Henrik Forstén

Previous discussion of a similar project, by [evidently] the same person: http://hforsten.com/6-ghz-frequency-modulated-radar.html

As before, this is totally awesome---until the FCC (or other national spectrum regulator) shows up at your door...

Here is an assortment of things that the author might be interfering with in the neighborhood of his 5.5 GHz carrier frequency: https://wirednot.wordpress.com/2014/01/07/what-else-is-in-the-5-ghz-spectrum-hint-its-not-just-weather-radar/

Some of this is the sort of stuff you really don't want to interfere with--both for safety reasons, and because of the likelihood of enforcement.

Next time I suggest that the author look into whether his jurisdiction will grant him an experimental license so he can do this legally. In many jurisdictions that is cheap and easy (unless, of course, you want to operate in a band where the interference risk is just too high).

Edit: I see the author is in Finland. Unfortunately for the author, I'm guessing this changes nothing since these frequencies are regulated both nationally and internationally. But it does mean that there is probably some local variation in the exact services that might be subject to interference. And who knows: maybe in Finland the 5.5 GHz band is a "do whatever you want at any power level you want" band. But I doubt it...

Absolutely not, unfortunately. One of the architectural issues plaguing even comparatively memory-safe languages is the fact that there is a global scope that's accessible from anywhere. In some Python versions even numbers or truth values could be redefined. [0]

This makes it impossible to sandbox functions or imported modules, because they can communicate arbitrarily. But communication/access security is not the only problem. Resource security is something I haven't seen any significant language (besides Java perhaps) try to approach - being able to limit the memory and cpu usage of a (part of a) program. Modern languages should make it possible to do both with just a few lines of code.

I recommend reading about Capability Security[1], the E language[2] and the Principle of least Authority (POLA) [3]

[0] https://hforsten.com/redefining-the-number-2-in-python.html

[1] http://www.cap-lore.com/CapTheory/

https://en.m.wikipedia.org/wiki/Capability-based_security

[2] http://www.erights.org/

[3] https://medium.com/agoric/pola-would-have-prevented-the-event-stream-incident-45653ecbda99

These originated in the mainframe era, in a connected world before the internet, at the inception of the first multi-user systems: https://github.com/void4/notes/issues/41

The radio waves are collected at points and don't have any x or y data, so making an image out of it is pretty challenging and usually requires moving the radar beam. He just kept the beam still, so the only things you can really see are things that move.

In the image, the bottom axis is distance(calculated from the time the reflection took/the frequency output by the mixer), the color is the strength of the reflection, and the left axis is the time. He walked away from the setup and then back, visible as the two lines, which fade out almost completely as he changes direction, because he is far away and therefore looks smaller to the radar.

http://hforsten.com/static/img/fmcw/football_field_range.png

From this data you could theoretically build an image of his upper torso and head, but it would be very blurry. His arms and legs were not static, and the radar doesn't know how they were moving, so they would just show up as blurs.

I've been somewhat disappointed that the learning material around mimo radar processing that can be done with popular TI automotive radar chips (and others) is somewhat limited after you get through with the absolute basics.

TI's documents are a good starting point: https://training.ti.com/sites/default/files/docs/mmwaveSensing-FMCW-offlineviewing_0.pdf

But it doesn't really go into the different schemes for sending out orthogonal waveforms from the transmitters, the design of 2d arrays, much of the basic signal processing (windowing, matched filtering), etc.

I was pleased to see https://hforsten.com/mimo-radar-antenna-arrays.html pop up on hacker news quite a while ago, which was very interesting. Goes into how to plot the beam width for a mimo array, with some nice python code. I want more, but I'm afraid I won't get it unless I read through a phd thesis. Any ideas/tips?

DNA is not just a sequence that encodes proteins. We just found out there's a secondary higher level code in it:

https://news.ycombinator.com/item?id=6896779

And then there's RNA, which can fold and form structures, sort of like proteins.

Anybody who has ever seriously dealt with things produced by evolution knows that evolution "cheats" and optimizes when constrained by resources, producing structure upon structure upon structure, crazy indirection and non-obvious side-effects, as long as it helps the goal (survival and reproduction usually).

That's why I don't think human brains will be understood any time soon. We might figure out all the layers, but to figure out all the hidden structures would take a superhuman AI.

EDIT:

Example of circuit design by evolutionary algorithms:

http://hforsten.com/evolutionary-algorithms-and-analog-electronic-circuits.html

Newer version in this post - http://hforsten.com/third-version-of-homemade-6-ghz-fmcw-radar.html

An interesting application of CW radar - http://hforsten.com/heartbeat-detection-with-radar.html

At 45 years old I feel like I've learned quite a bit, but when I read stuff like this I wonder if there are enough years left in my life to learn what to takes to put something like this together.

I will say that the little CW doppler radar boards are fun to tinker with. You can get them on amazon for <$10 shipped, power them with 5 volts and just wire the output to a microphone jack.

https://www.amazon.com/SMAKN-Microwave-10-525GHz-Doppler-Detector/dp/B00FFW4AZ4

This is what a coin toss over a 10GHz doppler device sounds like: https://www.youtube.com/watch?v=8riretP8ylE