Frequency content of a signal and range of significant frequencies.
The spectrum shows how signal amplitude and phase are distributed over frequency. Bandwidth is the range containing most energy (e.g. 3-dB or 99% power). A fast-changing signal needs more bandwidth. Spectrum analysers and FFTs display it.
A voice call needs about 3.4 kHz bandwidth; FM radio ~200 kHz.
Spectrum and bandwidth describe where signal energy lies, which sets the rate, filter and channel that can carry it.
Frequency content of a signal and range of significant frequencies.
Spectrum and bandwidth describe where signal energy lies, which sets the rate, filter and channel that can carry it.
The range of frequencies that contains most of the signal's energy or that a system passes, often measured between half-power points.
A short time pulse has a broad spectrum, so it needs a channel that passes many frequencies to avoid distortion.
Typical applications include choosing an ADC rate for a signal with a specified bandwidth, setting the passband of an audio amplifier to cover speech and estimating the channel bandwidth needed for a data stream.
Study "Fourier transform properties" first (topic 15 of 101 in Signals, Control & Comms). It covers the groundwork this topic builds on.
Occupied bandwidth. Bandlimited signals. Time-bandwidth product.
A voice call needs about 3.4 kHz bandwidth; FM radio ~200 kHz.
The next topic is "Parseval's theorem", which builds directly on this one.
It is classed as Beginner in Signals, Control & Comms (topic 16 of 101). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.
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