C🅰️tSE Profile picture
Sep 21 8 tweets 2 min read Read on X
Applications in all four phases.

Observe - sensor input
Orient - coms
Decide - more coms
Act - electronic warfare

Communications use cases but also non communications use cases.

The specs of a set of formation flying BB1 FPGAs makes them FF-SAR FoPen AKA FOLPEN capable.

1/n
Things has molecules in them. They react to electromahnetic fields differently.

And you can add resolution/ signature by formation flying, by dual polarization and by large bandwidth.

AST does all of that. ✅✅✅👀

2/n
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Hypothetically such arrays can collect very high res data of the world under their area of coverage. Intermittently and report by means of AI any changes.

Any new soldier, vehicle or mine down to 0.5 metee depth.

This would evaporate much of the fog of war.

3/n
This is one of many hypothetical non-coms Department of Defense use cases of sets of large phased arrays in BB1 frequenzy bands.

These use cases are worth Billions USD each in case of war.

4/4
@NathanBabb14 SWIR and Electro optical is good at identification. And SWIR is good at seeing through haze / clouds

But FOPEN radar sees through foliage and shallow soil.

And does detection and Recognition well.

2/n
@NathanBabb14 For a ”skynet” type ominpresent AI powered network of sensors you need to combine into a system of systems. Where some add recognition some identification some detection and do that in all parts of elektromagnetic spectra

2/n
@NathanBabb14 As the systems you allude to is well known the peer adversary hides its assets from those sensor under soil and under foliage.

An satellites based FOLPEN radar takes that possibility away from the enemy and make them subject of precision strikes wherever they hide.

4/n
@NathanBabb14 That does not negate the value of other types of earth obvservation, eo, systems.

On the contrary they are subject to network effects and adding systems w new capabilities to such system of systems increases their aggregate value.

5/5

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More from @CatSE___ApeX___

Sep 24
BlueBirds have all flipped to radar cross section large.

They also exhibit this type of increase
in drag.

I conclude that detumbling was succesful and that the payload now consistently displays a large radar reflecting cross section towards earth.

Likely still inside the LVAs.
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BlueWalker 3 exhibited the same signature change of increased drag coefficient and a RCS flip 2022-10-06

~ Launch + 26 days.

The 5 BB1s are all there Launch +10 days.

Practice makes perfect.

2/n Image
The 5 birds all keep communicating in the ~450MHz range on TT&C channels.

Nothing noteworthy there, just doing what BW3 did.



3/3 network.satnogs.org/observations/?…
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Read 9 tweets
Sep 15
Constellation level aggregated out of band emmission interference is a showstopper for Starlink.

This is due to crazy big leakage in adjacent bands/channels.

So when constellation increase from 300 to 4500 (15x) they need to cut radiated power down to 15%
The system can’t scale Image
There is a term for such a system:

Non-scalable architecture. In technical contexts, this is often referred to as negative scaling or diminishing returns.

2/n
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Two. 2.

Major changes to the SCS R&O killed starlink d2c

One is that the proposition of co-primary licenses was changed to SCS being on secondary basis.

Other primary users (read terrestrial MNOs) enjoy total protection.

Starlink can use PCS on a _non_interference basis.

3/ Image
Read 8 tweets
Sep 14
Here are some Carrier to noise specifications of AST SpaceMobile.

In a filing today to the FCC Starlink reveals more of their d2c system.

Click link twice.

1/n licensing.fcc.gov/myibfs/downloa…



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Space-x Starlink d2c will drop from being able to do 5dB SINR (voice) to 0dB (texts)

If they were to comply with FCC rules.

We can now compare this to $ASTS.

2/n

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Interesting that Starlink squeak about first responders this and that (hint they’re on First Net so will not use this SCS at all).

They do not like AST simply reply with all their specs.

Like so:

22dB Carrier signal to interference and noise. When in compliance with FCC rules.
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Read 5 tweets
Sep 14
Scotia analysts apparenly read some of the DD shared by the SpaceMob community.

If You want Alpha or ”edge” investing in the nascent SCS market, so should You.

Previously thought by many to be the more technically advanced satcom operator Starlink is not getting approval.

1/n
🐾 ACLR. Adjacent Channel Leakage Ratio.

Recent requests by Starlink and some math (I was more kind to them than RKF engineering)

Is for Starlink ~-24.6 dBW/m2/MHz
And for AST ~-45 dBW/m2/MHz

This relates to quality of RF equipment.

A 20dB delta.

2/
It’s important to understand how AST beats Starlink by a lot in multiple different dimensions.

ACLR is focus in the frequenzy domain. How good a system is at not spamming adjacent _channels_.

And the 20dB difference is log scale.

AST is 100 times better.

3/
Read 25 tweets
Sep 2
A few aspects of a NTN system design affects the area spectral efficiency of the system.

I have touched on them and how they relate to Shannons law.

High directivity that creates narrow beams and small cells is key.
See my pinned tweet.

Then there is also interference.🧶🐈‍⬛ Image
We can think of this as the area spectral efficiency aSE as the main metric by which MNOs will choose which Satellite Network Operator Mobile to work with.

And interference is the metric by which regulators select which SNO-Ms are allowed to operate at all.

Gain affects both
/2 Image
Lets consider this image.

It shows the wide beam of smaller arrays (from 2 antennas wide) and the narrow beam of a medium sized array (up to 64 antennas wide)

Creating a beam cell we use the central strongest part of the beam marked in red and blue.

Narrow is good for aSE

/3
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Read 22 tweets
Aug 24
T-Mobile and a Freudian slip.

Decimation. What is that?

🧶🪓🐈‍⬛

Adhering to interference regulations of aggregate OOBE PFD limits would require a deficient system, such as Starlink d2c v2 mini, to use very wide guard bands and/or throttle (shrink) their power.

1/n
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PCS spectrum block that Starlink and T-Mobile intends to use is very narrow to begin with this has a large impact.

They need to maximize its use in power and in bandwidth to make the system profitable.

If they do that with deficient / sub par technolgy it affects others.

2/n Image
Decimation is a disciplinary process of the state with three distinct purposes:

1. Discipline and Order
2. Punishment for Failure or mutiny
3. Reassertion of Authority

It was in the context of the Roman army used to maintain order and

>ensure adherence to standards<

3/n Image
Read 22 tweets

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