Hacker News: sobriquet9

New comment by sobriquet9 in "FCC Updates Covered List to Include Foreign UAS and UAS Critical Components [pdf]"

sobriquet9 — Wed, 24 Dec 2025 02:16:51 +0000

Are you saying the FCC writes one thing in the regulation, but will enforce something different?

The language I see there now is unambiguous, "batteries". Lithium-ion battery for my impact driver can be used to fly an FPV drone. It does not have an FCC certification because it does not emit any RF, and the FCC never required it to be certified before. Now looks like it can no longer be imported, at least not until either Department of War or Department of Homeland Security deems it not a threat.

New comment by sobriquet9 in "FCC Updates Covered List to Include Foreign UAS and UAS Critical Components [pdf]"

sobriquet9 — Tue, 23 Dec 2025 15:37:53 +0000

"the following UAS components:

    Data transmission devices
    Communications systems
    Flight controllers
    Ground control stations and UAS controllers
    Navigation systems
    Sensors and Cameras
    Batteries and Battery Management Systems
    Motors"

New comment by sobriquet9 in "FCC Updates Covered List to Include Foreign UAS and UAS Critical Components [pdf]"

sobriquet9 — Tue, 23 Dec 2025 15:35:07 +0000

DJI requires activation (through a cell phone app, exposing personally identifiable information) for all their products, even action cameras.

New comment by sobriquet9 in "FCC Updates Covered List to Include Foreign UAS and UAS Critical Components [pdf]"

sobriquet9 — Tue, 23 Dec 2025 15:33:17 +0000

DJI had the list of US no-fly zones that included airports, military bases, prisons, etc. Since DJI is no longer selling drones in the US, they removed that restriction.

New comment by sobriquet9 in "FCC Updates Covered List to Include Foreign UAS and UAS Critical Components [pdf]"

sobriquet9 — Tue, 23 Dec 2025 15:21:05 +0000

The covered list now includes batteries and motors, even though they don't emit RF. Most are just battery cells, wires, magnets, and connectors, with not even a single transistor inside.

They were not previously subject to FCC certification, therefore none are certified, which means none can be imported now.

New comment by sobriquet9 in "FCC Updates Covered List to Include Foreign UAS and UAS Critical Components [pdf]"

sobriquet9 — Tue, 23 Dec 2025 15:13:26 +0000

Rotor Riot sells a flight controller made in USA. Donald Trump Jr. is on the advisory board of Unusual Machines that owns Rotor Riot.

New comment by sobriquet9 in "Electron Band Structure in Germanium, My Ass"

sobriquet9 — Tue, 01 Apr 2025 14:07:34 +0000

I think if you showed not only the point estimate, but also some measure of uncertainty like standard deviation, it should have given you a passing grade. It's hard to say why an answer like 6.8 +- 5 is wrong.

Even if you don't yet have formal statistical chops, it should be at least possible to show cumulative distribution function of results that will convey the story better than a single answer with overly optimistic implied precision.

New comment by sobriquet9 in "The Toyota Prius transformed the auto industry"

sobriquet9 — Sun, 19 Jan 2025 04:21:42 +0000

For the same reasons people are interested in new iPhones, but not last year iPhones. And tax incentives.

New comment by sobriquet9 in "The Toyota Prius transformed the auto industry"

sobriquet9 — Sat, 18 Jan 2025 14:48:58 +0000

Nobody is interested in used EVs, therefore resale values are very low.

New comment by sobriquet9 in "Carlsen quits World Rapid and Blitz championship after dress code disagreement"

sobriquet9 — Sat, 28 Dec 2024 21:55:09 +0000

If it is a completely different game, why are all strongest players the same?

New comment by sobriquet9 in "Something weird is happening with LLMs and chess"

sobriquet9 — Thu, 14 Nov 2024 22:40:27 +0000

This is likely. From example games, it not only knows the rules (which would be impressive by itself, just making the legal moves is not trivial). It also has some planning capabilities (plays combinations of several moves).

New comment by sobriquet9 in "Deep dive: the instability of op-amps"

sobriquet9 — Mon, 28 Oct 2024 16:30:34 +0000

Tape machines predate GPS.

A metaphor should be referring to something common, not something that can be made in theory to fit a different set of requirements, but does not really exist.

New comment by sobriquet9 in "Deep dive: the instability of op-amps"

sobriquet9 — Sun, 27 Oct 2024 13:22:02 +0000

But not DC itself. Even if it goes down to 1 Hz, the circuit in question will saturate in a few seconds, or be in saturation when initially turned on and never get to zero as there is no DC feedback.

New comment by sobriquet9 in "Deep dive: the instability of op-amps"

sobriquet9 — Sun, 27 Oct 2024 13:17:07 +0000

Even when you decode with an SDR, you still need to adjust the receiver frequency to match that of the transmitter, as reference oscillators might have slightly different frequencies that can also slowly shift, e.g., due to changes in temperature. In case of a tape recorder, tape speed during recording and playback can also be slightly different due to mechanical factors.

New comment by sobriquet9 in "Deep dive: the instability of op-amps"

sobriquet9 — Sat, 26 Oct 2024 23:33:54 +0000

FM audio does not carry DC either. PLL in the receiver/decoder will eventually catch up with the constant frequency shift.

New comment by sobriquet9 in "Deep dive: the instability of op-amps"

sobriquet9 — Sat, 26 Oct 2024 18:26:11 +0000

The tape delay methaphor confused me. Tape recorders do not record DC or other frequencies much lower than, say, 20 Hz. So that circuit would run into one of the rails just as quickly as the previous cirquit without DC feedback.

New comment by sobriquet9 in "Deriving the Kelly Criterion to Maximise Profits"

sobriquet9 — Fri, 18 Oct 2024 01:33:17 +0000

An illustrative example to explain ergodicity. Consider the following game. Players start with $100. At every turn, a fair coin is flipped. If tails, the amount of player's money is increased by 50%. If heads, the amount of player's money is decreased by 40%. To play or not to play, that is the question.

New comment by sobriquet9 in "Why are my ZFS disks so noisy?"

sobriquet9 — Sat, 28 Sep 2024 04:08:24 +0000

They also lose data. Especially large files you rarely touch, like family videos. Bit rot on SSDs is real. I backup to HDDs now.

New comment by sobriquet9 in "A Real Life Off-by-One Error"

sobriquet9 — Thu, 05 Sep 2024 03:10:31 +0000

Unless we live in a simulation.

New comment by sobriquet9 in "Pattern of brain damage is pervasive in Navy SEALs who died by suicide"

sobriquet9 — Tue, 02 Jul 2024 17:22:25 +0000

Level IIIA resists penetration from .357 SIG, 9 mm, and .44 magnum. Those are handgun rounds. It may stop some intermediate rounds if you’re lucky, but certainly not full power rifle rounds.

Helmets cannot deform as much as vests before seriously injuring the wearer, limiting their capacity to dissipate kinetic energy. And if you make them too rigid, concussion becomes a problem.