Electric & electronics engineering

characteristics of an ideal op-amp (operational amplifier)

IDEAL op-amp

There are are many characters op-amp in the market right now. Every company designing their won design for work in new applications. Before a engineer make a design of an op-amp he need to know the IDEAL op-amp characteristics. characteristics of an ideal op-amp (operational amplifier): • Infinite Differential Gain • Zero Common Mode …

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what is Astable Monostable and Bistable in EEE

Figure 3: Basic animated interactive BJT bistable multivibrator circuit

what is Astable Monostable and Bistable in EEE In the EEE department, students need to know  what is Astable Monostable and Bistable. Basically this three mode are a type of multivibrator circuit. So we can say there are three types of multivibrator circuit. Astable Monostable Bistable Astable: in which the …

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A short description “TDMA definition and main features TDMA”

Definition of TDMA

A short description “TDMA definition and main features TDMA” Definition of TDMA: Time Division Multiple Access (TDMA) systems divide the radio spectrum into time slots and each time slot is assigned to only one user. In TDMA/TDD half of the time slots in the frame information message would be used …

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A short description of “FDMA definition and the main features of FDMA”

FDMA definition

A short description of “FDMA definition and the main features of FDMA” Definition of FDMA: Frequency Division Multiple Access (FDMA) assigns individual channels to individual users. Each user is allocated a unique frequency band or channel. These channels are assigned on demand to users. Main Features of FDMA: FDMA channel carries only one …

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A short description of “Duplexing, Frequency Division Duplexing, Time Division Duplexing”

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A short description of “Duplexing, Frequency Division Duplexing, Time Division Duplexing” Duplexing In wireless communication system, it is often desirable to allow the subscriber to send simultaneously information to the base station while receiving information from the base station. This effect is duplexing. Frequency Division Duplexing FDD provides two distinct bands of frequencies for …

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A short description of “Radio Wave Propagation”

A short description of Radio Wave Propagation

A short description of “Radio Wave Propagation” Radio waves propagate through space as travelling electromagnetic waves. The energy of signals exists in the form of electrical and magnetic fields. Both electrical and magnetic fields vary sinusoidally with time. The two fields always exist together because a change in electrical field generates a magnetic field …

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A short description of “Three Basic Propagation Mechanisms”

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A short description of “Three Basic Propagation Mechanisms” Basic propagation mechanisms – Reflection – Diffraction – Scattering Reflection occurs when a propagating electromagnetic wave impinges upon an object which has very large dimensions when compared to the wavelength, e.g., buildings, walls. Diffraction occurs when the radio path between the transmitter …

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A short description of “Signal Fading Statistics”

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A short description of “Signal Fading Statistics” The rapid variations (fast fading) in signal power caused by local multipaths are represented by Rayleigh distribution. The long-term variations in the mean level are denoted by lognormal distribution. With a LOS propagation path, the Rician distribution is often used for fast fading. Thus, the fading …

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A short description of “Characteristics of Wireless Channels”

Multipath Delay

Characteristics of Wireless Channels The wireless channel is different and much more unpredictable than the wireline channel because of factors such as multipath and shadow fading, Doppler shift, and time dispersion or delay spread. These factors are all related to variability introduced by mobility of the user and the wide …

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A short description of “Lee’s Path Loss and Prediction Model”

Lee’s Prediction Model copy

Lee’s Path Loss and Prediction Model Lee’s Path Loss: Lee’s model can be used to predict area-to-area path loss. The model consists of two parts, Path loss prediction for a specified set of conditions. Adjustment factors for a set of conditions different from the specified one. Lee’s Prediction Model: The model requires two …

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A short description of “walfisch-ikegami propagation model”

walfisch-ikegami propagation model

walfisch-ikegami propagation model The Walfish–Ikegami model is an empirical propagation model for an urban area, which is especially applicable for micro cells but can also be used for macro cells. Model Parameters: The mean value for street widths (w) is given in meters and the road orientation angle (θ or φ) in degrees. …

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A short description of “Cost 231 & Hata Model”

A short description of "Cost 231 & Hata Model"

Cost 231 & Hata Model This model is a combination of empirical and deterministic models for estimating the path loss in an urban area over the frequency range of 800 MHz to 2000 MHz. The model is used primarily in Europe for the GSM 1800 system. #Ref book: Wireless Communication and Networking – …

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A short description about “Hata and Okumura Model”

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Hata and Okumura Model Okumura analyzed path-loss characteristics based on a large amount of experimental data collected around Tokyo, Japan. He selected propagation path conditions and obtained the average path-loss curves under flat urban areas. Then he applied several correction factors for other propagation conditions, such as: Antenna height and carrier frequency Suburban, …

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