## What is Decibel Representation for Wireless Communications?

Updated on 23-Jun-2021 14:10:26
1. What is dB Representation?‘Decibel’ is a very common representation used across several disciplines of STEM (Science, Technology, Engineering and Mathematics). An electronic engineering student might have never missed coming across the terms‘amplifier gain’, signal-tonoise ratio’, ‘antenna gain’, ‘return loss’, ‘path loss, and so on. One thing common in all of them is that they are all expressed in ‘decibels’(dB). The decibel representation (dB) is to express magnitudes that vary over large range of levels, in a single plot.2. What is the Definition of decibel (dB)?The dB representation maps the ratio of two comparable quantities in the linear scale onto ... Read More

## What factors affect Latency and Jitter in Wireless Communications?

Updated on 23-Jun-2021 14:07:34
Latency is common in both wired and wireless systems. It is a quality of service (QoS) parameter – it acts as one of the performances determining factors of the wired or wireless communication link of interest. Different applications require different levels of latency. In simpler terms, latency refers to how quick the data is transferred from the source (or the sender) to the destination (or the receiver). Latency takes the unit of time. Link speeds are often specified in milliseconds (ms), microseconds (µs), nanoseconds (ns) and so on.Latency Is a Quality-of-Service ParameterNumeric example of latencyLet us look into an example ... Read More

## What is Modulation in Wireless Communications?

Updated on 23-Jun-2021 14:06:04
Overview of Modulation in Wireless CommunicationsLike bidding in auction, telecom service providers also auction frequency bands. Huge investments are made while bidding even smaller bands- say a few megahertz. Bands in the very basic sense mean the 'air' around us. Air is a wireless ‘channel’/ ‘transmission medium’ that carries our data confined the electric and magnetic fields of the electromagnetic waves.Therefore, bands mean the frequency ranges over which each service provider renders services to its subscribers. Since a huge amount of money is invested, effective utilization needs to be ensured. Technically, we need to use 'effective modulation techniques' for this ... Read More

## How are Spectrum and Bandwidth defined in Wireless Communications?

Updated on 23-Jun-2021 14:04:37
Definition of spectrumSpectrum refers to the entire range of frequencies right from the starting frequency (the lowest frequency) to the ending frequency (the highest frequency). Spectrum basically refers to the entire group of frequencies.Example of spectrum- Electromagnetic SpectrumThe electromagnetic spectrum is one good example. The electromagnetic (EM) spectrum covers frequencies right from zero (DC) to gamma band frequencies. This spectrum includes the human voice frequency band (audio band), ISM (Industrial Scientific Medical) band and optical frequency bands.Numeric example- Microwave radiation spectrumMicrowave radiations span in frequency from 300 MHz to 300 GHz. What is the spectrum of microwave radiation?Spectrum refers to ... Read More

## How Do You Define Bandwidth and Throughput in Wireless Communications?

Updated on 23-Jun-2021 14:03:32
A wireless communication link is specified or characterized in terms of some performance metrics. We call these performance metrics as 'Quality of Service' (QoS) metrics or parameters. Some of the major QoS parameters include bandwidth, throughput, jitter, latency and bit error rate.Bandwidth and Throughput – Key TermsBandwidth is a popular term used in the context of both networking and communications. In networking, the bandwidth is specified using bps (bits per second), kbps (kilobits per second), Mbps (Megabits per second) and so on.In communications, bandwidth is measured in the unit kHz (kilo Hertz), MHz (Mega Hertz), GHz (Giga Hertz) and so ... Read More

## Thevenin’s Theorem and Thevenin Equivalent Circuit

Updated on 18-Jun-2021 13:08:38
Thevenin’s Theorem is used, where it is desired to determine the current through or voltage across any one circuit element without going through the complex method of solving a set of network equations.Statement of Thevenin’s TheoremAny two terminal bilateral linear dc circuit can be replaced by an equivalent circuit consisting of voltage source in series with a resistance, the voltage source being the open circuited voltage across the open circuited load terminals and the resistance being the internal resistance of the source network looking through the open circuited load terminals.Explanation of Thevenin’s TheoremStep 1 – Remove the load resistor (RL) ... Read More

## Source Transformation with Solved Examples

Updated on 18-Jun-2021 13:07:22
A practical voltage source consists of an ideal voltage source in series with an internal resistance (for an ideal voltage source, this internal resistance being zero, so that the output voltage becomes independent of the load current) While a practical current source consists of an ideal current source in parallel with an internal resistance (for an ideal current source, this parallel resistance is infinity).The practical voltage and current sources are mutually transferable i.e. a practical voltage source can be converted into a practical current source and vice-versa.Voltage to Current Source TransformationConsider a practical voltage of V volts having a series ... Read More

## Series RLC Circuit: Analysis and Example Problems

Updated on 18-Jun-2021 12:52:04
Consider the circuit consisting of R, L and C connected in series across a supply voltage of V (RMS) volts. The resulting current I (RMS) is flowing in the circuit. Since the R, L and C are connected in series, thus current is same through all the three elements. For the convenience of the analysis, the current can be taken as reference phasor. Therefore, $$\mathrm{Voltage\:acorss\:\mathit{R}, \mathit{V}_{R}=\mathit{IR}}$$$$\mathrm{Voltage\:acorss\:\mathit{L}, \mathit{V}_{L}=\mathit{IX}_{L}}$$$$\mathrm{Voltage\:acorss\:\mathit{C}, \mathit{V}_{C}=\mathit{IX}_{c}}$$Where, XL = jωL = Inductive Reactince,  Xc = 1/jωC = Capacitive reactance. VR  is in phase with I. VL  is leading the current I by 90°. VC  is lagging the I by 90°.The total voltage ... Read More

## Series-Parallel Circuit: Definition and Examples

Updated on 18-Jun-2021 12:47:21
A series-parallel circuitis a combination of series and parallel circuits. In this circuit some of the elements are connected in series fashion and some are in parallel.In the circuit shown below, we can see that resistors R2 and R3 are connected in parallel with each other and that both are connected in series with R1.To solve such circuits, first reduce the parallel branches to an equivalent series branch and then solve the circuit as a simple series circuit.Here, RP is equivalent resistance of parallel combination given by, $$\mathrm{\mathit{R}_{p}=\frac{\mathit{R}_{2}\mathit{R}_{3}}{\mathit{R}_{2}+\mathit{R}_{3}}}$$Total circuit resistance (RT) is given by, $$\mathrm{\mathit{R}_{r}=\mathit{R}_{1}+\mathit{R}_{p}=\mathit{R}_{1}+\frac{\mathit{R}_{2}\mathit{R}_{3}}{\mathit{R}_{2}+\mathit{R}_{3}}}$$Voltage across the parallel combination is ... Read More

## Resistors in Series

Updated on 18-Jun-2021 12:45:19
The resistors are said to be connected in series, when they are joined end to end so that there is only one path for the current to flow.ExplanationLet the three pure resistors R1, R2 and R3 be connected in series against a DC voltage source V as shown in the circuit.Referring the circuit it can be written that$$\mathrm{\mathit{V}\:=\:\mathit{V}_{1}+\mathit{V}_{2}+\mathit{V}_{3}\:\:\:\:…(1)}$$Where V1, V2 and V3 being the voltage drops against individual resistors.Assuming I to be the total current in the circuit and R being the equivalent resistance of all the series resistors. Hence, the equation (1) can be written as$$\mathrm{\mathit{IR}=\mathit{IR}_{1}+\mathit{IR}_{2}+\mathit{IR}_{3}}$$$$\mathrm{\Rightarrow\:\mathit{R}=\mathit{R}_{1}+\mathit{R}_{2}+\mathit{R}_{3}\:\:\:\:…(2)}$$Thus, the equation (2) ... Read More