Skip to content
HomeVideosBooksBlogs
AllTop postsTopics
Podcasts
HistoryListsWatch laterLiked videosFollowing

The videos, books, blogs and podcasts Hacker News keeps recommending, all in one place.

VideosBooksBlogsPodcastsAboutPrivacySettings

Data from Hacker News, HackerTube, HackerBooks, HackerBlogs and Open Library. Credits · Not affiliated with Y Combinator.

HomeVideosBooksBlogsPodcasts
Ctrl K
    T

    Tim Wescott

    wescottdesign.com · Personal blog · on HN since 2014

    Tim Wescott, a control systems and embedded engineer, publishes articles on PID control and sampling theory.

    Visit blogHN submissions
    Hardware & ElectronicsMath
    What HN says

    Commenters recommend "PID Without a PhD" as an excellent, intuitive go-to reference for PID tuning. His sampling article is debated in Nyquist threads.

    Stats for nerds
    17HN people shared it
    5linked in comments
    1Kstory points
    Jun 2026last shared
    2014people per year2026

    Top posts on HN

    1. 1
      PID Without a PhD (2016) [pdf]
      9 people · 827 points · first shared 2018 · 114 comments on HN
    2. 2
      Sampling: What Nyquist didn't say, and what to do about it (2018) [pdf]
      8 people · 195 points · first shared 2014 · 74 comments on HN
    3. 3
      Articles
      1 person · first shared 2020

    What HN people wrote when they linked it

    • msandfordSep 2015

      http://parlos.tamu.edu/MEEN651/E4.pdf

      Read page 3. It completely validates what I'm saying. Monty might be a really smart guy, and he might be worthy of lots of praise for a great many things. But in this particular very limited instance, he is not as correct as he could be.

      If all you can do is link me to the Wikipedia page about this, you're way out of your depth. I took multiple classes on this in college and I raised exactly this issue with my professors. They said that technically I was right, but in practice nobody samples at exactly the Nyquist rate (or even that close to it!) and it's really more of a guideline for the slowest sample rate you could possibly get away with, not the sample rate you should pick once you know your frequency content. Both Shannon and Nyquist were very smart and they've made a gigantic contribution to DSP. But knowing the phrases "Nyquist rate" and "2x the highest frequency" doesn't a signal processing expert make.

      You can read plenty more here too if you'd like to get more educated. http://www.wescottdesign.com/articles/Sampling/sampling.pdf

      Here's a snippet:
      "The theme of this paper can be summed up to this: the Nyquist rate isn’t a line in the sand
      that you can toe up to with complete safety. It is more like an electric fence or a hot poker;
      something that won’t hurt you if you keep your distance, but never something you want to
      saunter up to and lean against."

      I totally understand if you just want to argue on the internet…

    • mutagenDec 2014

      I don't see how either of these papers solidly refute "because Nyquist" in the context of the article and sample rates applied to audio signals. They're both worth considering, though.

      The first[1], the more theoretical of the two, is focused on digital communications where a Nyquist rate derived from the signal rate isn't enough to recover the signal function. The numerical examples given highlight recovering a sine wave from two, three, and six samples. The millions of samples in a single song might as well be infinite compared to these.

      The second paper is much more practical and gives a number of real-world examples where naively applying Nyquist causes problems. The first, cutoff filters at half Nyquist to avoid aliasing, plauged many early CD players and other digital audio equipment. The second example is great as well, showing how understanding the signal being measured is important. The third example doesn't really apply to the subject at hand but is a good example of using aliasing for good. The fourth and fifth address the effect filters have on the signal. The sixth example refers to time response in control systems and minimizing phase delay to avoid oscillations.

      [1]http://www.academia.edu/8412078/Is_The_Nyquist_Rate_Enough
      [2]http://www.wescottdesign.com/articles/Sampling/sampling.pdf

    • ImageXavNov 2024

      I think it is you who have misunderstood the Nyquist-Shannon theorem. Aliasing and noise are real concerns. Tim Wescott explains it very well [0] (Figures 3, 10 and 11). If your signal is below one half the sample rate but the noise isn't, you'll lose information about the signal. If your signal phase is shifted wrt. the sampling, you'll lose information. If your sampling period isn't representative, you'll lose information. These are not implementation details.

      [0] https://www.wescottdesign.com/articles/Sampling/sampling.pdf

    • TylerEDec 2014

      What's so funny is to see yet another occurrence of basically "because Nyquist" yet fails to address that Nyquist only holds true over infinite time. Over a window of any finite length perfect reproduction is NOT guaranteed.

      This paper, http://www.academia.edu/8412078/Is_The_Nyquist_Rate_Enough, for one, refutes this.

      More reading material:

      http://www.wescottdesign.com/articles/Sampling/sampling.pdf

    • Greek0May 2020

      PID Without a PhD [1] is an excellent paper that gives a good intuition for PID controllers. In addition, it has concrete advice on how to go about implementing a practical control scheme, and how to tune the PID constants.

      It's really my go-to reference for any practical control theory application.

      [1]: https://www.wescottdesign.com/articles/pid/pidWithoutAPhd.pdf

    • wrigbyMay 2020

      Love this! I had read another paper from Wescott about sampling[1] years ago and loved it, but I didn't realize there's a handful of other great articles[2] that they've published.

      1: https://www.wescottdesign.com/articles/Sampling/sampling.pdf

      2: https://www.wescottdesign.com/articles.html

    Related

    Hackster.io Blogblog.hackster.io63 people

    New Hardware from PINE64

    Hackster.io Blog
    Company · last shared 2019
    David Robinsonvarianceexplained.org47 people

    One Year as a Data Scientist at Stack Overflow

    David Robinson
    Personal · last shared 2026
    The Morning Paperblog.acolyer.org606 people

    Local-first software: you own your data, in spite of the cloud

    The Morning Paper
    Personal · last shared 2026
    Tim Kadlectimkadlec.com65 people

    Is Apple stifling progress in Web standards?

    Tim Kadlec
    Personal · last shared 2023
    Wolfram Blogblog.wolfram.com225 people

    The solution of the Zodiac killer’s 340-character cipher

    Wolfram Blog
    Company · last shared 2026
    Gödel's Lost Letterrjlipton.wordpress.com185 people

    Mihai Pătraşcu 1982–2012

    Gödel's Lost Letter
    Personal · last shared 2021
    Extreme Learningextremelearning.com.au35 people

    The Unreasonable Effectiveness of Quasirandom Sequences

    Extreme Learning
    Personal · last shared 2026
    Statistical Modeling, Causal Inference, and Social Sciencestatmodeling.stat.columbia.edu350 people

    Suspicious data pattern in recent Venezuelan election

    Statistical Modeling, Causal Inference, and Social Science
    Publication · last shared 2026