Noise & Interference
Shot Noise Waveform
This waveform represents shot noise, characterized by random noise spikes.
This kind of noise is more evident in low current and low-light conditions.
This graph depicts a 5 Hz sine wave (Original Signal) and its 3-bit quantized version (Quantized Signal). The difference between the original and quantized signals represents quantization noise.
Common Mode Noise
Differential Mode Mode Noise
Inter Symbol Interference
The top graph shows both the original pulses (solid lines) and their smeared counterparts (dashed lines) after passing through a communication channel, modeled as a first order low pass filter).
The bottom graph showsthe received signal, which is a superimposition of the individual smeared pulses. The red-shaded regions highlight where the smearing effect of one symbol extends into the time frame of the next symbol, causing ISI.
Note: For the example, we spaced out each bits to visually demonstrate the smearing effect into next symbol window. However in practice, the symbols are peseorandomly generated (i.e, 11011000. )
In essence, Welch's method allows us to examine the power of the signal in the frequency domain, providing a more comprehensive understanding of noise characteristics. Analyzing the signal in the Fourier domain is particularly useful because it helps isolate individual frequency components, making it easier to identify and mitigate sources of noise and interference.
An illustration demonstrating the impact of added noise levels on spectral esitimation is provided below: