For the past couple weeks, I have been wrestling with a question: To what are the waves compared when using OFDM and QAM? This took me on a long journey that ended in a simple question: nothing. Here is how I got there.
For those of you who are long time readers, you will remember when I talked about types of digital modulation. At the end of said blog, the additional reading lead to quadrature amplitude modulation. Recently, I was explaining phase shift keying to someone and got to thinking, “When using phase shift keying, the signal is compared to itself in the past.” (admittedly, I was wrong, but bear with me.) So how does an 802.11 radio compare all the subcarriers in an OFDM signal? And to what are they compared?! Continue reading “OFDM and You”