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.
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.
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.
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.
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.
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.
Did Apple really break that monopoly? WhatsApp was released 2009 with the explicit pitch that it was "free SMS". iMessage launched 2011, and with the anti-consumer Apple lock-in, and isn't even much used outside US.
Also free/unlimited SMS was prevalent in many countries before WhatsApp or iMessage. And there were plenty of IMs before that too.
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
- 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.
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.