A data communication signal is any modulated electromagnetic wave or digital pulse over which data is transmitted from one location to another in a network. This signal is composed of two basic parts, baseband signal (information) and the carrier signal, which are mixed with each other through the process of modulation.
By Cisco Eng. Shingie Lev Muringi
Signals in data communications are generated by electronic communication devices, and are able to travel over wired and wireless media in order to reach their desired location.
These signals have some basic and measurable characteristics associated with them, which are also known as their intrinsic features.
Amplitude of a data signal is also known as its height or magnitude. This is the most basic and inherent characteristic of any data signal employed in communications and usually represents the strength of a transmitted signal.
Measurement of signal amplitude is usually carried out in the units of voltage (V) and current (I), and its calculation procedures differ in analog and digital data communication methods. Any comms signal travels through oscillating in the form of waves, and this oscillation is kept continuous in analog communication, such as land-line telephone systems and discrete in digital communications, such as computer and cellular networks.
Frequency is the number of cycles the data signal completes in the form of oscillation in a single second. It is another basic characteristic of a communication signal and represents the intensity of transmission and reception in data communication networks.
Frequency is strictly measured in Hertz (Hz) and calculated by the reciprocal of time period in seconds into which one oscillation or cycle is performed by the data signal. This value is directly proportional to the amount of data carried by the signal in a communications network.
Wavelength is the length of a signal, which is measured in meters (m). It is also the basic characteristic of a data signal, which is usually calculated by finding a ratio between the speed of light (c) and the frequency of the signal (f) as ‘c/f’.
The inclusion of the speed of light (300,000,000 meters per second) in the formula is made to show the velocity of a data signal, which is almost equal to that of light waves. Wavelength of a data signal is usually represented by the lambda sign (λ).
The phase of a data signal is the shift of its amplitude angles, which is commonly measured in degrees. In more precise terms, this quantity represents the changes that occur within the magnitude of a data signal cycles with respect to time.
This characteristic of the data signal is an important factor when two signals interfere with each other, because they can cancel each other out if their respective phases are opposite. The phase of a data signal is usually represented by the Greek letter ‘theta’ (θ) and in some places as Greek letter ‘phi’.