Hello, everyone.
The ENCOR OCG goes pretty deep into Wireless and this is the final L1 topic that I have to cover 
In contrast, wireless LANs must carry data at high bit rates, requiring more bandwidth
for modulation. The end result is that the data being sent is spread out across a range of frequencies.This is known as spread spectrum. At the physical layer, modern wireless
LANs can be broken down into the following two common spread-spectrum categories:
â– Direct sequence spread spectrum (DSSS): Used in the 2.4 GHz band, where a
small number of fixed, wide channels support complex phase modulation schemes and
somewhat scalable data rates. Typically, the channels are wide enough to augment the
data by spreading it out and making it more resilient to disruption.
â– Orthogonal Frequency Division Multiplexing (OFDM): Used in the 2.4, 5, and
6 GHz bands, where a single 20 MHz channel contains data that is sent in parallel
over multiple frequencies. Each channel is divided into many subcarriers (also called
subchannels or tones); both phase and amplitude are modulated with quadrature
amplitude modulation (QAM) to move the most data efficiently
Unfortunately, I don’t think I understand anything mentioned here..
We have a whole frequency spectrum that ranges from things that we can see all the way to xRay and such. So what exactly then is this spread spectrum, then?
The spectrum of frequencies that WiFi uses, or? The DSSS and OFDM explanations are pretty complex too to be honest and then they also talk about… QAM without any further explanations.
Thank you.
David