Bandwidth of Signals
Rate at which electronic signals can travel through a medium, such as a wire, cable, or channel.
Bandwidth may be thought of as the width of the 'pipe' through which data travels: greater the width, larger the amount of data that can flow through it.
Technically, it means the difference between two frequencies. In analog transmission (such as of voice signals over copper telephone lines).
The bandwidth is measured in cycles per second (or Hertz); for example, a telephone conversation requires about 4,000 Hertz (4KHz) of bandwidth.
Bandwidth is the difference between the upper and lower frequencies in a continuous set of frequencies. It is typically measured in hertz, and may sometimes refer to passband bandwidth, sometimes to baseband bandwidth, depending on context.
Passband bandwidth is the difference between the upper and lower cutoff frequencies,
for example, a band-pass filter, a communication channel, or a signal spectrum. In the case of a low-pass filter or baseband signal, the bandwidth is equal to its upper cutoff frequency.
Bandwidth in hertz is a central concept in many fields, including electronics, information theory, digital communications, radio communications, signal processing, and spectroscopy and is one of the determinants of the capacity of a given communication channel.
Bandwidth of Transmission Medium
Wires are the most commonly used transmission media. A wire offers a bandwidth of approx 750 MHz.
Wireless transmission over the air and free space range from a few hundred kHz to a few GHz.
The transmission over optical fiber can offer a signal bandwidth more than 100 GHz.
The bandwidths are allocated to radios, televisions and cellular communication companies by the government of the country.
Measurement of the Bandwidth of a Signal
Bandwidth describes the difference between upper and lower frequencies in transmission signals. The measurement of the bandwidth of a signal is done in hertz (Hz).
Depending on the context, the bandwidth may specifically be referred to passband bandwidth or base bandwidth.
Bandwidth also can be expressed as bytes per second. This is commonly denoted with a capital B. For example: 10 megabytes per second would be expressed as 10 MB/s or 10 MBps.
Relation between bandwidth and frequency
The main difference between bandwidth and frequency is that bandwidth measures the amount of data transferred per second in other hand the frequency measure the number of oscillation of the data signal per second.
Different types of signals and bandwidth
| Type of the signal | Bandwidth (Hz) | Frequency range (Hz) |
|---|---|---|
| Voice (Speech) | 3100 | 300-3400 |
| Music signal | 14,980 | 20-15000 |
| TV (picture) | 5 MHz | 0-5Mega |
| Digital data | 3100 | 300-3400 (using PSTN) |
| Type of the channel | Freq. range (Approx.) | |
|---|---|---|
| Twisted pair | 1MHz – 100 MHz | |
| Coaxial cable | 0 – 750 MHz | |
| Fibre optics | 180 THz – 330 THz | |
| Microwave | 1 GHz-30 GHz | |
| Satellite | 1 GHz – 40 GHz |