Signals

Jun 18, 2023

• Fourier Transform

1. Spectrum (频谱): This refers to the range of frequencies that a signal contains. In signal processing, the spectrum of a signal or sound provides a representation of which frequencies are present in the signal. In other words, it’s a breakdown of a signal into its frequency components.
2. Wavelength (波长): This is the spatial period of a wave, the distance over which the wave’s shape repeats. It is usually determined by considering the distance between consecutive points of the same phase, such as crests, troughs, or zero crossings, in a waveform. The standard unit for wavelength is the meter (m).

$$v = f \cdot \lambda$$

• $v$: speed
• $f$: freq
• $\lambda$: wavelength

• Energy of a signal: area under the squared magnitude of the signal
• Finite energy (non-zero)
• Finite duration
• Zero average power

• Power of a signal: average of the squared magnitude in the time domain
• Non-zero average power
• Periodic and continue indefinitely in time

$$10 \cdot \lg\left(\frac{S}{N}\right) (dB)$$

• Interrupt
• Trap
• Exception
• Linux