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morcheeba

Re:A Technical Update on Submarine Cables [pdf] on Sunday September 07, 2025 @03:39PM (#45161463)
AC is only popular because it works with transformers to step up/down the voltage, and it would be more expensive to step up/down a DC signal using electronics (which usually involves converting to AC internally anyway).

AC Voltage is specified in RMS volts, which is based on the average power the AC transmits. The peak voltage (top of the sine wave) is 1.414x the RMS voltage. The insulator only cares about the peak before it breaks down, so because DC doesn't waste time at lower voltages, can transmit more power for the same insulation.

These are coax cables, just by the nature of the external physical shielding required (steel cable sheath). So, the EMF should be contained inside and not affected by the salt water. But, I'm not an expert there and could be missing something.

Re:CT Scans of New vs. Used SawStop on Monday December 09, 2024 @01:25AM (#42363505)
Ah, that explains why there is so much electronics in the cartridge! It seemed a bit like overkill, but returning the cartridge will get them their data.
Re:The Forgotten Story of How IBM Invented the Automated Fab on Thursday November 28, 2024 @02:33AM (#42263292)
>lower the respin costs

You might be interested in structured ASICs, which allow for substantial reuse of masks between different products. At the extreme was a via-only definition product where all interconnects were specified with one mask (and the via masks were among the cheapest to make since they are very uniform).

In regular ASIC development, we've had extra unrouted transistors available to wire in case of a mistake (so hopefully the respin involved just some new metal layers). Techniques like FIB can be used to test fixes to lower the number of respins, too. I'm not sure how much of this was automated to maximize chances of being useful.

https://en.wikipedia.org/wiki/Structured_ASIC_platform

Re:Phased Array Microphone on Friday November 22, 2024 @07:20PM (#42218413)
Not OP, but I looked in to this a few years ago. It was more expensive then, and only went to 20 kHz. Higher frequencies are helpful if you're listening for the hiss of leaking gas, or corona discharge of an electric arc.

The Orin has 6xI2S ports internally, so that would work up to 16*6 = 96 microphones, which is a good number. But it looks like maybe only 3 are brought out & on different dev board connectors [1]? As with a lot of design, the devil is in the details. An FPGA could be easier to configure if you need more than 96 microphones.

My notes:

ICS-52000 $3.50, 20 kHz

ICS-41350 $1.05, 40 kHz

SPH0641LU4H-1 $1.45, 80 kHz+

[1] https://docs.nvidia.com/jetson/archives/r34.1/DeveloperGuide...

The testing for aerospace is extremely rigorous ... For DO-178C level A (Catastrophic failure that can cause a crash or many fatal injuries) we're estimating 2 years to do MC/DC test coverage metric of a fairly basic software system that has two mechanical backups. And that's above and beyond the extensive unit tests.

The main thing that gets checked is the worst-case timing analysis for every branch condition. And there are stack monitors to monitor if the stack is growing in size.

Look at Rapita System's website for more info ... we don't use them, but they explain it well.

Re:How to avoid a BSOD on your 2B dollar spacecraft on Thursday September 26, 2024 @03:17AM (#41655419)
+1 for RTEMS, another happy user!
Re:Apple iPhone 16 Pro and iPhone 16 Pro Max on Tuesday September 10, 2024 @03:11AM (#41498013)
Originally it was because iMessages were free, while SMS were $0.15-$0.20 each. So glad Apple broke that monopoly, along with many other anti-consumer wireless provider restrictions.
Shmoocon had it right providing Shmoo balls.
Re:The Super Nintendo Cartridges on Monday April 22, 2024 @06:46AM (#40113059)
hexdump will automatically does "squeezing" of repeated lines. Follow this with a line count and multiply by the bytes/line and you'll get a rough number of non-repetitive bytes. https://man7.org/linux/man-pages/man1/hexdump.1.html
Re:Flightradar24's new GPS jamming map on Wednesday March 20, 2024 @03:31PM (#39771020)
Two issues to consider:

- GPS positioning is more accurate if the satellites it sees come from a variety of angles (GDOP), so the satellites near the horizon are valuable.

- Aircraft pitch and roll, so a fixed antenna like this would lose precision as it turns to make an approach - just about the worst possible time.

It's difficult to make an antenna with a sharp cutoff to limit the ground vs. above-ground. So, most anti-jammers will use beamforming to cancel out interference in one or more specific directions. So, the null in the antenna moves to follow the interference.

GDOP: https://en.wikipedia.org/wiki/Dilution_of_precision_(navigat...

Re:Apple Terminated Epic's Developer Account on Wednesday March 06, 2024 @04:01PM (#39621390)
>the console manufacturer is actually adding significant value and taking a fair (or not so fair) margin in exchage.

I don't get this. What does a game console manufacturer do that Apple does not? Both provide hardware, system-level APIs, dev systems, developer support, customers. In the old days, game manufacturers didn't even provide a sales channel.

And when you say Apple provides nothing, my above list is pretty solid. In the old days, developer margins were way slimmer, with physical stores taking a 50% cut on top of the console licensing fees and physical manufacturing.

Re:GPS Antenna Mods Make Starlink Terminal Immune to Jammers on Wednesday March 06, 2024 @10:23AM (#39616914)
That's essentially what he's doing. The patch antenna he's using have a null at the horizon, where ground-based jammers would be.
Re:Apple Vision Pro users reporting cracked outer surfaces on Thursday February 22, 2024 @10:06PM (#39476482)
The AVP isn't sold in the EU yet.
Re:The 100MHz 6502 (2022) on Saturday January 27, 2024 @11:51PM (#39162682)
Yep. The 65C02 has a SYNC output that goes high to indicate an instruction is being fetched on the current cycle. Since there is no cache, it's pretty simple to use this to determine the PC.
Re:Anon Boeing engineer reveals why the 737 door blew off on Tuesday January 23, 2024 @07:14PM (#39111869)
Related question: I've seen news reports that the plane had experienced three recent pressurization issues (cabin pressure warnings). Does anyone know what kind of warning this was? Was it:

- too low pressure, meaning that the door might have been leaking before it blew out.

- too high pressure, meaning that the door had extra force on it.

Is it the same as this video? https://vimeo.com/853557623
Re:The Sensor of the 'Big-Sky' Camera on Saturday October 28, 2023 @02:17AM (#38047583)
This is the sensor for the custom camera used to film content for The Sphere - a 316MP sensor capable of shooting HDR at 120FPS. The single CMOS chip is about the size of a 3.5" floppy. Technical paper at https://www.mdpi.com/1424-8220/23/20/8383
That was my first thought, too. My ideas was to make the plastic UV-curable so it would become rigid and not require inflation. I looked it up, and that's what they're doing - UV-curable ribs. It's also not a sphere; it has an inflatable ring. Pictures & paper here: https://asteroid.arizona.edu/KABAND_Inflatable_v3_public.pdf
Re:Log is the "Pro" in iPhone 15 Pro on Wednesday October 11, 2023 @12:28AM (#37840885)
There was a company that did this circa 2003 - SMaL. Their "autobrite" sensor is built to capture log-scale natively. They've switched owners twice since then, but it seems like they're getting more traction in car vision systems than in professional video.

https://www.vision-systems.com/cameras-accessories/article/1...

Re:Magnetism May Have Given Life Its Molecular Asymmetry on Sunday September 10, 2023 @02:37PM (#37458654)
That's really interesting. Chirality is one of the six indicators[1] we'll use to detect life on Titan when we land there in 2034. But Titan doesn't have its own magnetosphere; there is one from Saturn that shields the moon from radiation, but it's not consistent like it is on Earth. I wonder what we'll find!

[1] https://iopscience.iop.org/article/10.3847/PSJ/abfdcf

SPARC is still alive, thanks to its open licensing & established toolchain, for the niche rad-hard space market: https://en.wikipedia.org/wiki/LEON#LEON3FT_processor_core

Although the company is moving to RISC-V for future processors.

>How do we even know the money will be put to good use?

The IBWC is its own thing, directly run under the State Department, with its own engineering staff and field offices.

When we give similar water/sanitation aid to other countries, it goes through the USAID branch of the State Department. The US sends its own experts who live in the countries and direct the money to the best possible uses. https://www.usaid.gov/water-and-sanitation/us-global-water-s...

Good explanation! For completeness:

In an Ion jet, the energy comes from (usually) solar power and the gaseous fuel provides the bulk. These are even weaker because of the limited instantaneous power that can be generated to feed it, but they are very efficient in how much thrust they can provide per propellent weight. Some versions (like arcjet) are a combination chemical rocket/Ion jet.

Re:Maker Faire Bay Area Returns on Wednesday July 12, 2023 @10:37PM (#36704401)
Favorite Dale story: I had a booth at the first Maker Faire. As things were closing down on the last night, I was waiting at the front gate for a taxi back to the hotel. Dale saw me, and with no idea of if I was a presenter or an attendee, and no idea of where I was going, offered to drive me wherever I needed to go. Just pure awesome.
For a typical 70AHr car battery, the 1 mA from this monitor will take 8 years to drain the battery. When you get a "25% remaining" alert, you only have 2 years to recharge it! No, seriously, the self-discharge is about an order of magnitude greater than this monitor.
Re:Man found UC Berkeley skeleton in 2021 on Thursday June 15, 2023 @09:31AM (#36340212)
But we're talking about UC Berkley here - how image-conscious could they be after they hired John Yoo, the Torture Memo guy?
If the spectrum of the LEDs match the sensitivities of the eyes, then everything is fine. But LEDs are narrow spectrum; they won't reproduce color the same way as a broad spectrum light source will.

As for LED screens, those are emissive and work great for simulating any color. However, they are not good light sources for lighting objects because they're narrow spectrum.

If the object you're lighting up is broad-band reflective (like paper with broadband black pigments), then everything is good. But as soon as you get narrow-band pigments, colors are going to be distorted.

Me, too. My two HP48s are finally starting to fail after 30 years of use.
You can probably replace this with a threaded IR cut filter that screws on to your lens.

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