Since I have so much to do with the discrete Fourier transform (DFT) – both recently and not so recently – I always wanted to make a sort of “cheat sheet” about it with the most important relations of the various time and frequency dimensions and some of the more important transform pairs all on …
Monthly Archives: August 2010
Ampersand of the Day
Als ich neulich The Invention of Lying sah, ist mir dieses schicke Ampersand im Abspann aufgefallen: Die Schrift heißt Windsor Light Condensed, und wird auch gerne von Woody Allen benutzt, wie man hört.
Optical OFDM – Cyclic Prefix
One of the most common misunderstandings about OFDM that keeps coming in most discussions on the topic is if subchannels are still orthogonal when there is a cyclic prefix involved. But let’s start at the beginning… Dispersion We have seen in this post that the DFT can be used at the receiver to demultiplex the …
Cross-Channel Fiber Nonlinearities
In a recent discussion with Curtis Menyuk, Alexei Pilipetskii, and Chongjin Xie I was made aware of a slightly inexact statement in the JLT published last year in which I was a co-author. It concerned the separation of XPM and XPolM in the nonlinear phase evolution equation. Since we were writing about XPolM at the …