Found 1011 Articles for Digital Electronics

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 ensures that there is a desired level of signal-to-noise ratio (SNR) maintained with the signal to successfully complete the final mile of transmission.Understanding Amplifier GainsExample 1If in a two-amplifier system where the amplifiers are cascaded in series, the first amplifier provides a gain of 10 dB while the second amplifier ... 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 the received power level is 3.1622 times greater than the reference power level. However, this doesn’t mean that the received power level is greater than the input or transmitted power level. In fact, the received power level can never be greater than the transmitter power. In practice, the received power ... 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 can vary between a few tens of a watt up to few tenths of a microwatt! This is due to the wireless channel conditions in the form of noise, fading and so on.The following equations represent the voltage and power gains with reference to 1 V and 1 W respectively.$$Voltage\:gain(dBV)=20log_{10}(\frac{Voltage\:Value}{1V})$$$$Power\:gain(dBV)=10log_{10}(\frac{Power\:Value}{1W})$$Since ... 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 levels can be 1 W, 1 V, 1 mW (milli-watt), 1 mV (milli-volt), 1 µW (microwatt), 1 µV (microvolt), and so on.Voltage based dB representation unitsThe ratio of two voltages will be mapped on to the decibel scale. Often, one of the two quantities of the ratio is a 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’ to ‘dBm’ but not ‘dBm’ to ‘dBm’.37 dBW + 3 dB gives 40 dBW. However, 37 dBm + 37 dBm doesn’t yield 74 dBm. This is an invalid operation.$$37\:dBm=10log_{10}(\frac{P_{out}}{1mW})$$$$log_{10}(\frac{P_{out}}{1mW})=3.7;\:P_{out}\sim\:10^{3.7}mW\sim\:5W$$Also, 74 dBm ≈ 25 MW. When we add 37 dBm to 37 dBm, all we get is around 10 kW, which ... 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’ represents the ratio of two quantities on the logarithmic scale. While comparing two quantities, one of them will be considered as a reference. This article discusses the basic operations that could be performed on decibels with some examples.Basic operations based on logarithmsLogarithmic MultiplicationThe logarithm of the product of two numbers ... 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 GainRF (Radio Frequency) power amplifier gains are also usually expressed in ‘dB’. It is a practice to arrange amplifiers in series to achieve high gain at the output. This form of arrangement is called cascading. In a cascaded amplifier system, the output of one amplifier is fed as input to ... Read More

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

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

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