Starlink Internet Connection equipment - Home/Office user

[vsatman]

I don't have an answer regarding reuse, but to piggyback on your post, I get different frequency amounts[/url] than MIT, at least for Starlink.  By my count, the down/up ratio is 2:1 rather than 4:1.
User Down: 2 GHz total (10.7 - 12.7 GHz, agrees with MIT)
User Up:  1 GHz total (12.75 - 13.25 GHz and 14.0 - 14.5 GHz)
Gateway Down:  1.8 GHz total (17.8 - 18.6 GHz, 18.8 - 19.3 GHz, and 19.7 - 20.2 GHz)
Gateway Up:  2.1 GHz (27.5 - 29.1 GHz and 29.5 - 30.0 GHz)
Would welcome being corrected.

1) User Up is only  500 MHz  14.0 - 14.5 GHz  (12.75-13-25 as I know are BSS frequency - only broadcast according ITU)
2) You forgot about polarisation.
Between UT and Satellite  only one polarisation (LHCP)  will be used
But between Sat and Gateway both  Right and Left  . It mean we have  this frequncy twice
Please look for frequency plan  from first Space X filing (Attachment S) attached

[gongora]

Maybe someone knows the answer - how many times will the frequencies in the StarLink beam be reused?

It's in the fourth column of the table you attached: 4-5 times.

that is an estimate

[gongora]

From the 2018 docs

[RedLineTrain]

Thanks, vsatman and gongora.  At one time, I picked through these filings and the back-and-forth between the FCC and SpaceX.  But the most recent modification filing in April appears to wrap up all of the approved and recently requested changes.  See the Schedule S.

So to recap what appears to be the case:

(1) user up really is 1 GHz; and
(2) both left and right polarities will be used in all bands.

Is this correct?

[vsatman]

Thanks, vsatman and gongora.  At one time, I picked through these filings and the back-and-forth between the FCC and SpaceX.  But the most recent modification filing in April appears to wrap up all of the approved and recently requested changes.  See the Schedule S.
So to recap what appears to be the case:
(1) user up really is 1 GHz; and
(2) both left and right polarities will be used in all bands.
Is this correct? 

Thanks, RedLineTrain and gongora.

What I see in this files  (Thank`s for it very much!!!)
(1) "user up"  really is 2 (!!!) GHz;  Please see Rx01 + Rx02 + Rx06 + Rx05,  each 500 MHz  Total 2000 MHz (double from first version)
 (2)  left and right polarities will be used in  Ku band  only for  Uplink from UT to Satellite ,
but  for Downlink  from Sats to UT  I see only one polarisation  Look Channel ID CUD1..8
(3)  In Ka Band links Sat - GW  both polarisation will be used
(4)  Band for Gateway Uplink are  Rx07, 08 , 09,  10 = 1600 +1600+500+500 =4200 MHz (+ 200 MHz)
(5) Band for Downlink  from Sats to UT   is 2000 Mhz ( 8 x 250 MHz , the same as for first Version)  only one polarisation
(6) Band for Downlink  from Sats to GW   is 2250 Mhz ( 9 x 250 MHz the same as for first Version), both polarisation will be used
 
Now Starlink is good prepared for symmetric traffic  (capacity for uplink and downlink  by UT are equal ) .
Consumer Internet traffic normally is asymmetric with ratio 4-6 (Download more as Upload) . 
Symmetric trafic or more Uplink capacity is needed if you need video (specially High resolution video) translation from  UT  -

Drones and another unmanned devices???   It uses terminal with USAT  (ultra  small aperture terminal   30 cm diameter dish)
 see
//The Viasat ArcLightŪ system is the key. This mobile satellite broadband system uses a spread spectrum waveform
here https://www.viasat.com/services/airborne-mobile-broadband...

this  changes in StarLink very interesting... :-) 

[oldAtlas_Eguy]

As far as the UTs utilizing both RHCP and LHCP I think it has been solved in a low cost antenna design features. Here is a paper about a Ka band design.

Low-Cost Ka-band Switchable RHCP/LHCP Antenna Array for Mobile SATCOM Terminal https://ieeexplore.ieee.org/document/8292835
Published in: IEEE Transactions on Antennas and Propagation ( Volume: 66 , Issue: 5 , May 2018 )

Unfortunately only if you are a IEEE member you can read the publication. But It demonstrates that there are low cost solutions out there. For the UT it would likely not operate simultaneously on both RHCP and LHCP. But to switch back and forth between them to pick the lowest usage clutter for a given frequency channel. The switching can be very fast in the millisecond speeds.

Added: Although this does beg the question for the UTs what solution is cheaper an RF switch or two independent RF electronics sets and a digital switch in software to pick. In some ways it may be cheaper and use less real estate in the antenna to have two RF electronics sets since the electronics is liable to be cheaper than a Ku band low loss microwave RF switch.

If two electronics sets then at some point in the future with latter UT designs or software upgrades. A full dual simultaneous RHCP and LHCP operations Full Duplex operation could be done.

[su27k]

Another 2 photos of the user terminal, showing them on the roof in different orientations, originally from twitter but was deleted, you can see screenshot of the tweet on the teslamotorsclub forum: https://teslamotorsclub.com/tmc/posts/4799038/

[joek]

...
Now Starlink is good prepared for symmetric traffic  (capacity for uplink and downlink  by UT are equal ) .
Consumer Internet traffic normally is asymmetric with ratio 4-6 (Download more as Upload) . 
Symmetric trafic or more Uplink capacity is needed if you need video (specially High resolution video) translation from  UT  -
...

Several possibilities, including:
- As you suggest, remote sensing-surveillance, including hi-res video.
- UT's as intermediate-interim bounce points (GW-SAT-UT-SAT-GW) until full GW coverage and/or ISL's.[1]
- Cellular or similar remote back-haul.
- ...?

[1] edit: Might get insight into Starlink's intentions with respect to this if we get information on the distribution of UT's.

[joek]

Another 2 photos of the user terminal, showing them on the roof in different orientations, originally from twitter but was deleted, you can see screenshot of the tweet on the teslamotorsclub forum: https://teslamotorsclub.com/tmc/posts/4799038/

Looks like cabling to UT's is POE (Power-Over-Ethernet, as I would expect).  Very much what my POE outdoor cable looks like after unspooling a bit from a tote (not RG-whatever coax).

[northstar]

Another 2 photos of the user terminal, showing them on the roof in different orientations, originally from twitter but was deleted, you can see screenshot of the tweet on the teslamotorsclub forum: https://teslamotorsclub.com/tmc/posts/4799038/

What is interesting to me about those pics is that all of the dishes are pointing the same direction in both photos, but that the direction that the same dishes are pointing has clearly changed between photos.

The  accepted thinking on this board is that the dishes do not physically track the satellite, but that they tilt to the optimum angle for their location/latitude and stay there, and the the satellites are tracked electronically via the phased array elements.  That makes sense.

However, the fact that all of the dishes have changed orientation between photos make me wonder if that is actually the case, or whether they are tracking the satellite as it passes over head.  Could the phased array elements only be beam steering in one direction, and the other direction addressed by the dish pivoting?

Otherwise, why have all dishes pointed the same direction, in any photos that we have seen?

Just trying to make sense of this. 

[Nomadd]

Another 2 photos of the user terminal, showing them on the roof in different orientations, originally from twitter but was deleted, you can see screenshot of the tweet on the teslamotorsclub forum: https://teslamotorsclub.com/tmc/posts/4799038/

What is interesting to me about those pics is that all of the dishes are pointing the same direction in both photos, but that the direction that the same dishes are pointing has clearly changed between photos.

The  accepted thinking on this board is that the dishes do not physically track the satellite, but that they tilt to the optimum angle for their location/latitude and stay there, and the the satellites are tracked electronically via the phased array elements.  That makes sense.

However, the fact that all of the dishes have changed orientation between photos make me wonder if that is actually the case, or whether they are tracking the satellite as it passes over head.  Could the phased array elements only be beam steering in one direction, and the other direction addressed by the dish pivoting?

Otherwise, why have all dishes pointed the same direction, in any photos that we have seen?

Just trying to make sense of this. 

The optimal direction might change as the satellite population changes.

[northstar]

Another 2 photos of the user terminal, showing them on the roof in different orientations, originally from twitter but was deleted, you can see screenshot of the tweet on the teslamotorsclub forum: https://teslamotorsclub.com/tmc/posts/4799038/

What is interesting to me about those pics is that all of the dishes are pointing the same direction in both photos, but that the direction that the same dishes are pointing has clearly changed between photos.

The  accepted thinking on this board is that the dishes do not physically track the satellite, but that they tilt to the optimum angle for their location/latitude and stay there, and the the satellites are tracked electronically via the phased array elements.  That makes sense.

However, the fact that all of the dishes have changed orientation between photos make me wonder if that is actually the case, or whether they are tracking the satellite as it passes over head.  Could the phased array elements only be beam steering in one direction, and the other direction addressed by the dish pivoting?

Otherwise, why have all dishes pointed the same direction, in any photos that we have seen?

Just trying to make sense of this. 

The optimal direction might change as the satellite population changes.

True, expect that it will.  But probably not a lot, or over a short time.  The two photos show the dishes at least 45 deg difference in angle, and all pointed at the same place.

When you look at the user dishes at the site in Boca are they pretty much stationary, or do they track satellites as they go south to north?

[Nomadd]

Another 2 photos of the user terminal, showing them on the roof in different orientations, originally from twitter but was deleted, you can see screenshot of the tweet on the teslamotorsclub forum: https://teslamotorsclub.com/tmc/posts/4799038/

What is interesting to me about those pics is that all of the dishes are pointing the same direction in both photos, but that the direction that the same dishes are pointing has clearly changed between photos.

The  accepted thinking on this board is that the dishes do not physically track the satellite, but that they tilt to the optimum angle for their location/latitude and stay there, and the the satellites are tracked electronically via the phased array elements.  That makes sense.

However, the fact that all of the dishes have changed orientation between photos make me wonder if that is actually the case, or whether they are tracking the satellite as it passes over head.  Could the phased array elements only be beam steering in one direction, and the other direction addressed by the dish pivoting?

Otherwise, why have all dishes pointed the same direction, in any photos that we have seen?

Just trying to make sense of this. 

The optimal direction might change as the satellite population changes.

True, expect that it will.  But probably not a lot, or over a short time.  The two photos show the dishes at least 45 deg difference in angle, and all pointed at the same place.

When you look at the user dishes at the site in Boca are they pretty much stationary, or do they track satellites as they go south to north?

They've always been in the same direction that I've seen. Angled a little to the north

[smisamore]

Another 2 photos of the user terminal, showing them on the roof in different orientations, originally from twitter but was deleted, you can see screenshot of the tweet on the teslamotorsclub forum: https://teslamotorsclub.com/tmc/posts/4799038/

What is interesting to me about those pics is that all of the dishes are pointing the same direction in both photos, but that the direction that the same dishes are pointing has clearly changed between photos.

The  accepted thinking on this board is that the dishes do not physically track the satellite, but that they tilt to the optimum angle for their location/latitude and stay there, and the the satellites are tracked electronically via the phased array elements.  That makes sense.

However, the fact that all of the dishes have changed orientation between photos make me wonder if that is actually the case, or whether they are tracking the satellite as it passes over head.  Could the phased array elements only be beam steering in one direction, and the other direction addressed by the dish pivoting?

Otherwise, why have all dishes pointed the same direction, in any photos that we have seen?

Just trying to make sense of this.

Or, we're looking at two different sets of dishes which are pointing at different parts of the sky for testing/data gathering purposes. It may just be a different part of the roof since it appears to be taken from either a different location or at least at a right angle from the first photo, based on the roofing seams.

[northstar]

Another 2 photos of the user terminal, showing them on the roof in different orientations, originally from twitter but was deleted, you can see screenshot of the tweet on the teslamotorsclub forum: https://teslamotorsclub.com/tmc/posts/4799038/

What is interesting to me about those pics is that all of the dishes are pointing the same direction in both photos, but that the direction that the same dishes are pointing has clearly changed between photos.

The  accepted thinking on this board is that the dishes do not physically track the satellite, but that they tilt to the optimum angle for their location/latitude and stay there, and the the satellites are tracked electronically via the phased array elements.  That makes sense.

However, the fact that all of the dishes have changed orientation between photos make me wonder if that is actually the case, or whether they are tracking the satellite as it passes over head.  Could the phased array elements only be beam steering in one direction, and the other direction addressed by the dish pivoting?

Otherwise, why have all dishes pointed the same direction, in any photos that we have seen?

Just trying to make sense of this.

Or, we're looking at two different sets of dishes which are pointing at different parts of the sky for testing/data gathering purposes. It may just be a different part of the roof since it appears to be taken from either a different location or at least at a right angle from the first photo, based on the roofing seams.

Reviewing the pics, the roofing seams and the cabling, it looks like the same installation, but with clearly different alignments on the dishes, one with them all pointing in the same direction, and one with them all pointing straight up. 

To speculate, I'm guessing that the picture with the dishes turned up facing the sky is them installed but not plugged in and powered up (just point them at the sky!) and the picture with them all facing the same direction is after they have been powered up and done their search to the 'best' alignment.

[Hummy]

Reviewing the pics, the roofing seams and the cabling, it looks like the same installation, but with clearly different alignments on the dishes, one with them all pointing in the same direction, and one with them all pointing straight up. 

To speculate, I'm guessing that the picture with the dishes turned up facing the sky is them installed but not plugged in and powered up (just point them at the sky!) and the picture with them all facing the same direction is after they have been powered up and done their search to the 'best' alignment.

The original poster appears to live in Washington. In that case the best alignment is straight up (Starlink satellites bunch up around 50 degrees latitude). Can anyone identify the logo on a business building in the background on the left photo?

[LouScheffer]

As far as I know, you'd never use both polarities on the same frequency on the same unit. The isolation isn't that good.

JPL routinely uses both polarizations in the same band (though left and right circular, not linear).  This was used on the New Horizons mission - the spacecraft had two TWTA amplifiers, one generating RCP and one LCP.  By using both at the same time they could double the data rate.

This trick only works when the signal strengths in both polarizations are similar.  Typically isolation is something like 20 db, or a factor of 100 in power.  So if the two signals are equal in strength, each channel sees the other as merely a small noise component.  But if one polarization is 100x stronger, it will bleed through the polarizer as strongly as the desired signal in the other channel.  But if both signals are coming from the same source, at the same power, then the isolation is good enough.

So from one satellite to a ground station you could use LCP and RCP simultaneously.  You could probably not use differing polarizations at the same frequency from different satellites.

[DAZ]

Geostationary satellite systems are inherently broadband devices.  You want to limit to the extent practical filtering that would normally isolate most transmit frequencies from the receiver.  Polarization can help accomplish this.  Circular polarization does not allow for frequency reuse although horizontal polarization does allow for reuse of frequencies.  On the satellite, each transponder would be either vertically or horizontally polarized.  This means that 2 different ground terminals could use the same frequency but just opposite polarizations.  This is possible because the transponders on the satellite are just a bent type of device and are using separate transmit and receive antennas.

For the ground terminals to transmit and receive on the same frequency would require carrier in carrier technology.  As the transmit station knows what it is transmitting it can use this to digitally subtract from the received signal its own transmit signal.  What remains is the distant end.  Both ends of the system must do this and it is practical as each ground terminal (satellite is only retransmitting what it received and not demodulating and re-modulating) only has to worry about its own transmit data.  Starlink does not use a bent pipe system.  A Starlink satellite is a distant end.  You would have to use this digital subtraction method on every received signal from every user subtract all the transmitted signals to each user.  Most likely it would be using many times more computational power on each satellite than for all of the other routing and switching functions on that satellite.  This is not only not practical but not necessary.  Starlink will not be frequency limited in the foreseeable future on either its data rates or the number of customers.

[Nomadd]

 One disadvantage of linear polarization is the setup. You have to get the feedhorn rotated pretty precisely to satisfy the sat operator. If the pickup isn't in the perfect dish focus, you can never get to spec and they finally get tired and let you slide a db or two.
 That's one area where scanned antennas are a mystery to me. I've never worked with them except for a radar.

[Robotbeat]

...  Circular polarization does not allow for frequency reuse although horizontal polarization does allow for reuse of frequencies....

No. As far as the physics goes, BOTH allow frequency reuse, but it's easier to do with circular as orientation (about the axis pointing from receiver to transmitter) doesn't matter.