https://entron.github.io/Cheng Guo's Blog 2026-06-05T17:12:48+02:00 Cheng Guo https://entron.github.io/ Jekyll © 2026 Cheng Guo /assets/img/favicons/favicon.ico /assets/img/favicons/favicon-96x96.png 2026-05-27T14:00:00+02:00 2026-06-05T17:12:07+02:00 https://entron.github.io/posts/%E7%BF%A0%E5%A0%A4%E6%98%A5%E6%99%93-The-Great-Waltz/ Cheng Guo

最近看了一部1938年的黑白电影电影《翠堤春晓》（The Great Waltz）。 这部电影超出了我的预期。 从去年开始我特别着迷摄影摄像，所以这部电影的第一个镜头很快引起了我的注意。电影开始时，镜头先从二楼的栏杆拍起，然后慢慢向下移动，最后落到施特劳斯妻子身上。空间调度和视线引导，放在今天看也许不算什么，但是这部电影是90年前拍摄的，我还是很惊讶，那个时代的电影人已经开始有这样的思考了。 影片里面讲了约翰·施特劳斯、他的妻子，还有那个女歌唱家三个人的一些故事。这三个人都非常有特点。约翰·施特劳斯有天赋、有激情，也有追求。那个女歌唱家真诚地热爱音乐，也真诚地爱着施特劳斯，但在见到他的妻子之后，她最终选择了清醒而体面的退出。而约翰·施特劳斯的妻子是一位非常伟大的女性，她非常好地处理了这段关系，也给了约翰·施特劳斯工作上很大的支持。 我感觉电影的名字 The Great Walt...

2026-05-20T14:00:00+02:00 2026-05-20T14:00:00+02:00 https://entron.github.io/posts/The-Voyager-Mission/ Cheng Guo

I learned about @NASAVoyager when I was about 10, from old kids’ science magazines published around 1980, either 我们爱科学 or 少年科学画报. Those magazines were originally bought by my grandpa for my aunts when they were kids. I spent countless hours reading them and probably read each issue more than 50 times. I recently watched the BBC documentary The Farthest: Voyager’s Interstellar Journey, and all t...

2026-05-14T14:00:00+02:00 2026-05-19T22:14:11+02:00 https://entron.github.io/posts/Classical-Kalman-Filter-Is-Simple-and-Elegant/ Cheng Guo

Kalman filtering often looks intimidating at first. Many introductions start with matrix equations, state-space models, Gaussian distributions, and recursive Bayesian estimation. All of that is correct, but it can hide a very simple idea: A Kalman filter is a principled way to combine uncertain information. I am writing this to help myself, and hopefully my dear reader, quickly grasp the core...

2026-05-13T14:00:00+02:00 2026-05-13T14:00:00+02:00 https://entron.github.io/posts/Sound-direction-detection-with-ESP32-and-two-microphones/ Cheng Guo

I have just open-sourced my little sound direction detection project here: entron/esp32_sound_direction. The idea is simple: use an ESP32 and two microphones to estimate where a sound is coming from. We do this naturally with our two ears, and I wanted to see whether I could do the same thing with two microphones. It is not a lab-grade localization system. It is a practical hobby project th...

2026-05-03T00:00:00+02:00 2026-05-05T21:51:20+02:00 https://entron.github.io/posts/The-Humble-Antenna-Is-Not-So-Humble/ Cheng Guo

The following blog post is drafted by ChatGPT based on my discussion on this topic with some of my edits. I have been working on a small hobby robot whose goal is intentionally modest: place it in a room, and it should move toward the brightest area it can find. Actually 16 years ago I built such a robot with Lego. Now I want to build a “pro” version of it with STM32/ESP32. It does not nee...