Howtosignalprocessing
- What is a band-limited signal?
- What do you mean by band-limited and time limited signal?
- What are examples of band-limited signals?
- Why a signal cannot be both time limited and band-limited?
What is a band-limited signal?
A signal is said to be band-limited if the amplitude of its spectrum goes to zero for all frequencies beyond some threshold called the cutoff frequency.
What do you mean by band-limited and time limited signal?
In signal processing, there is a time-frequency duality. Band-limited signals have infinite time duration and time-limited signals have infinite bandwidth.
What are examples of band-limited signals?
Examples of narrowband signals may be found in a broad area of wireless applications, e.g., communications, radars, positioning, sensing, and remote control. Since energy of the narrowband signal is concentrated around ω0, its major performance is the envelope, phase, or/and instantaneous fre- quency.
Why a signal cannot be both time limited and band-limited?
A law of Fourier transformations says that if a signal is finite in time, its spectrum extends to infinite frequency, and if its bandwidth is finite, its duration is infinite in time. Clearly we cannot have a time-domain signal of infinite duration, so we can never have a truly band-limited signal.
