The document discusses the differences between analog and digital signals. It notes that while analog signals seem better, digital signals are less impacted by noise. It provides an example where an analog signal of 2.5v is transmitted but the receiver detects 2.7v due to 0.2v of noise. However, in a digital system with set levels, the noise would be negligible and the accurate signal of 2.5v would be received. Digital signals are better for communication systems as they can minimize the effects of unwanted noise.