In this section, we will solve some problems on wireless channel noise based on the white noise model.Example Problem 1A white noise has a 2-sided power spectral density of 6 kW/MHz. It is passed through a low pass filter having a bandwidth of 1 kHz. Compute the output noise power.Solution ... Read More

What is Wireless Channel Noise?It is not possible to have any wireless communication system/link with absolutely zero noise level. Noise is additive and hence at the receiver, we have the signal that contains both the transmitted data and noise. The most commonly used noise model is the Additive White Gaussian Noise (AWGN). ... Read More

Let us look at some numerical on amplifiers to get a better grip of the theoretical understanding.The ratio of output to input voltage of an amplifier is 20. Compute the voltage gain.Solution − The voltage ratio is given as 20. We need to convert this linear ratio into logarithmic ratio to ... Read More

Function of AmplifiersAmplifiers boost up or amplify weak signals. Repeaters are good examples of amplifying devices. They are present in few to several numbers at intermediate points between the transmitter and receiver, depending on the actual distance between the two. Periodic amplification at intermediate stations between the transmitter and receiver ... Read More

Problem 1 on Power LevelFor a communication link, the received power level is measured as 5 dBm. What does this mean?Here, we have a positive ‘dBm’ and hence we can say that the received power level is greater than the reference power level which is 1 mW.$$5dBm=10log_{10}(\frac{P_{received}}{1mW})$$$$log_{10}(\frac{P_{received}}{1mW})=\frac{5}{10}=0.5$$$$(\frac{P_{received}}{1mW})=10^{0.5}=3.1622$$$$P_{received}=3.1622mW$$We can infer that ... Read More

In wireless communication, the magnitudes of certain parameters such as power and voltage vary over several orders- for example; the received signal power level in mobile communications can vary between tenths of a milli-watt to about a few hundred of a milli-watt. For certain wireless communication systems, the received power ... Read More

dBW, dBV, dBmW, dBµW, dBmV and dBµVLet us see some commonly used decibel based representation units in wireless communications. The difference between these entities lies in the type of ratio and the reference levels of the quantities. We can have power ratio, voltage ratio, current ratio, and so on. Reference ... Read More

Valid and Invalid Operations on dBSome of the valid operations that can be performed with ‘dB' is discussed in this article. When we add ‘dB’ to a quantity, we are increasing its value and when we are subtracting ‘dB’ from a quantity, we are reducing its value.We can add ‘dB’ ... Read More

Introduction to dB OperationsThe ‘decibel’ is a form of representing ratios on a logarithmic scale instead of linear scale. They are used across several disciplines of STEM. In this article, we will see how to perform calculations using decibels with examples pertaining to electrical engineering. We know that the ‘decibel’ ... Read More

What are the applications of decibel (dB) representations?For convenient representation of data for analysis, the decibel representation is used for various parameters such as amplifier gain, return loss, path loss, signal-to-noise ratio (SNR) and so on. Some of such representations are presented here.Quantity in decibel (dB) = log10(Compared Quantity)/(Reference Quantity)Amplifier ... Read More