Fascinating that they chose to use modulated board-to-board Ethernet instead of just running RGMII from MAC to MAC.
msgodel · 12h ago
Ethernet seems far easier to prototype with. There's almost no off the shelf stuff for talking to RGMII whereas Ethernet you can just plug into your laptop for testing. If it's two different teams building things it seems like it would be a lot easier to just agree on Ethernet as the interface and then delay integration testing or release earlier.
numpad0 · 5h ago
RGMII is not some obscure competitor to Ethernet, but rather, Ethernet was designed to be a modular two-part design with "MAC" and "PHY" chips connected via "MII" interface. RGMII is simply the latest version of it.
Many Ethernet-supported SoCs still use various MII style interfaces because it makes more sense to outsource the physical layer to some external chip especially if not everyone is going to use Ethernet.
It's perhaps like the difference between using Thunderbolt vs raw PCIe. You technically shouldn't need Thunderbolt if you're just permanently connecting two things inside a same machine.
Is it smarter to do it proper and make it silicon efficient than just shipping the darn thing ASAP? idk. We'll see.
stephen_g · 4h ago
RGMII requires way more work to run board-to-board (heaps of signals, quite precise length matching, impedance control, etc. on the boards, better board-to-board connectors etc.) and at the end of all that will likely be less robust than just running Ethernet. I'd much rather use SGMII just because it's far fewer signals to match (even if it runs way faster) instead of RGMII.
The chips they're using might already have Ethernet PHYs built in anyway which might also be part of the reason they're using Ethernet.
15155 · 11h ago
A $3 breakout PCB with an RGMII PHY and MagJack on it would solve this problem without resorting to analog communication.
msgodel · 11h ago
Assembly isn't free, either an engineer or the PCB fabricator has to put that together. Also the design isn't free and it's certainly not necessarily going to match the behavior of the device on the other side.
But your laptop's Ethernet adapter comes free with your laptop (both in terms of money and waiting to get it since it's already on your desk) and possibly even more importantly you know the laptop manufacturer and users have QAed it for you so it's absolutely going to behave the way you expect which is important when the device you're designing isn't behaving.
15155 · 10h ago
> Assembly isn't free, either an engineer or the PCB fabricator has to put that together
> your laptop's Ethernet adapter
The device as-designed likely wouldn't work with your laptop's ethernet adapter - hence why the author of TFA placed an isolation transformer and jack ...on a breakout board.
msgodel · 9h ago
Heh I didn't notice it didn't have the isolation transformer. That is odd.
dlcarrier · 2h ago
That connector is way cheaper than something that could carry an RGMII signal without major reflections. It's probably cheaper in the end to have the extra silicon than a better connector, and I don't think you need the magnetics if you don't need isolation.
MOARDONGZPLZ · 13h ago
A lot of this is pretty POC-y. Agree digital to analog to analog to digital is kinda inefficient, and in the abstract MAC to PHY (which is probably what you mean when you say MAC to MAC) with RGMII is probably better. My off the cuff guess is that it is likely the written-up interface is easier to access or requires less diving into internals. Not sure where the RGMII lines are, and depending on the design of the Starlink mini itself (I am ignorant of this) the lines might have been buried deeper and less accessible, who knows.
05 · 5h ago
Sure, then you get to write an MDIO emulator so that it actually detects link and since it's a proprietary system you can't exactly comment out the SMI code.. fun!
jpm_sd · 8h ago
RGMII isn't really designed to go board-to-board, fairly high data rates, and ideally all of the signals should be delay matched. That gets a bit trickier when there are two boards involved. Also I would expect EMI/EMC issues.
I know people do that sort of thing for evaluation kits, but it doesn't seem like a good idea for production.
CamperBob2 · 12h ago
I'm not sure I understand the entire point of the exercise. There's already an RJ45 jack on the Mini, so no need to hack the unit to get access to an Ethernet PHY. And the WiFi router can be turned off via the setup page.
Did they remove support for the Ethernet jack on the Minis available in Ukraine? It looks like it's still present on the WiFi board, next to the power jack.
dogben · 12h ago
They may want to make absolutly sure no wifi signal emit from the device. Turning it off in the setup page is definitely not enough.
The wifi chip may emit signal during boot. The device may get accidentally reset in the field. SpaceX may push an update that messes with the settings.
CamperBob2 · 11h ago
I mean, more power to them, certainly, but WiFi emissions seem like the least of your concerns when you're operating an antenna for satellite comms. There will be no shortage of side lobes at Ku band for anyone who cares to listen.
Cutting down on mass would make sense, though.
MOARDONGZPLZ · 10h ago
It will still draw power with wifi turned off, though much less. The most effective way of reducing the P in swap is to remove the unit entirely
closewith · 12h ago
You might imagine some use cases where mass is a critical concern.
Aspos · 15h ago
I know exactly what power-constrained application you have in mind, Oleg, and I like it.
Given that the blogger is based in Kiev, Ukraine? Good chance this goes on some sort of long range, Predator-style drone.
neilv · 6h ago
I hope that the engineers and scientists contributing to asymmetric warfare technology there aren't designated high-value targets by the adversary.
Wouldn't publicity paint a target on one's back?
stephen_g · 6h ago
Seems likely, just a risk one has to take if you want to actively contribute to a war effort...
neilv · 4h ago
Is one increasing the risk by blogging and YouTubing about it?
burnt-resistor · 14h ago
I wonder how SL plans vary in Ukraine / for use in Russia. Assuming US-like pricing and limitations, for low speed drones, this would work. The gotcha is that for jet or fast prop drones in the 250-478 kts range requires a very expensive aviation plan assuming it's similar to US plans.
dylan604 · 13h ago
Could that not also be part of the support being provided to Ukraine in that those prices are not the same as some commercial account? At the end of the day, the billing department could just not issue the bill, or any other method of meaning Ukraine isn't paying for it.
Aspos · 13h ago
AFAIK US DoD pays for some of the Starlink accounts in Ukraine. The rest are paid for by volunteers at normal prices.
I am not sure - afaik there is a speed limit (assumption of satellite visibility and specific latency?) over which starlink won’t work, right?
It can however be useful for getting the internet without announcing yourself to a swarm of drones?
gruez · 12h ago
>I am not sure - afaik there is a speed limit (assumption of satellite visibility and specific latency?) over which starlink won’t work, right?
The author's youtube channel also contains a video of him doing a speedtest on a starlink mini while driving on a highway.
michaelt · 9h ago
Starlink satellites orbit at 17,000 miles per hour, so I doubt receivers lose signal just from going at a few hundred miles per hour.
Unless there's a software limit built in that turns them off, or the drone's doing some crazy high-G-force acrobatics.
mft_ · 14h ago
Wouldn’t this give Starlink the ability to track and/or turn off operations in real time?
michaelt · 14h ago
Yes, you may recall some controversy a few years back when Musk made some threats along those lines.
There are alternatives if you only need short range, or if you can tolerate high latency. And of course there are fire-and-forget cruise missiles that don't need communications at all.
But there aren't all that many other options. Historically, satellite internet companies like Iridium, Globalstar and Teledesic have not fared well.
maxlin · 12h ago
It was only made to appear a controversy for clicks and Ukrainians (understandably) trying to bend the rules.
The thing came with a clear limit "this thing works in these cells of this big hex grid".
And they drove it off that hex grid. Plan and simple.
Its like if the US-supplied HIMARS came with some built-in limit that it cannot be used to target known Russian nuclear installments, and they'd try to do that.
It's not that those things are unquestionable, but they are limits that would need US consultation as US obviously doesn't want the thing to escalate from being a defensive war to something else.
karp773 · 10h ago
Is Crimea on "this big hex grid" or not? If not, why not?
coryrc · 9h ago
Because the US military/govt has a say in what US companies sell to foreign militaries and that's what the restrictions were at the time. Remember this was early on in the full invasion.
TMWNN · 7h ago
Starlink is prohibited for use in Crimea because of US sanctions against Russia, and not because "Musk turned Starlink off during a Ukrainian attack".
lxgr · 13h ago
Iridium works extremely well for what it was designed for – truly global, low latency communications without requiring a directional antenna. Unfortunately, that also means very low data rates.
It only gained packed-switched data with the second generation satellite network, but data rates are still very low (think hundreds of kbps, and I believe even that needs high-gain antennas).
NitpickLawyer · 12h ago
~Iridium~ devices were bricked in the first days of the invasion, iirc. That's why starlink was such a big deal, and that's why the usmil wanted it "yesterday" after it proved itself in ua. They had to set up a dedicated unit to deal with starlink, as every branch was trying to get it on their own and complicated purchasing. That unit / project was also called starshield, confusing the matter with the other starshield project that uses starlink buses + ng sensor packages.
edit: it was Viasat not Iridium, I got them mixed up.
RF_Savage · 11h ago
Viasat fixed modems got bricked at start of the war in Ukraine and some collateral one's in border areas.
snickerdoodle12 · 9h ago
Interesting how the US goes absolutely ballistic about some random dude violating the "Computer Security Act" on a small scale, but didn't react at all to this massive, incredibly impactful, attack.
mschuster91 · 6h ago
it didn't impact Americans. it impacted us Europeans but at the time this went down we were too dependent on Russia's cheap gas (and, frankly, lacked the military power) to raise the appropriate level of stink.
Hell we let Russia freely execute dissidents (Skripal or the Berlin Tiergarten murder come to my mind) and tolerated a land-grab war by little green men in 2014. Either of these actions would have warranted serious consequences, the Crimea/Donbas grab would be a casus belli if you ask me. But again, we were too busy sucking Putin off for cheap gas.
snickerdoodle12 · 5h ago
so as far as the US is concerned it's fair game to attack US companies as long as it doesn't impact US citizens?
hansvm · 33m ago
As far as the US is concerned, it's fair game to drone-strike US citizens [0,1,2] from time to time.
You are right, thanks. I mixed them up. Iridium is also providing service in ua now, and was unaffected at the start of the war.
mschuster91 · 6h ago
"Some" is an understatement lol. Here in Germany 3.800 (!) wind turbines lost remote control (and thus were forced offline) until the terminals could be changed because their command uplink was via Viasat.
mattmaroon · 14h ago
Yes but they’ve mostly not been doing that (they probably are selling a lot of dishes) and what’s the alternative?
codedokode · 12h ago
Russians also use Musk's satellites and might find the information useful.
Also as I understand, satellites do not work over Russian territory so guess where this can be used.
Andrew_nenakhov · 12h ago
Actually, they do work is Russia. You need account registered in some allowed country and also use RV plan (or maybe it is called 'roam' now). I know some ppl who use it. Was thinking to get one myself, to have a reliable bypass of pathetic russian firewall.
Ray20 · 5h ago
> Actually, they do work is Russia.
Aren't starlink have some kind of geolock?
> to have a reliable bypass of pathetic russian firewall
All data shows that Russia have one of the strongest and best firewall in the world, in many aspects even better than in China. And all the Russians I spoke with say that VPN is not blocked and any service for a couple of bucks does its job.
tguvot · 13m ago
They use it at front lines for fighting Ukraine. Not for reading cnn
littlestymaar · 14h ago
Maybe just for front-line deployment, it would suck to be targeted by a glide bomb because the Russians located some WiFi signal.
mattmaroon · 15h ago
Well the author is Ukranian so I have a guess.
tenuousemphasis · 14h ago
Based on recent events I would guess an explosive-laden drone.
0xbadcafebee · 3h ago
Слава Україні
rozhok · 7h ago
Starlink is already used for «Nemesis» night bombers as well as «Magura» sea drones.
Many Ethernet-supported SoCs still use various MII style interfaces because it makes more sense to outsource the physical layer to some external chip especially if not everyone is going to use Ethernet.
It's perhaps like the difference between using Thunderbolt vs raw PCIe. You technically shouldn't need Thunderbolt if you're just permanently connecting two things inside a same machine.
Is it smarter to do it proper and make it silicon efficient than just shipping the darn thing ASAP? idk. We'll see.
The chips they're using might already have Ethernet PHYs built in anyway which might also be part of the reason they're using Ethernet.
But your laptop's Ethernet adapter comes free with your laptop (both in terms of money and waiting to get it since it's already on your desk) and possibly even more importantly you know the laptop manufacturer and users have QAed it for you so it's absolutely going to behave the way you expect which is important when the device you're designing isn't behaving.
> your laptop's Ethernet adapter
The device as-designed likely wouldn't work with your laptop's ethernet adapter - hence why the author of TFA placed an isolation transformer and jack ...on a breakout board.
I know people do that sort of thing for evaluation kits, but it doesn't seem like a good idea for production.
Did they remove support for the Ethernet jack on the Minis available in Ukraine? It looks like it's still present on the WiFi board, next to the power jack.
The wifi chip may emit signal during boot. The device may get accidentally reset in the field. SpaceX may push an update that messes with the settings.
Cutting down on mass would make sense, though.
Wouldn't publicity paint a target on one's back?
The author's youtube channel also contains a video of him doing a speedtest on a starlink mini while driving on a highway.
Unless there's a software limit built in that turns them off, or the drone's doing some crazy high-G-force acrobatics.
There are alternatives if you only need short range, or if you can tolerate high latency. And of course there are fire-and-forget cruise missiles that don't need communications at all.
But there aren't all that many other options. Historically, satellite internet companies like Iridium, Globalstar and Teledesic have not fared well.
The thing came with a clear limit "this thing works in these cells of this big hex grid". And they drove it off that hex grid. Plan and simple.
Its like if the US-supplied HIMARS came with some built-in limit that it cannot be used to target known Russian nuclear installments, and they'd try to do that.
It's not that those things are unquestionable, but they are limits that would need US consultation as US obviously doesn't want the thing to escalate from being a defensive war to something else.
It only gained packed-switched data with the second generation satellite network, but data rates are still very low (think hundreds of kbps, and I believe even that needs high-gain antennas).
edit: it was Viasat not Iridium, I got them mixed up.
Hell we let Russia freely execute dissidents (Skripal or the Berlin Tiergarten murder come to my mind) and tolerated a land-grab war by little green men in 2014. Either of these actions would have warranted serious consequences, the Crimea/Donbas grab would be a casus belli if you ask me. But again, we were too busy sucking Putin off for cheap gas.
[0] https://en.wikipedia.org/wiki/Anwar_al-Awlaki#Death
[1] https://en.wikipedia.org/wiki/Killing_of_Abdulrahman_al-Awla...
[2] https://en.wikipedia.org/wiki/Killing_of_Nawar_al-Awlaki
Also as I understand, satellites do not work over Russian territory so guess where this can be used.
Aren't starlink have some kind of geolock?
> to have a reliable bypass of pathetic russian firewall
All data shows that Russia have one of the strongest and best firewall in the world, in many aspects even better than in China. And all the Russians I spoke with say that VPN is not blocked and any service for a couple of bucks does its job.