In this type of media, the signal propagates in the form of electromagnetic waves without the requirement of solid media, i.e., in the air. There are also called wireless media.The electromagnetic spectrum used for wireless communication is shown in the figure −Propagation MethodsThe unguided signals can travel from the transmitter to the receiver in many different ways. The three most important methods are −Ground Wave PropagationSKY PropagationSpace propagation or line of sight propagationBandsThe electromagnetic spectrum is divided into several subbands. The following table shows various frequency bands corresponding to multiple types of propagation and application −Electromagnetic Waves BandNameFrequencyWavelengthExtremely Low Frequency ... Read More

We are getting different types of services by using various modes of communication. The wired method of communication is one of the most efficient and successful modes. There are different types of cables available such as twisted pair cables, coaxial cables, and optical fiber cables. Read through this article to find out the characteristic features that differentiate these cables. What is a Twisted Pair Cable? A twisted pair cable comprises two insulated wires that have been twisted together. They are in use in the field of communications for a long time. You might have seen this type of cable ... Read More

A fibre optic cable is made of glass or plastic and transmits signals in the structure of light signals. The structure of an optical fibre cable is displayed in the figure. It involves an inner glass core surrounded by a glass cladding that reflects the light into the core. Each fibre is encircled by a plastic jacket.In fibre optics, semiconductor lasers transmit data in the form of light along with hair-thin glass (optical) fibres at the speed of light (186, 000 miles second) with no significant loss of intensity over very long distances. The system includes fibre optic cables that ... Read More

Co-axial includes a central copper wire surrounded by PVC insulation over which a copper mesh sleeve is placed. Again, the metal sleeve is shielded by an outer shield of thick PVC material, as shown in the figure.The coaxial cable structure provides it with the right mixture of high bandwidth and good noise community. For 1 km cables, a data price of 10 Mbps is feasible. Higher data rates are applicable for shorter cables. Co-axial cables are generally used for cable TV and long-distance transmission within the telephone system.Characteristics of Co-axial CableThe main characteristics of the coaxial cable are as follows ... Read More

Twisted-pair are generally made of copper, and a pair of wires are twisted together to decrease interference by adjacent wires. A twisted pair includes two conductors (copper), each with its plastic insulation, twisted together. One of the wires can transfer signals to the receiver, and the difference is used just as a ground reference. The receiver helps the difference between the two.This means, if two wires are correlated to each other, the noise or crosstalk can affect one wire, and the difference between the two levels would vary. When these wires are twisted, both wires have a similar effect of ... Read More

A transmission media can be represented as anything that can take data from a source to a destination. The transmission media function maintains the data in the form of bits through LAN (Local Area Network).In data communications, the definition of the data and the transmission medium is more precise. The transmission medium is generally free space (i.e., air), metallic cable or fiber-optic cable. The data is frequently a signal that is the result of a conversion of data from another form.Causes of Transmission ImpairmentNoise absorption is due to susceptibility leading to external electrical noise, distorting the data signal and data ... Read More

It is the description of analog data by an analog signal. Modulation of analog signals means converting analog signals to an analog signal. It is required because the sender’s signal is of low pass and can be of the same range. For example, each radio station has a low pass signal, which may be of the same range. Different stations signal to avoid intermixing; each low pass signal must be shifted to a diverse range on the frequency band.The diagram shows the relationship between the analog information, the analog-to-analog conversion hardware, and the resultant analog signal.Analog-to-Analog modulation can be achieved ... Read More

Phase Shift Keying (PSK) is limited by the equipment’s ability to distinguish the small phase difference. This factor is responsible for determining its potential bit rate. Quadrature amplitude modulation can be defined as a consolidation of ASK and PSK so that a maximum difference between each signal unit (bit, dibit, tribit, and so on) is accomplished.IN QAM, there are several possible variations. Suppose any measurable number of amplitude changes can be mixed with any measurable number of phase modifies. The figure shows 2 possible configurations, 4-QAM and 8-QAM.In both methods, the number of amplitude switch is less than the number ... Read More

In phase-shift keying (PSK), the carrier phase is different to describe binary 1 or 0. Both peak amplitude and frequency remain constant as the process modifies. For example, if we begin with 0 degrees to define binary 0, we can adjust the procedure to 180 degrees to transmit binary 1. During each bit duration, the signal phase is fixed, and its cost is based on the bit (0 or 1).The diagram shows a conceptual view of PSK −The following technique is known as 2-PSK, or binary PSK because two multiple procedures (0 and 180 degrees) are used. Figures make this ... Read More

In frequency-shift keying (FSK), the carrier signal frequency is varied to illustrate binary 1 or 0. The frequency of the signal during each bit period is constant, and its value based on the bit (0 or 1) both peak amplitude and phase remain constant.The figure provides the conceptual view of FSK −FSK prevents most of the noise issues of ASK. Because the receiving device considers definite frequency changes over a given number of time, it can neglect voltage spikes. The limiting aspects of FSK are the physical efficiency of the carrier.Bandwidth for FSKAlthough FSK changes between two carrier frequencies, it ... Read More