Starlink Satellites Observed

On Apr/25/2020 at 08:35, David Spain wrote :
On 2020-04-25 3:20 AM, David Spain wrote:
The only way not to be co-planar requires some fancy tracking emitter
gear or the ability to shine radially (power hungry). I don't see it,
but if I'm wrong, great! It would render the rest of what I'm about to
say moot. Otherwise, it'd be far simpler to relay across the planes
using a ground station. Now where this works almost ideally is
crossing hemispheres. There isn't nearly as much cable running those
ways and sat-to-sat will beat that in terms of latency easily.
East/West not so much. Of course if you relay across ground stations
closer to the poles that helps.

Well it's fun to speculate and that last statement got me to thinking.
Doing cross plane tracking is tricky until you get into the vicinity of
the poles. There you might be able to use a bi-directional laser (using
a beam-splitter) inclined at X degrees relative to your orbital path to
hit a satellite that is in either a slightly higher or slightly lower
orbit at the polar crossover. Slight is of course measured in 10's of
miles. A goodly distance for these small sats but a smidgen in terms of
orbital distances. If the timing of the orbits is tightly controlled you
can control the degree of slew needed in the emitter to a single axis.
The idea being the laser can cross planes at the poles during the
approach and departure interval for a short period of time. If that
period is long enough to allow overlap between sats in different planes
then you have established continuous contact via switch over for the
entire network, no ground station needed. Beam dispersion would allow
cross linkage to many different orbital planes. Interference could be
eliminated by using different frequencies between non-planar birds.
Regrettably (for us) that info is proprietary to SpaceX.

The ISL could work in two modes. Continuous for your two nearest
neighbors in co orbit (which appear motionless to you) and spot when
hitting a cross plane bird in the polar regions. But for the entire
network it appears continuous since any bird can relay to a polar bird
in its orbital plane. Latency vs ground cable becomes an issue then of
path length vs deltas in the speed of light. You'll win some and lose some.

I don't see why you think that there wouldn't be sat-sat relays for non
co-planar satellites near the equator. Yes, you have to aim at a moving
target, but I think that kind of aiming is a solved problem.


Alain Fournier

On 2020-04-25 8:55 AM, Alain Fournier wrote:

I don't see why you think that there wouldn't be sat-sat relays for non
co-planar satellites near the equator. Yes, you have to aim at a moving
target, but I think that kind of aiming is a solved problem.

I didn't say that I didn't. Sure that'd work too. In fact that would be
easier to track since everything could stay at the same altitude. But
you'd have to relay to cross beyond nearest neighbor planes, curvature
of Earth and straight line lasers and all that. But not a big deal though.

Dave

In article ,
says...


On this group, I was told over and over that the magic lasers would
allow SpaceX to make its money linking London traders with Wall street
with less latency with light tracveling in space than any fibre optic
glass cables (where light travels slower) cable traveling under the ocean.

Yes eventually once they get the cross satellite interconnects working.
Here's an article where an expert ran simulations that show Starlink
will have lower latency than existing fiber networks.

https://www.nextbigfuture.com/2018/1...ency-starlink-
satellite-network-will-be-massively-profitable.html

In the interim, the beta testers/customers that are within range of a
Starlink satellite to ground station hop will "just" have satellite
Internet that has lower latency than regular GEO satellite Internet. I
know someone who used to work remotely from home via GEO satellite
Internet (the company paid for it). The service sucked. Not only was
latency horrible, the bandwidth was horrible too. He had to drive
several hours to go to the closest office every two weeks to download
the new builds. It's people like him that would use Starlink now.

Jeff
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On 2020-04-25 6:39 PM, Jeff Findley wrote: I know someone who used to
work remotely from home via GEO satellite Internet (the company paid
for it). The service sucked. Not only was latency horrible, the
bandwidth was horrible too. He had to drive several hours to go to the
closest office every two weeks to download the new builds. It's people
like him that would use Starlink now. Jeff
At one time I had this too. Back then it was a one-way system (400kbps
down) I could self install. Compared to cable Internet is was pretty
awful. But at that time, when I moved to where I live now, it was my
only option vs 28kbps dial-up or the extremely expensive ISDN with
64/128 kbps, depending upon what I wanted to spend. ISDN would have also
cost me an additional one-time installation expense of conditioned
lines. I lived too far from the central office for DSL as it existed at
the time.

I eventually opted for the more sophisticated software sat solution
provided by a third-party over Linux to provide sat access to my entire
home LAN rather than a single PC running Win95. The Windows solution was
garbage and unreliable. The Linux driver, much, much more solid. I then
went the extra step of setting up the Linux box to act as a router on my
net and was able to selectively determine which IP ports went to the sat
driver versus the dial-up modem (this was a one way system which meant
dial-up outbound and sat or dial-up inbound).

With this setup I was able to get work done, since the remote terminal
sessions went through the dial-up modem and large downloads transferred
via the sat connection. However, I can see for your acquaintance who was
doing builds this would have been a terrible solution. There were also
at that time daily download caps there were severe. I can't recall now
exactly what it was but it was laughable by today's standards. Something
on the order of 300MB or so. Once you hit your limit your sat service
was throttled to 47kbps for the remainder of a time period that ran from
5AM-11PM my time. Latency was a joke. ~400ms ping times across the
satellite if I recall correctly. Fortunately I have never been a video
gamer.

I used this half-a-loaf setup (to put it mildly) until finally, after
about 3 years, the day arrived when cable was installed along to road to
my house. I switched and never looked back, even after two way GEO
satellite became available. Even though I gotta say GEO satellite and
dial-up DID give me Internet service across power failures.

That was GEO. LEO Starlink will be a whole 'nuther kettle of fish.

Dave

On 2020-04-25 6:39 PM, Jeff Findley wrote:
In article ,
says...


On this group, I was told over and over that the magic lasers would
allow SpaceX to make its money linking London traders with Wall street
with less latency with light tracveling in space than any fibre optic
glass cables (where light travels slower) cable traveling under the ocean.

Yes eventually once they get the cross satellite interconnects working.
Here's an article where an expert ran simulations that show Starlink
will have lower latency than existing fiber networks.

https://www.nextbigfuture.com/2018/1...ency-starlink-
satellite-network-will-be-massively-profitable.html

In the interim, the beta testers/customers that are within range of a
Starlink satellite to ground station hop will "just" have satellite
Internet that has lower latency than regular GEO satellite Internet. I
know someone who used to work remotely from home via GEO satellite
Internet (the company paid for it). The service sucked. Not only was
latency horrible, the bandwidth was horrible too. He had to drive
several hours to go to the closest office every two weeks to download
the new builds. It's people like him that would use Starlink now.

Yes this make sense. I see from the article they plan to solve the E/W
issue by interim links across the polar plane orbits whenever two
non-planar satellites are essentially at 90 degree angles from direction
of motion. This will allow cross plane connections for some period of
time until the two pass outside the laser beam dispersion cones between
them. This doesn't require any moving emitters. If this is the
architecture (and it makes sense to me) then this would beat ground
latency in most cases of intercontinental communication. But only after
sat-to-sat is working.

Dave

On 2020-04-25 6:39 PM, Jeff Findley wrote:
In article ,
says...


On this group, I was told over and over that the magic lasers would
allow SpaceX to make its money linking London traders with Wall street
with less latency with light tracveling in space than any fibre optic
glass cables (where light travels slower) cable traveling under the ocean.

Yes eventually once they get the cross satellite interconnects working.
Here's an article where an expert ran simulations that show Starlink
will have lower latency than existing fiber networks.

https://www.nextbigfuture.com/2018/1...ency-starlink-
satellite-network-will-be-massively-profitable.html

In the interim, the beta testers/customers that are within range of a
Starlink satellite to ground station hop will "just" have satellite
Internet that has lower latency than regular GEO satellite Internet. I
know someone who used to work remotely from home via GEO satellite
Internet (the company paid for it). The service sucked. Not only was
latency horrible, the bandwidth was horrible too. He had to drive
several hours to go to the closest office every two weeks to download
the new builds. It's people like him that would use Starlink now.

Jeff


Sorry for the poorly formatted post. My bad, although it looked good
going out. Here's my response (again)...

At one time I had this too. Back then it was a one-way system (400kbps
down) I could self install. Compared to cable Internet is was pretty
awful. But at that time, when I moved to where I live now, it was my
only option vs 28kbps dial-up or the extremely expensive ISDN with
64/128 kbps, depending upon what I wanted to spend. ISDN would have also
cost me an additional one-time installation expense of conditioned
lines. I lived too far from the central office for DSL as it existed at
the time.

I eventually opted for the more sophisticated software sat solution
provided by a third-party over Linux to provide sat access to my entire
home LAN rather than a single PC running Win95. The Windows solution was
garbage and unreliable. The Linux driver, much, much more solid. I then
went the extra step of setting up the Linux box to act as a router on my
net and was able to selectively determine which IP ports went to the sat
driver versus the dial-up modem (this was a one way system which meant
dial-up outbound and sat or dial-up inbound).

With this setup I was able to get work done, since the remote terminal
sessions went through the dial-up modem and large downloads transferred
via the sat connection. However, I can see for your acquaintance who was
doing builds this would have been a terrible solution. There were also
at that time daily download caps there were severe. I can't recall now
exactly what it was but it was laughable by today's standards. Something
on the order of 300MB or so. Once you hit your limit your sat service
was throttled to 47kbps for the remainder of a time period that ran from
5AM-11PM my time. Latency was a joke. ~400ms ping times across the
satellite if I recall correctly. Fortunately I have never been a video
gamer.

I used this half-a-loaf setup (to put it mildly) until finally, after
about 3 years, the day arrived when cable was installed along to road to
my house. I switched and never looked back, even after two way GEO
satellite became available. Even though I gotta say GEO satellite and
dial-up DID give me Internet service across power failures.

That was GEO. LEO Starlink will be a whole 'nuther kettle of fish.

Dave

On 2020-04-26 8:54 AM, JF Mezei wrote:
On 2020-04-25 18:39, Jeff Findley wrote:
Everything will beat GEO Internet service. But if Starlink wants to
proide Starlink service in Canada's acrtic, it will need to build a
ground station there, and that ground station will need to use GEO
satellites to link the ground station to the Internet.

Well they could go the expensive route and install multiple microwave
stations. Not likely. Not likely they will do this at all once
sat-to-sat is working. At the extreme, there aren't that many customers
that far north.

The one thing LEO constellations share with LEO is the uplink capacity
limits which is limited by the spectrum they are allowed to use betwen
satellites and ground stations. The more ground stations you have (with
focused beams for GEO or just limited line of sight for LEO) the more
capacity you have. SpaceX may be able to launch thousands pizza boxes
for free, but it still has to deploy a high number of gound stations,
each providing adequante connectivity to the Internet.

But if you wish to serve a farmer in Otumwah IOWA, you may have your
Chicago ground station that is in range. But Otumwah, if it doesn't
already have FTTH or even DSL, is likely to have cellular. So much of
the footprint aorund a ground station may already have service.

4G-LTE isn't too bad granted and for rural parts of the country 5G
millimeter will have longer range (higher power and towers). It has
always been a bit of a race between cellular and satllite. Because it
has historically been far easier and far far less costly to update
cellular (and terrestrial), it typically wins this race.


And once you have inter-satellite links, the more satellites are
aggregated into one that as sight of a ground station, the less capacity
you have per user.


LEO solves latency, not capacity.


LEO also solves reliability in my case.

Dave

On 2020-04-26 8:54 AM, JF Mezei wrote:

LEO solves latency, not capacity.


I'm not sure I totally agree. Most cellular setups are not designed to
support home networking. There is some router equipment out there that
provide this capability and you can share a connection between
computers, etc. at home but unlike a LEO sat terminal/router, I suspect
performance when sharing a cell connection won't perform nearly as well
as will Starlink when supporting a home LAN.

Try high-def video streaming multiple devices on ONE cell connection and
get back to me. I think even for 5G the jury may still be out, because
of back office issues. It probably will catch up eventually.

Dave

On 2020-04-26 8:54 AM, JF Mezei wrote:

And once you have inter-satellite links, the more satellites are
aggregated into one that as sight of a ground station, the less capacity
you have per user.


I doubt all traffic will congest on single ground stations. No. With
sat-to-sat you can route to and share multiple ground stations along the
polar arc continuously. Intermittently across longitudinal arcs. You
trade off latency for added capacity when necessary.

As I pointed out earlier, traffic across this system will not be
uniform. It will have to make routing decisions based on load. YMMV when
it comes to latency.

Dave

On 2020-04-26 12:22 PM, JF Mezei wrote:

Don't listen to yoru president inject yourself with 5G hype. The
Millimeter wafe tech will have metres of range around bus shelters.
Totally useless for rural. Its the 600 and 700 and 850 that are of use
for rural rech.

Rural cell towers are well over 100ft in height, some of the ones I've
seen. If 5G is line of sight, that's a goodly line. But the common
freqs. probably will be the ones you say.


LEO also solves reliability in my case.

LEO uses the same frequencies that are used by GEO and those frequencies
are affected by rain and snow fade. And those small pizza box sateolite
and smaller receivers likely have weaker transmitters to penetrate
weather. just speculation on my part. But there is a good reason that
before transaltlantic fibre, the terrestrial statiosn to handle overseas
telephone and TV via satellite had HUGE disches half the size of a
mountain: to be weather proof.

I think you are being overly pessimistic. I WAS a user of GEO sat on the
Ku band so I don't have to speculate. Rain fade was extremely
occasional. It had to be raining pretty darned hard to kill it. A gentle
shower wasn't enough. What was weird about it was it was sensitive to
rain at high altitudes not on the ground. You could predict a ground
downpour a minute or so in advance because you'd lose the sat signal
ahead of any rain on the ground. Then the sat would come back whilst
still raining hard on the ground just to let you know relief was on the
way. Sometimes I'd be down for a minute or two, that'd be the extent of
it. Livable. And perfectly fine for me if I'm using it as a backup or
supplement to cable Internet. It's being down the HOURS when there is a
utility power failure that is a problem for me.

Snow fade was effectively non existent except when it accumulated on the
dish. I could have bought a dish heater, but I just brushed off the dish
when it accumulated enough to cause trouble. If I can angle the pizza
box, its mounted high on a pole and its truly flat shouldn't be a
problem. I have a lot of wind where I live to keep it clear... and a broom.

Dave