Data Speed vs. Channel Bandwidth

This page describes the difference between Data Speed and Channel Bandwidth. In data communication, the amount of information that can be transmitted through a channel is proportional to the channel’s bandwidth.

For voice communication, approximately 3KHz of bandwidth is needed. Music, on the other hand, requires about 15 to 20KHz due to the higher frequencies and harmonics present. Television broadcasts demand even more bandwidth, typically around 4MHz.

The relationship between channel capacity and bandwidth can be expressed by the following formula:

C = 2B

Where:

• C is the channel capacity in bits per second (bps)
• B is the channel bandwidth in Hz

For systems that use multiple levels of modulation or encoding, the equation is modified as follows:

C = 2B log₂N

Where:

• N is the number of encoding levels per time interval.

Shannon-Hartley Theorem

In practical scenarios, every channel introduces some level of noise. This noise needs to be taken into account when calculating the channel capacity. The Shannon-Hartley theorem provides a more realistic calculation, incorporating the signal-to-noise ratio:

C = B log₂ (1 + S/N)

Where:

• C = Channel Capacity, bits/s
• B = Bandwidth in Hz
• S/N = Signal to Noise Power Ratio