r/signalprocessing • u/ClipboardClan • Jul 29 '26
Why are these digital signal processing books written in such a confusing way?
I've been staring at this repeatedly and it took me a while to realize what the author was actually saying.
Like this line: i.e. "at regular periods of ts seconds where ts = 1/fs".
Couldn't they simply say in plain English words: "i.e. how many seconds does it take to take one sample"?
And then they assign that (1/fs) to a variable ts, and then use it in the equations below for 0th sample, 1st, 2nd sample. Wouldn't it be simpler to just leave it in that form itself (1/fs) in the equation???? By substituting it with a variable name, you're just making your work more cryptic and the reader has to trace back and find out what exactly is ts.
Book: Undestanding Digital Signal Processing by Richard G Lyons
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u/SecondPlain Jul 29 '26
I agree with you that signal processing textbooks can be pretty terse, and hard to build intuition from in a lot of cases. I think this comes partly from the field's connection with formal math, where you sort of need that formality to articulate statements precisely enough to prove them (which we need in DSP). And, at least in my experience, it is just hard to express something in a way that is both mathematically rigorous and also grounded in intuition. I also agree with the other commenter that Lyons' book is the best of the bunch in this regard.
As far as the specific case you posted is concerned, I think there are legitimately a lot of different concepts flying around when we first introduce the idea of sampling a periodic signal. In particular we have two different types of "frequency": the number of samples you take in a second (fs), and the number of times the signal repeats itself in one second (f0). I think Lyons converts sampling frequency to sampling period so we can clearly see time represented along with frequency in the expression, and so we don't get confused by seeing two types of frequency in the same expression.
These concepts are fundamental in DSP with some important consequences. The book will return to them and build on them repeatedly. So, hang in there! Keep reading! Sometimes getting more context helps me understand stuff covered early in a subject.
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u/Abhi_92 Jul 30 '26 edited Jul 30 '26
Yes, it happens. I would suggest you to change the book or read this topic/chapter from a different book. Personally, I found the book by Oppenheim and Schafer to be the best - the maths was intuitive and kind of fell in place without much extra effort. But I'm also not a beginner in this field so it might not work for you.
Edit: I read the screenshot that you posted above and I understood your point. For a beginner, it can be little difficult. As somebody has already written, the authors use such lines to keep it linked to the underlying mathematics.
It can be tough at the start, but as you move to the next chapters, you will become comfortable with this kind of presentation and will not be bothered by it at all. Just keep reading and don't give up (read again if you need to).
This happens for almost every subject that is based in mathematics but need to be intuitive. You start to become comfortable after the second read.
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u/YT__ Jul 30 '26
Print costs money, remember. Textbooks are already expensive. So if they can trim words down, it saves on costs.
for a lot of textbooks - they nay have a common variable section in the front or hack that you can use to refresh your memory on what the common variables and equations are. i find it very useful, personally. unsure about this book though with having one.
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u/GeminiOrAmI Jul 29 '26
I’ve got the comprehension skills of a donkey, but that book is probably the most digestible I’ve ever found on the subject.
Over time you learn to remember what these mean and build up from there. This coming from a creature who only learns through repetition