Bandwidth is the width or space that is available for transmission of the amount of data through it
Narrowband: means its bandwidth is much smaller ( by a factor of 10 or more) when compared with median frequency otherwise it is called a Wideband
Bandlimited: the signal is bandlimited when its spectrum is zero outside its frequency range
An analog to understand bandwidth
Consider road as a channel, and vehicles as data the wider the road the more vehicle can pass through it
The same analogy applies to bandwidth the wider the bandwidth the larger the amount of data can be transferred or pass through it, the narrower the bandwidth more congested will the channel and data congestion will lead to network slow down
How to measure Bandwidth?
Example: suppose a periodic signal is decomposed into four sine waves with frequencies of 100,400,600,800 then what is a bandwidth of a signal?
Let Bw be the required bandwidth, be the highest frequency and be the lowest frequency
Bw = = 800-100 =700 Hz
Drawing the spectrum which has only four spikes at 100,400,600,800