This is what it sounds like when you toss a quarter in front of an HB100. https://www.youtube.com/watch?v=8riretP8ylE
The bowtie looking part is the actual flight, the other part right after that is it bouncing off the counter.
Spinning same quarter - https://www.youtube.com/watch?v=5lnYvJoxRak
Shining it at parts of a ceiling fan - https://www.youtube.com/watch?v=tIiFvByf1CQ
which you can pretty much read as "for example, [example(s)]"
Commonly confused with i.e. (id est), which trasnslates to ‘that is’. The mnemonic there for me is ‘in other words’.
I ended up finding a program some college researcher had published for matching DNA patterns, and between a little data massaging and software hacking, I was amazed when results actually made sense.
As an intern, I never knew exactly who provided that CD or where the program went from there, but it was a fun problem to work on for a while.
One note, though. The presentation of IQ demodulation seems to mix up the real and imaginary components of the analytic signal with the electric and magnetic fields. Even if you skip the analytic signal and just generate a straight up real signal (with zero imaginary component), there will still be a magnetic field.
This seems important because the current presentation suggests the complex signal representation is somehow specific to electromagnetic signals, while it is really just a mathematical convenience applicable to any signal (EM, sound, wave on jump rope, etc).
Might be interesting too.
How exactly is this process "weaponisation"?
I'm having to translate it from TeX, so I don't know, but you might want The Scientist and Engineer's Guide to
Digital Signal Processing
By Steven W. Smith.
Shouldn't the received pulse have the same number of cycles as the transmit pules, and the received pulse be shorter than the transmit pulse (or longer in the case of the target moving away instead of toward the source)?
Or does something non-intuitive happen (probably because of special relativity) resulting in the received pulse gaining energy from the reflection, which is reflected (pun intended) as the pulse being longer than you'd expect classically?
Regarding the question, it is true that the received pulse will be shorter or longer than the transmitted one (depending on whether the object is moving towards or away from the sensor) but since we are assuming that the speed of the object is significantly less than the speed of light, we're making the simplifying assumption that this difference is negligible. People sometimes refer to this as the "stop and hop" assumption since in practice we are assuming that the object "stops" at point x when the radio wave is emitted and then "hops" to x + dt*v once the wave has been received dt seconds later.
Regarding the number of cycles, you are again correct that the image represents a gross oversimplification. One reason for this is that since the carrier frequency is so much higher than the doppler frequency, the true graph of the received wave would not be noticeably different than the transmitted one. It is easier to plot a realistic graph of the demodulated wave which you can see in the plot titles "samples of the demodulated pulse".
But the physics of it? That's something that seems entirely more complex to me.
Is it really? Could any of you explain how you emit the radio wave, and how you detect it back? In terms of hardware?
The alternating current is then feed down a transmission line, which in the most basic case is just 2 wires side by side. Being side-by-side, the current going "up" in one wire is balanced by the current coming "down" in the other so that at a distance from the transmission line, the radiation from the two wires (mostly) cancel each other out. Often instead of side-by-side, one wire is often wrapped around the other with an insulator separating them (coax), but the same principal applies.
The transmission line then feeds into the antenna. A basic antenna is a piece of wire exactly 1/2 wavelength long. Electric pulses "bounce" off the wire's ends, sort of like how if you tether one end of a rope and then shake the other, the "waves" going down the rope will "bounce". The length of the wire being 1/2 wavelength is key because it takes a wave exactly one cycle to start from one end, bounce off the other, and return to the start. Just as the first wave is bouncing off the start end, it gets a new "bump" from the transmission line. This allows a lot of current to build up in the antenna, sort of like how a kid on a swing can use several small well timed kicks to swing himself much higher than just a single big one could. Of course, antennas can be much more complicated than just a dipole, for example, you could place several dipoles in a row and feed them in phase so that their transmitted signals add together at points perpendicular to the row, and cancel each other at points in line with the row. Or, you could use a parabolic dish to concentrate the signals in one direction.
In radar, the radio waves travel out, bounce off objects in the their path, and a small fraction of the original signal comes back to the antenna. Depending on the design the radar might have a separate receiving antenna, or it might receive on the same antenna it used for transmitting. From a radio perspective, a receiving antenna is exactly the same as a transmitting antenna, only, it's the radio waves coming in through space that cause it to resonate instead of the other way around in a transmitting antenna.
Finally, the signal comes down the transmission line and into a receiver circuit which analyzes and extracts whatever data (in the radar case, it deduces distance and speed by looking at the elapsed time and frequency shifts).
Antenna's are generally resonant structures that are designed to inflict that on electrons. And thus are able to efficiently convert electrical energy to radio waves and back. Works both ways.
 If the cross product is zero radiation is also zero. Which is why most random metal structures suck ass as antenna's.
 Being resonant is not a requirement. Non resonant antenna's work but aren't as efficient.
the same antenna, if attached to an amplifier instead of an oscillator, will receive said radio-waves.
i'm obviously glossing over enough detail to fill several library shelves worth of books.
If this interests you I recommend reading some electrodynmics books (A challenging but fascinating subject!)
Otherwise I'd think you'd see a lot of radar dector jammers on the market.
https://youtu.be/vQtLms02PFM : popped out today on my YouTube feed, pretty relevant to this whole discussion (and also really worth talk)
Two typos in this sentence: One way to work around this problem is to use a non uniform spaceing of the pulses which is none as staggering. (spacing, known)
One way to work around this problem is to use a non-uniform spacing of the pulses, which is called staggering.