Hacker News Reader

belzebalexon Phased Array Microphone (2023)

A nice mention about this is the outstanding and quiet work of the Cosys-Lab of the University of Antwerp. They once put a microphone array below a scorpio, and showed how bats moved their ultrasonic beam to scan for a scorpio. Incredible stuff [0].

[0]: https://www.youtube.com/watch?v=57ScSPWhGqU

belzebalexon Phased Array Microphone (2023)

1) and 3) are valid, but 2) isn't really. In that sort of pipeline, you usually do IQ sampling which allows you to phase-shift by any arbitrary value with a complex multiplication.

belzebalexon Apple's AirPods Pro hearing health features

The main reason is that it's tough to have a uniform sound pressure distribution on a stage. That means the people at the front usually have very high sound levels, while those at the back have way lower. Technicians then make the tradeoff of having too high pressures at the front (where you must have earplugs) to afford to have medium levels at the back.

belzebalexon Ribbonfarm Is Retiring

This is quite sad, I've been very inspired by the writings of Artem Litvinovich [1] (although he stopped publishing 8 years ago). I inspired a lot of my research on what he did.

https://www.ribbonfarm.com/author/artem/

belzebalexon Homemade 6 GHz pulse compression radar

This is incredible.

I've wanted to thank the author for a while for his past articles [1][2] which have been a wonderful source of information when working on my sonar systems [3]. This article again explains really well a complicated topic. Please, keep up the great work!

[1]: https://hforsten.com/radar-phase-measurements.html

[2]: https://hforsten.com/6-ghz-frequency-modulated-radar.html

[3]: https://twitter.com/alextoussss/status/1756371553460121766

belzebalexon SymPy: Symbolic Mathematics in Python

I tried to use SymPy for a similar problem: computing the Jacobian of a complicated integral using quaternion rotations.

Problem was that the symbolic results were way too complicated and the simplify function didn't help much. So, I got back to manual differentiation.

belzebalexon Ask HN: Who wants to be hired? (February 2024)

  Role: Six-month intern/fixed term job March-September 2024
  Location: Anywhere in the world (on-site), willing to relocate
  Skills: 

    * Digital signal processing, machine learning, computer vision, control theory, electronics, electrical engineering
    * C/C++/Assembly, Python, Go, Javascript, Django, React, Docker, OpenGL, OpenCV ...
    * High-speed pcb design, FPGA programming,

Hey! I’m Alex Toussaint, an engineering student at CentraleSupélec (France). I’m currently working on drone navigation algorithms, and I’m looking for a full-time second six month internship abroad in robotics/computer science.

I’ve been passionate about technology and robotics for as long as I can remember! Here are a few things I worked on:

- Co-founded, built and sold a no-code crypto trading bot editor startup when I was in high-school (kaktana.com)

- Built an ultrasonic 3d scanner that works in the air capable of scanning in 3D a 140deg*140deg*8meters volume at 60fps[1] [2]

- Built my own high-performance quadcopter flight controller pcb and code from scratch.

See my GitHub [3] and resume [4][5] above for more! I’m looking for a fast-paced environment and don’t mind working on very hard technical projects.

[1]: https://news.ycombinator.com/item?id=27090795

[2]: https://www.alextoussaint.com/2021-04-28_How-I-built-an-ultr...

[3]: https://github.com/alextousss

[4]: https://alextoussaint.com

[5]: https://alextoussaint.com/resumev2.pdf

belzebalexon PID Controllers in Unity3D (2021)

One method that solves 99% of your control problems is the Ziegler-Nichols method [1]. It's a shame it's not taught more often.

No need to model your system, just increase the P gain until the system oscillates naturally. Measure the oscillation period, and then refer to the tables at [1] to choose the P, I, D gains depending on how you like your system response to look like.

[1]: https://en.wikipedia.org/wiki/Ziegler%E2%80%93Nichols_method

belzebalexon PID Controllers in Unity3D (2021)

Yes it does, you have to manipulate the expression to make it adimensional. But this rule-of-thumb is only valid for systems whose response time is less than 500ms.

belzebalexon Ask HN: Who is looking for a cofounder?

I'm working on a 3d sonar to replace costly lidars.

Already have a state-of-the art prototype that has better performance than $3k lidars for under a hundred bucks.

Applications are robots that need to navigate autonomously in a non-cooperative environment (humanoid robots, delivery drones, etc). There's also a dozen other applications to use the sensor for (indoor millimeter-localization with beacons, insect detection and identification, passive localization of sound sources, etc).

I'd love to meet someone with a strong technical background but who could help me on all non-technical tasks (getting funding, finding an application to focus on, managing certifications, etc)

More context at [1] [2]

I'm currently based in France but would like to relocate in March when I finish my current internship.

[1]: https://www.alextoussaint.com/2021-04-28_How-I-built-an-ultr...

[2]: https://www.alextoussaint.com/

alex at alextoussaint.com

belzebalexon Ask HN: Who wants to be hired? (January 2024)

  Role: Six-month intern/fixed term job March-September 2024
  Location: Anywhere in the world (on-site), willing to relocate
  Skills: 

    * Digital signal processing, machine learning, computer vision, control theory, electronics, electrical engineering
    * C/C++/Assembly, Python, Go, Javascript, Django, React, Docker, OpenGL, OpenCV ...
    * High-speed pcb design, FPGA programming,

I’ve been passionate about technology and robotics for as long as I can remember! Here are a few things I worked on:

- Co-founded, built and sold a no-code crypto trading bot editor startup when I was in high-school (kaktana.com)

- Built an ultrasonic 3d scanner that works in the air capable of scanning in 3D a 140deg*140deg*8meters volume at 60fps[1] [2]

- Built my own high-performance quadcopter flight controller pcb and code from scratch.

See my GitHub [3] and resume [4][5] above for more! I’m looking for a fast-paced environment and don’t mind working on very hard technical projects.

[1]: https://news.ycombinator.com/item?id=27090795

[2]: https://www.alextoussaint.com/2021-04-28_How-I-built-an-ultr...

[3]: https://github.com/alextousss

[4]: https://alextoussaint.com

[5]: https://alextoussaint.com/resumev2.pdf

belzebalexon Ask HN: What side projects landed you a job?

Got my first internship building drone navigation systems after building my own quadcopter flight control board (software included) (https://github.com/alextousss/quadcopter)

By the way, looking for a second one March-September 2024 :)

belzebalexon Ask HN: Who wants to be hired? (December 2023)

  Role: Six-month intern/fixed term job March-September 2024
  Location: Anywhere in the world (on-site), willing to relocate
  Skills: 

    * Digital signal processing, machine learning, computer vision, control theory, electronics, electrical engineering
    * C/C++/Assembly, Python, Go, Javascript, Django, React, Docker, OpenGL, OpenCV ...
    * High-speed pcb design, FPGA programming,

I’ve been passionate about technology and robotics for as long as I can remember! Here are a few things I worked on:

- Co-founded, built and sold a WYSIWYG crypto bot editor startup when I was in high-school (kaktana.com)

- Built an ultrasonic 3d scanner that works in the air capable of scanning in 3D a 140deg*140deg*8meters volume at 60fps[1] [2]

- Built my own high-performance quadcopter flight controller pcb and code from scratch.

See my GitHub [3] and resume [4][5] above for more! I’m looking for a fast-paced environment and don’t mind working on very hard technical projects.

[1]: https://news.ycombinator.com/item?id=27090795

[2]: https://www.alextoussaint.com/2021-04-28_How-I-built-an-ultr...

[3]: https://github.com/alextousss

[4]: https://alextoussaint.com

[5]: https://alextoussaint.com/resumev2.pdf

belzebalexon FPGA Dev Boards for $150 or Less

I'm surprised this does not include the excellent Alchitry boards [1] which are quite cheap and capable ($100 for an Artix-7 35T dev board is a steal)

[1]: https://www.sparkfun.com/categories/tags/alchitry

belzebalexon Ask HN: Who wants to be hired? (November 2023)

  Location: USA/out of France Internship
  Willing to relocate: Yes, from France
  Technologies: C, C++, Python, Javascript, Django, React, Verilog, Arduino, STM32, ...
  Résumé/CV: alextoussaint.com/resumev2.pdf
  Email: alex@alextoussaint.com
  Website: alextoussaint.com
  Dates: Available full-time from March to August 2024

Gap-Year student at CentraleSupélec (France) looking for a six month internship abroad in robotics/computer science.

Notable achievements:

- Co-founded kaktana.com when I was in high-school (cryptocurrency trading bot WYSIWYG editor, one of the most complete on the market, sold 3 years later)

- Created one of the first ultrasonic 3d scanners that works in the air [1] [2]

- Created a custom real-time acoustic camera using a microphone phased array (FPGA/Verilog)

[1]: https://news.ycombinator.com/item?id=27090795

[2]: https://www.alextoussaint.com/2021-04-28_How-I-built-an-ultr...

belzebalexon Ask HN: Who wants to be hired? (October 2023)

  Location: USA/out of France Internship
  Willing to relocate: Yes, from France
  Technologies: C, C++, Python, Javascript, Django, React, Verilog, Arduino, STM32, ...
  Résumé/CV: alextoussaint.com/resume.pdf
  Email: alex@alextoussaint.com
  Website: alextoussaint.com
  Dates: Available full-time from February to August 2024

21yo Master of Science student at CentraleSupélec (France) looking for a six month internship abroad in robotics/computer science.

Notable achievements:

- Co-founded kaktana.com when I was in high-school (cryptocurrency trading bot WYSIWYG editor, one of the most complete on the market, sold 3 years later)

- Created one of the first ultrasonic 3d scanners that works in the air [1] [2]

- Created a custom real-time acoustic camera using a microphone phased array (FPGA/Verilog)

[1]: https://news.ycombinator.com/item?id=27090795

[2]: https://www.alextoussaint.com/2021-04-28_How-I-built-an-ultr...

belzebalexon Ask HN: Who wants to be hired? (September 2023)

  Location: USA/out of France Internship
  Willing to relocate: Yes, from France
  Technologies: C, C++, Python, Javascript, Django, React, Verilog, Arduino, STM32, ...
  Résumé/CV: alextoussaint.com/resume.pdf
  Email: alex@alextoussaint.com
  Website: alextoussaint.com
  Dates: Available full-time from February to August 2024

21yo Master of Science student at CentraleSupélec (France) looking for a six month internship abroad in robotics/computer science.

Notable achievements:

- Co-founded kaktana.com when I was in high-school (cryptocurrency trading bot WYSIWYG editor, one of the most complete on the market, sold 3 years later)

- Created one of the first ultrasonic 3d scanners that works in the air [1] [2]

- Created a custom real-time acoustic camera using a microphone phased array (FPGA/Verilog)

[1]: https://news.ycombinator.com/item?id=27090795

[2]: https://www.alextoussaint.com/2021-04-28_How-I-built-an-ultr...

belzebalexon Ask HN: Most interesting tech you built for just yourself?

Built one of the first 3d ultrasonic scanner that works in the air to make an autonomous drone [1] [2]

[1]: https://www.alextoussaint.com/2021-04-28_How-I-built-an-ultr...

[2]: https://hackaday.com/2021/05/15/a-phased-array-ultrasonic-3d...

belzebalexon Ask HN: Who wants to be hired? (January 2023)

  Location: USA/out of France Internship
  Willing to relocate: Yes, from France
  Technologies: C, C++, Python, Javascript, Django, React, VHDL, Arduino, STM32, ...
  Résumé/CV: alextoussaint.com/resume.pdf
  Email: alex@alextoussaint.com
  Website: alextoussaint.com
  Dates: Available full-time from July to December 2023

20yo French looking for an internship abroad involving robotics or computer science in general.

Notable achievements:

- Co-founded kaktana.com when I was in high-school (cryptocurrency trading bot WYSIWYG editor, one of the most complete on the market, sold 3 years later)

- Created one of the first ultrasonic 3d scanners that works in the air [1] [2]

[1]: https://news.ycombinator.com/item?id=27090795 [2]: https://www.alextoussaint.com/2021-04-28_How-I-built-an-ultr...

belzebalexon Evidence that life flashes before the eyes upon death

How did it end?

belzebalexon China bans for-profit school tutoring in sweeping overhaul

I think your analysis is great, but a better solution might be to just pay and consider teachers better.

Here's a data point: in France, after high school, we're put for two years into a "preparatory class" where we prepare during two years for engineering school entrance exams. Preparatory class selection occurs on high school achievements but don't matter at all: the teaching is roughly the same between the preparatory schools. And, teachers in preparatory schools are usually the best you can find: they're very well paid and hugely respected. Plus, they have to pass an exam where they are filtered on their teaching capabilities. In my two years there, I've had very good teachers. The curiculuum is very intensive. The normal workday is 8am-6pm of regular classes and extends until sleep for most students. It is rough, but long enough so that the only way to survive is to keep a healthy work-life balance. I didn't work a lot during holidays, slept for 9 hours every night and kept partying most weekends but still managed to get into France's second best engineering school. And, private teachers don't help much. The state already employs the best teachers you can find and there's so much school time that it would be hard to find time for private lessons. Furthermore, exams are made in a way that is very hard to game. I still think the best way to go into an elite engineering school is to be genuinely interested in engineering, maths and physics.

belzebalexon Stress does turn hair gray, and it’s reversible

Was badly stressed preparing for the entrance exam for engineering schools. It was to the point I had heart palpitations for hours.

Two things made it disappear: - Sport, even just running an hour a week stopped the palpitations - Magnesium supplements

It's bearable for me because it won't last more than two years. Over the long-term, I would suggest trying to fix the problem from the inside (therapy? meditation? switching jobs?).

belzebalexon Tesla no longer accepts Bitcoin due to climate impact

You're completely right. I think the second order effects are negligible at this scale.

belzebalexon How I built the world's first 3D ultrasonic scanner

Not at all! There are many "Ecole Normale" which are just schools for teachers. The "Superieure" refers to the fact that you have to pass a hard exam to get in. And once there you can do research or become a teacher in a preparatory school (which prepares you to do the ENS's exams, in a pyramidal way)

belzebalexon How I built the world's first 3D ultrasonic scanner

Author here, the title is a bit misleading. In the article, I specify that it's the first 3d ultrasonic scanner (of my knowledge) that works in the air.

belzebalexon How I built the world's first 3D ultrasonic scanner

I'm in France ;-)

belzebalexon How I built the world's first 3D ultrasonic scanner

Would you have any links please? I didn't see any that did small development batches for a price lower than 200 EUR.

belzebalexon How I built the world's first 3D ultrasonic scanner

I definitely would like an English translation. Though, from what I understand (the diagram and the translation of the title) it's a graphic input device that can work out a few points at the time, and not in the same sphere (as echos will overlap, a point I develop in my article).

So it's not properly able to scan an object like I did?

Apart from that, how have you found that untranslated 1975 Russian patent? Google Scholar?

It's impressive what they were able to build with such low-tech.

belzebalexon How I built the world's first 3D ultrasonic scanner

It is exactly what it is, except I used ultrasounds (40khz, easy to work with) instead of electromagnetic waves.

belzebalexon How I built the world's first 3D ultrasonic scanner

That's smart. Didn't think about it!

Though, the emitter is pulsed and I also rely on the fact that it stops resonating after I cut out the power. Unless my LC oscillator has a low Q, it will keep oscillating after I cut out the supply, which is something I'd prefer to avoid.