morcheeba
Joined 12 years ago
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Member since
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Recent submissions
Comment · 1 year ago
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.
Comment · 1 year ago
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.
Comment · 1 year ago
>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.
Comment · 1 year ago
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...
Comment · 2 years ago
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.
Comment · 2 years ago
+1 for RTEMS, another happy user!
Comment · 2 years ago
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.
Comment · 2 years ago
Shmoocon had it right providing Shmoo balls.
Comment · 2 years ago
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
Comment · 2 years ago
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...
Comment · 2 years ago
>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.
Comment · 2 years ago
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.
Comment · 2 years ago
The AVP isn't sold in the EU yet.
Comment · 2 years ago
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.
Comment · 2 years ago
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.
Optics & biotech startups, robots, cameras, 3d sensors, GPS, reverse engineering... current project will fly to Saturn.