81–90 of 104 posts
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What’s the frequency response of that sensor? The datasheet says nothing.
Honestly: don't know. My experiments never had a dependency on linearity.
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And interceptors are more expensive than Shaheds. A $100k interceptor (guessing here) to shoot a $10k Shahed can be an acceptable deal for the side launching the Shaheds.
A $100k interceptor to save a $10 million critical facility against a $10k Shahed is a bargain. You saved $9.9 million dollars. Interceptor economics makes more sense when you reason about the bigger picture. The point is to buy you time to remove the supply chain and the stocks so that you're not trading 1:1 forever. It's a stop-gap, or at least it's supposed to be. However that only works in a war where you have ai…
Sure until they send 200 Shaheds at a night. Another another 200 next night and so on.
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Honestly: don't know. My experiments never had a dependency on linearity.
To detect something, you at least need response that isn’t effectively zero at the relevant frequency. And bonus points for not having ludicrous amounts of jitter due to polling a sensor over a bus like I2C that is really not intended to collect high frequency, equally spaced samples.
Took some spectras from heat pumps, airplanes and a helicopter.
So the sensor isn't blind within this range.
If these Shahed drones have a propeller they should have a brutal signature between 0-250Hz as they are moving a lot of air. And if the engine speed of the Shahed stays constant it will be even easier to detect it ("Angry lawnmower sound".. but that's only the high frequency part of it). There are extremely sensitive differential pressure sensors (like SDP600-25Pa) available from Sensirion that aren't overly expensiv…
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Reusable interceptor has BOM of 3000$, 15000$ sales price. Wanted to start this project with an ex-colleague, but he bought old house and is stuck trying to make it livable. Anyone interested in cooperation? I am hardware and math guy.
maybe this is a stupid question but how could you possibly re-use a thing that explodes in use
Think of fighters going up to intercept bombing missions in wwii.
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To detect something, you at least need response that isn’t effectively zero at the relevant frequency. And bonus points for not having ludicrous amounts of jitter due to polling a sensor over a bus like I2C that is really not intended to collect high frequency, equally spaced samples.
It "looked good" for me up to 100Hz after Nyquist in the spectrum but didn't pull any precise data. Just created a 50Hz tone using my speakers which showed up in the spectrum afterwards as expected as basic verification Took some spectras from heat pumps, airplanes and a helicopter. So the sensor isn't blind within this range.
A long time ago I used a hot wire anemometer to measure flow up to several hundred Hz, but that was an expensive instrument being read by an expensive National Instruments acquisition platform. This is a cheap, self-contained device. Go Sensirion.
I wonder whether the frequency limit ends up being set by the ADC or the physical sensor. I’m also curious how the Sensirion sensor detects the sign of the pressure difference.
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A $100k interceptor to save a $10 million critical facility against a $10k Shahed is a bargain. You saved $9.9 million dollars. Interceptor economics makes more sense when you reason about the bigger picture. The point is to buy you time to remove the supply chain and the stocks so that you're not trading 1:1 forever. It's a stop-gap, or at least it's supposed to be. However that only works in a war where you have ai…
> A $100k interceptor to save a $10 million critical facility against a $10k Shahed is a bargain. You saved $9.9 million dollars. Sure until they send 200 Shaheds at a night. Another another 200 next night and so on.
If these Shahed drones have a propeller they should have a brutal signature between 0-250Hz as they are moving a lot of air. And if the engine speed of the Shahed stays constant it will be even easier to detect it ("Angry lawnmower sound".. but that's only the high frequency part of it). There are extremely sensitive differential pressure sensors (like SDP600-25Pa) available from Sensirion that aren't overly expensiv…
The equivalent noise density of the sdp600 is 10^-2 Pa/sqrt(Hz). While the noise density of a typical microphone is 10^-6 Pa/sqrt(Hz). At same 50hz low frequencies. So either you're full of shit and a high quality microphone is x10000 more sensitive than this sdp600 sensor, or I'm not understanding what you're saying.
That being said, most microphones are intended for audio and their amplifiers and readout circuitry are not optimized for very low frequencies. And the physical measurement devices don’t work down to DC. (If they did then the microphone wouldn’t work — the DC pressure is around 1 atm, which is some 12 orders of magnitude above the more quiet sounds the microphone is trying to detect.)
A device sold as a pressure sensor will be intended for use at or near 0 Hz and will work fine.
I assume the actual practical crossover is something like 0.1 - 10 Hz depending on the microphone. There’s an additional practical issue, though: the pressure sensor comes from the factory already calibrated for DC, whereas you may be on your own trying to get physical units out of a microphone much below 20Hz.
If you use a high end microphone intended for professional use with phantom power, you will also be fighting the power circuit and lower frequencies.
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Spam specifically means (at least originally) so much unwanted traffic that it overwhelms legitimate traffic. So can I see why that commenter might have considered it a contradiction to say "the majority being truthful" as a strategy to deal with spam. The name comes from a Monty Python sketch where "SPAM!" is being sung so loudly that it drowned out any other conservation.
> Spam specifically means (at least originally) so much unwanted traffic that it overwhelms legitimate traffic. I guess what today is more commonly known as DOS (or even DDOS sometimes, even if it isn't actually "distributed" per se, for some reason). I did know about the name since before, but not the original meaning, so cheers for the explanation :)
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I don't follow American politics that closely, but here in Europe, I don't remember ever seeing Merkel doing this: - https://i.haasie.com/KeO.mp4 Can you please provide videos of them doing the same gesture?