on games.) And I add, as VR enters gaming, and remote working, low latency and bandwidth will be needed.

No there are too many fires being cultivated, all pushing for Starlink-like performance. It will not be ignored.

As for multiple users on one antenna. For blocks of apartments its bound to happen. For offices, schools, hospitals etc, there will be a higher bandwidth connection. etc. So I expect Starlink will offer a suitable product, that can be highly multi user. (Edit: Maybe not alert Comcast that he can hijack their urban subscribers)
*(Seems bonkers to me as I get light taking 66ms to travel 20,000Km, half way round the earth!)

[Ludus]

I'd bet I could get plenty of people in my subdivision (~250 houses) to go in together on a Starlink terminal just to give a middle finger to our local provider...

History suggests otherwise. When Google Fiber rolled out tremendously better service at low prices, they found way less uptake than they needed to make it viable. People just sort of shrugged and continued with whatever didn't require them to make changes or understand the difference between a kilobit and a gigabit.

We'd all make the switch in a heartbeat, but the kind of people who join an online forum to obsesses over the technical details of spacecraft aren't a representative sample of the general population. It seems most people would rather not worry about it.

You haven't seen the level of hatred directed at our local provider, then.  Several of my neighbors are using 4G hotspots, even at a price penalty, to avoid the cable provider. 

Plus, when you have an existing market player able to leverage the force of government to protect its business (see Herb's example) you see "apathy".

This came out as a factor even in Elon’s original presentation of Starlink in Seattle where he was recruiting engineers and didn’t expect it to go public. There was cheering making a few words inaudible over the prospect of replacing the big telecom ISPs. The numbers have always meant urban markets would never be handled for large fractions of customers but Starlink could still be an alternative. The issues kind of balance out. Lot’s of people in cities don’t care enough to switch which is fine since the system can’t handle them anyway. There is capacity to give interested customers in cities an alternative. There are tens of millions of underserved people in rural areas as a base.

[Kragrathea]

Can someone who knows chime in on how many base stations one sat can reasonably expect to talk to at one time? As I understand it a phased array antenna uses signal processing to pick out individual sources. And these sources are high frequency wide band.  There must be a limit to how many a modern signal processor can handle at one time.   

[oldAtlas_Eguy]

The sat would likely not steer its spot over an area. It would likely use the same similar methodology of time share slots for uplink scheduled by the sat by sending the ground terminals their transmission package time slots. This is called Time division multiple access (TDMA). WiFi works in a similar manner.

[Nomadd]

The sat would likely not steer its spot over an area. It would likely use the same similar methodology of time share slots for uplink scheduled by the sat by sending the ground terminals their transmission package time slots. This is called Time division multiple access (TDMA). WiFi works in a similar manner.

I suspected they might do that, since high gain up and low gain down sort of leads that way.
 The problem with it is the routing. It would be good with early sats that just bounce the signal to a ground station, but in the future, when the sats route through each other and they're trying to minimize lag, the conversations are going to be going every which direction. The sat routers are going to make one armed paperhangers look lazy.

[Barley]

Modern WiFi (802.11ac) uses beam forming, a type of phased array.  I'd expect starlink to do the same for the same reasons.

Higher antenna gain gives greater rejection of noise and requires less transmission power.  It would also allow you to reuse frequencies in cells smaller than 1,000,000 km^2.

[Kragrathea]

Wifi doesn't work with 10,000s or 100,000s of simultaneous connections. Thats what a single sat would have to do if everyone who hates comcast puts a dish on the roof.

[Robotbeat]

Wifi doesn't work with 10,000s or 100,000s of simultaneous connections. Thats what a single sat would have to do if everyone who hates comcast puts a dish on the roof.

And?

[Kragrathea]

Wifi doesn't work with 10,000s or 100,000s of simultaneous connections. Thats what a single sat would have to do if everyone who hates comcast puts a dish on the roof.

And?

And so it isn't relevant to the question: How many connections can a phased array sat be reasonably expected to handle at once.

[ZChris13]

Wifi doesn't work with 10,000s or 100,000s of simultaneous connections. Thats what a single sat would have to do if everyone who hates comcast puts a dish on the roof.

And?

And so it isn't relevant to the question: How many connections can a phased array sat be reasonably expected to handle at once.

the relevant stats are how many connections it can be expected to handle, the area that the satellite services, the maximum boxes per area density derived from this, and the general housing density of various zones of population to give that number context

[dondar]

Can someone who knows chime in on how many base stations one sat can reasonably expect to talk to at one time? As I understand it a phased array antenna uses signal processing to pick out individual sources. And these sources are high frequency wide band.  There must be a limit to how many a modern signal processor can handle at one time.   

the process is called "beam forming" and is not different from the 5G designs. I see there are plenty of sufficiently good explanations of 5G on the interweb. Refer there.

Already Ku range bids excellent spacial separation of the sources and "theoretically" even complex modulations can be supported. Hence no need for WCDMA separation. But! Technical realization complexities are a bitch.
Math basis (MIMO communications) was done by the beginning of 2000 though.
there are no fundamental restrictions to support multiple users at the same time, more of it outside of cities (i.e. if direct links are available) the separation process is straightforward. ASICs thanks to the bitcoin craze grew up considerably so there are no restrictions there as well.

[Jcc]

Wifi doesn't work with 10,000s or 100,000s of simultaneous connections. Thats what a single sat would have to do if everyone who hates comcast puts a dish on the roof.

And?

And so it isn't relevant to the question: How many connections can a phased array sat be reasonably expected to handle at once.

the relevant stats are how many connections it can be expected to handle, the area that the satellite services, the maximum boxes per area density derived from this, and the general housing density of various zones of population to give that number context

Another relevant stat is the average number of end users per ground station. Especially for apartment buildings and condos it makes a lot of sense to do connection sharing.

[DigitalMan]

I wonder, once the laser-equipped sats are launched, would it be possible to use one of the lasers to determine altitude?  Perhaps place retroreflectors on some of the ground stations?

It would be interesting I think if you are determined to have a large constellation with a minimum of babysitting. Another element would be using the routine communications between sats to track changes to their relative positions.

edit: I suppose you could measure altitude various ways from a ground station without retroreflectors.

[dglow]

So now the key market is people that could buy service from HNS and Viasat?

I thought the low-latency was the key to unlocking big money in HFT markets.

The HFT telecon market is small. There’s not “big money” there. This idea was never mentioned by Elon or SpaceX, it’s just an internet thing.

Realize that HFT markets have dedicated point to point microwave links that for the most part can get even lower latency.

Over land, yes. Across oceans it's still slow fiber. If SpaceX can get NYC–London under 50ms they'll have a hit.

[Asteroza]

So now the key market is people that could buy service from HNS and Viasat?

I thought the low-latency was the key to unlocking big money in HFT markets.

The HFT telecon market is small. There’s not “big money” there. This idea was never mentioned by Elon or SpaceX, it’s just an internet thing.

Realize that HFT markets have dedicated point to point microwave links that for the most part can get even lower latency.

Over land, yes. Across oceans it's still slow fiber. If SpaceX can get NYC–London under 50ms they'll have a hit.

Apparently the HFT guys are doing shortwave to cut out the fiber repeaters, or at least trying.

https://sniperinmahwah.wordpress.com/2018/05/07/shortwave-trading-part-i-the-west-chicago-tower-mystery/

So the standard to beat is shortwave bounce latency (and the unreliability of the ionosphere).

and for added crazy

http://blogs.reuters.com/felix-salmon/2012/05/04/the-neutrino-arbitrage/

pointing neutrinos THROUGH the earth is probably a shorter distance than a orbital lasercomm relay...

[josephcouvillion]

Any clues as to Starlinks's downlink ground station costs?

It occurs to me that in addition to the low latency market, and the middle of no where market you have the extended suburbs, and other last mile problems market. Starlink doesn't need inter-satellite lasers to serve that market just a downlink station that hooks into existing backhauls in the city.

My area of town has lousy infrastructure the phone lines are crappy, often even for analog phone lines. Cable is also unreliable and prone to outages when it rains. but if I could use Starlink as a super WISP all that broken copper isn't a problem.

[rsdavis9]

Any clues as to Starlinks's downlink ground station costs?

It occurs to me that in addition to the low latency market, and the middle of no where market you have the extended suburbs, and other last mile problems market. Starlink doesn't need inter-satellite lasers to serve that market just a downlink station that hooks into existing backhauls in the city.

My area of town has lousy infrastructure the phone lines are crappy, often even for analog phone lines. Cable is also unreliable and prone to outages when it rains. but if I could use Starlink as a super WISP all that broken copper isn't a problem.

Yup.
I have land 60 miles from boston. I have friends living near there and the cable company just stopped 1/4 mile short of their house. They are at least 2 miles to center of town for dsl. No cable. Cell phone coverage barely. Population 1300.

It will be interesting to see how starlink will allow people like this(60 miles) to hook up and prevent people in the near suburbs(10 miles) from hooking up and saturating the same satellites.

[Mandella]

Any clues as to Starlinks's downlink ground station costs?

It occurs to me that in addition to the low latency market, and the middle of no where market you have the extended suburbs, and other last mile problems market. Starlink doesn't need inter-satellite lasers to serve that market just a downlink station that hooks into existing backhauls in the city.

My area of town has lousy infrastructure the phone lines are crappy, often even for analog phone lines. Cable is also unreliable and prone to outages when it rains. but if I could use Starlink as a super WISP all that broken copper isn't a problem.

I do fully expect there to be rain fade issues with Starlink, just as with existing satellite and cellular coverage. That said, I wouldn't mind being surprised. One mitigating factor might be often loss of signal with traditional satellite is due to one towering thundercloud passing between the ground dish and distant GSO transmitter -- the ability to switch between several different LEO satellites at all times might keep signal loss to a minimum during summer storm time.

[russianhalo117]

So now the key market is people that could buy service from HNS and Viasat?

I thought the low-latency was the key to unlocking big money in HFT markets.

The HFT telecon market is small. There’s not “big money” there. This idea was never mentioned by Elon or SpaceX, it’s just an internet thing.

Realize that HFT markets have dedicated point to point microwave links that for the most part can get even lower latency.

Over land, yes. Across oceans it's still slow fiber. If SpaceX can get NYC–London under 50ms they'll have a hit.

Apparently the HFT guys are doing shortwave to cut out the fiber repeaters, or at least trying.

https://sniperinmahwah.wordpress.com/2018/05/07/shortwave-trading-part-i-the-west-chicago-tower-mystery/

So the standard to beat is shortwave bounce latency (and the unreliability of the ionosphere).

and for added crazy

http://blogs.reuters.com/felix-salmon/2012/05/04/the-neutrino-arbitrage/

pointing neutrinos THROUGH the earth is probably a shorter distance than a orbital lasercomm relay...

Shortwave band antenna networks use more power to operate than several other bands. That is one reason why terrestrial SW, MW and LW radio stations are shutting down in several countries.

[Asteroza]

So now the key market is people that could buy service from HNS and Viasat?

I thought the low-latency was the key to unlocking big money in HFT markets.

The HFT telecon market is small. There’s not “big money” there. This idea was never mentioned by Elon or SpaceX, it’s just an internet thing.

Realize that HFT markets have dedicated point to point microwave links that for the most part can get even lower latency.

Over land, yes. Across oceans it's still slow fiber. If SpaceX can get NYC–London under 50ms they'll have a hit.

Apparently the HFT guys are doing shortwave to cut out the fiber repeaters, or at least trying.

https://sniperinmahwah.wordpress.com/2018/05/07/shortwave-trading-part-i-the-west-chicago-tower-mystery/

So the standard to beat is shortwave bounce latency (and the unreliability of the ionosphere).

and for added crazy

http://blogs.reuters.com/felix-salmon/2012/05/04/the-neutrino-arbitrage/

pointing neutrinos THROUGH the earth is probably a shorter distance than a orbital lasercomm relay...

Shortwave band antenna networks use more power to operate than several other bands. That is one reason why terrestrial SW, MW and LW radio stations are shutting down in several countries.

A frequently cited example is the death of the LORAN navigation beacon network (though there is the occasional noises of eLORAN making a comeback for navigation system diversity in the face of loss/jamming of GPS)

There are other factors as well leading to the shutdown of long range relay microwave such as the former AT&T Long Lines network, though the usual reason is servicing the very remote relay towers in rural areas, compared to fiber optic systems that typically follow existing highways/railways/powerlines and are thus easier to reach and repair. Most of the HFT microwave usage is line of sight to an exchange from a datacenter (though allegedly there were some private HFT lines reusing former Long Lines sites), while the shortwave stuff is generally intercontinental/international distances.

AT&T Long Lines Network

Regaining the latency reduction of reduced relays via Starlink helps anything with realtime considerations, without the private upkeep costs of a Long Lines system, and for the shortwave operators, switching to Starlink avoids the variability of atmospheric conditions affecting your ionosphere bounce performance parameters.