The bandwidth of a signal is defined as the difference between the upper and lower frequencies of the signal. It represents the range of frequencies occupied by the signal and is measured in Hertz (Hz). Different types of signals have different bandwidths. For example, the bandwidth of a voice signal is 300-3400 Hz, while the bandwidth of a music signal is 20-15000 Hz. Bandwidth is calculated differently for analog and digital signals, with analog bandwidth based on frequency and digital bandwidth on bit rate.

1.  The bandwidth of a signal is defined as the difference between the upper and
lower frequencies of a signal generated. As seen from the above
representation, Bandwidth (B) of the signal is equal to the difference between
the higher frequency (fH) and the lower frequency (fL). It is measured in
terms of Hertz(Hz) i.e. the unit of frequency.
 Bandwidth can also be defined as the portion of the electromagnetic (EM) spectrum
occupied by the signal.
 It is also defined as the range of frequencies that the signal occupies.
Signal bandwidth
Type of the signal Frequency range (Hz) Bandwidth (Hz)
Voice (speech) 300-3400 3100
Music signal 20-15000 14,980
TV (picture) signal 0-5Mega 5 MHz
Digital data 300-3400 (using telephone line) 3100
Different types of signals have different bandwidth. Ex. Voice signal,
music signal, etc
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2. Bandwidth of analog and digital signals is calculated in
separate ways. In analog technology, the bandwidth is the
difference between the lowest and highest frequencies
that can pass through the channel. Analog signal
bandwidth is measured in terms of its frequency (Hz) but
digital signal bandwidth is measured in terms of bit rate
(bits per second, bps).
Signal bandwidth
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3. Channel bandwidth
Type of the channel Frequency range (Approx.)
Twisted pair 1MHz – 100 MHz)
Coaxial cable 0 – 750 MHz
Microwave 1 GHz-30 GHz
Satellite 1 GHz – 40 GHz
Fibre optics 180 THz – 330 THz
In terms of analog signal, bandwidth of the channel is the range of frequencies that the
channel can carry. In terms of digital signal, bandwidth of the channel is the maximum bit
rate supported by the channel. i.e. number of bits per second that the channel can carry.
The bandwidth of the medium should always be greater than the bandwidth of the signal to
be transmitted else loss of information takes place.
Different types of channels have different bandwidth. Ex. Twisted pair, coaxial cable, fibre
optics etc.
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4. Bit Rate
It is defined as no of bits transmitted or sent in one second. It is expressed in bits per
second.
Bit rate = 1/ Bit interval
Baud Rate
The baud rate is the rate at which information is transferred in a communication channel.
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