C🅰️tSE Profile picture
Jun 24 9 tweets 7 min read Read on X
Looking at the antenna elements ( printed dual polarization dipole antenna) and the frequenzy used
(DMSP)

We could be looking at one of the ALT/dual use cases being an MPAR Multi-function Phased Array Radar (MPAR)

1/n


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What type of tricks might such an array be capable of?

Just like BlueWalker 2 was built in a reverse communications experiment there are more of those. One has an array here in Sweden.

2/n


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Here are some of its trick. If it was out in space looking in it would add another dimension of monitoring the surface.

3/n

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Here are some more.

Add to this skill-set the ability to do radio communications, like 3gppp 5G and you have a very versatile tool.

Even more so if the entire satellite is software dfefined.

Like the EISCAT radars the BB1s will be in a certain relative configuration initially.
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How did I learn of EISCAT you might wonder?

By browsing the internet intensively for the type of antenna elements I see in ASTS imagery.

These. They certainly look like printed dual polarization dipoles most likely angled a bit.

5/n

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A disclaimer is in place in that no official coms from company exists about other use cases than communications.🤫

So my post is speculative ofcourse.
And if this dual use is why they prioritized the FPGA line remains to be seen.

But to me it shows the opportunity of dual use.
Antenna elements comparison.

Which is what lead me down this rabbit hole along with the ground network frequency used and a few other things.

If I happend to be right:

All my sources are open, none are MNPI, one company rep knows my identity and I truly am just a 🇸🇪 farmer👩🏼‍🌾


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A third type of printed dipole
MPAR (Multi purpose Phased Array Radar) antenna that can be considered intermediate type of the two shown above. This one is for much higher frequencies and thus smaller. But has the printed dipole flange concept, just crossed.


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More from @CatSE___ApeX___

Jul 26
Let’s unpack this $ASTS picture.

First and foremost 150+ heroes building revolutionary technology.

Many Thanks to the @AST_SpaceMobile staff.

🧶🐈‍⬛

1/n Image
It is the same guys as in this picture from january.

But a few things have progressed.

Notice the evolved (as in much more simple & easy) contraption to furl an array on the left.

2/n
Noteably we’ve got two of those.

So parallell workflows / stations.

Highlighted them in yellow on the recent picture.

Remember: Initial pilot of 5 is as much about a pilot to ramp up the factory production rate as it is to test flying the new birds.

(Closeups are older)

3/n

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Read 11 tweets
Jul 11
There was a meeting between FCC and AST SpaceMobile representatives on July 8th 2024.

What can we learn from the Ex Parte filing?

1/n


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”The parties reviewed the current status of AST SpaceMobile’s unopposed amendment, filed on March 11, 2024, converting its Petition for Declaratory Ruling seeking market access to an Application to Launch and Operate under the jurisdiction of the United States (“Amendment”)2”
2/n Image
ASTs pending amendment is unopposed.

This is very rare.

You can compare and contrast with Space-X petition to bend the rules to fit their system. Which everyone but T-mobile disagees with.

But no one contested SpaceMobiles amendment to make the constellation US flagged.

3/n
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Read 14 tweets
Jun 21
Might be a good time to compare AST SpaceMobile constellation to Space-X Starlink 2GHz VLEO.

🧶🐈‍⬛

1/n
For Elon Musk financing his Mars transportation system needs to maximize payload to orbit.

For Abel Avellan designing an efficient system to connect the unconnected is the purpose drives him to keep total payload down.

2/n
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Elon wants 7,500 satellites at VLEO orbits 340km at any one given time.

He has onboard eNb

Abel Avellan wants 168 larger satellites at 715-740 km altitude.

He has terrestrial gNb

This is dramatically different in several ways.

One is more sustainable and efficient.

3/n Image
Read 22 tweets
Jun 1
There are different portions of lowband spectrum that BlueBirds block 1 and BlueWalker 3 can use.

The range has public safety and commercial cellular spectrum in it.

🧶🐈‍⬛

1/n
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Back in 2020 plan was 617-960 range. In 2024 the plan is 617-960 MHz range. Same.

Micron antenna elements are c-c 161 mm. That is optimized for ~930 MHz if You space the phased array at 1/2 wavelength.

Consistent with that range.

2/n
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In the schedule S from March 2024
the range is the same. 617–960.

3/n

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Read 10 tweets
Jan 3
Starlink v2 mini. Some performance measures. ”7Mb” (7mbps DL?) per cell

We can also compare gain levels:

Starlink v2mini 29–38dBi
BlueBird block2 40-47 dBi


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Unit economics of AST satellites.

Throughput per beam is in ASTs case (as in Elons) bandwidth dependent.

Just that AST gets much more of each MHz fronthaul due to much higher Area Spectral Efficiency. (Smaller cells and higher modulation).



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Note that Mb is Mbps in Elons tweet.

Per beam.

That is an SE of 7.2/5= 1.44 bits/Herz
AST SE is 2.8 last test. (14/5)

AST has 2800 beams on a BB2
Starlink has 48 beams.

Basically AST SE is twice that of starlink so they compare like 5600-48

~100x diff in throughput per sat.
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Read 25 tweets
Dec 24, 2023
Starlink v2 design.

Some analysis.

40x40 (1600 antenna elements).
At ~8.8 cm spacing.
Seems optimized for ~1,700 MHz
(Midband / S-band)

For comparison BW3 / BB1 s are
90x90 Lowband elements.
At ~16.1 cm spacing.

1/n


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This has some implications.

The v2 mini will use spectrum with worse propagation charachteristics and larger atmospherical attenuation.

V2 will use a phased array that has fewer elements which means much wider beams and much lower directivity.

2/n
Space-X will likely solve this by using a more narrow field of view, with a small set of beams pointing down.

Spacex design will not allow for a high spectrum reuse.

Cell sizes will look rather like this in comparison.

All the users in a cell get to share the spectrum.

3/n Image
Read 6 tweets

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