signal analysis

What is the mean of a signal?

Average value of the signal

What does variance measure?

Signal variability

What does standard deviation measure?

Spread of signal around mean

What does RMS represent?

Signal power (includes amplitude + variability)

What is correlation?

Measure of similarity between two signals

What is autocorrelation?

Signal compared with itself

What is cross-correlation?

Similarity between two signals with time shifts

What are orthogonal signals?

Signals with zero correlation

What is SNR?

Ratio of signal to noise

How is SNR improved?

Averaging

How does averaging affect noise?

Noise decreases by √N

What is ensemble averaging?

Averaging repeated signals to reduce noise

What is the Nyquist criterion?

fs ≥ 2 × fmax

What happens if Nyquist is violated?

Aliasing

What is aliasing?

High frequency appears as lower frequency

Formula for alias frequency?

f_alias = fs − f_signal

What does an ADC do?

Converts analog signal to digital

What is resolution in ADC?

Number of bits (precision of signal)

What does the frequency domain show?

Distribution of signal energy across frequencies

What is a spectrum?

Frequencies present in a signal

What does FFT do?

Converts time domain → frequency domain

What does magnitude spectrum show?

Strength of each frequency

What is a power spectrum?

Magnitude squared of FFT (|X(f)|²)

What information is lost in power spectrum?

Phase

What is Fourier series?

Representation of periodic signal as sum of sinusoids

What is Fourier transform?

Converts non-periodic signal to frequency domain

What are harmonics?

Multiples of fundamental frequenc