Electrical Engineering

An overhead power line is a structure used in electric power transmission and distribution to transmit electrical energy along large distances. It consists of one or more conductors (commonly multiples of three) suspended by towers or poles. Since most of the insulation is provided by air, overhead power lines are generally the lowest-cost method of power transmission for large quantities of electric energy. Towers for support of the lines are made of wood (as-grown or laminated), steel (either lattice structures or tubular poles), concrete, aluminum, and occasionally reinforced plastics. The bare wire conductors on the line are generally made of aluminum (either plain or reinforced with steel, or composite materials such as carbon and glass fiber), though some copper wires are used in medium-voltage distribution and low-voltage connections to customer premises. A major goal of overhead power line design is to maintain adequate clearance between energized conductors and...

Without communication systems there would be no mobile phones, internet, TV or radio. Communication systems are vital to our modern society for business, personal life, entertainment and leisure. Many of us could not imagine life without such commodities. On this course you’ll gain a hands-on introduction to communications and cover a range of topics such as analogue, digital and programmable electronics. Download

In this section we will look at the process of converting an analog signal to be digitally transmitted into a digital format. To transmit digitally we only have a discrete set of symbols that can be sent at a fixed rate. Hence before we can send the signal we need to quantize it in time and amplitude. A process of achieving this quantization is PCM. A general criterion is that the digitally modulated transmitted signal can be demodulated and converted back into an analog form with a tolerable amount of distortion. Generally the specification of“tolerable” is very subjective.For example consider voice quality requirements of a wireless phone. Given distortion tolerance, the objective is generally to optimize the encoding such that a minimum bit rate is consumed with the application.

Introduction Pulse modulation includes many different methods of converting information into pulse form for transferring pulses from a source to a destination. The four dominant methods are: 1. Pulse Amplitude Modulation (PAM) 2. Pulse Width Modulation (PWM) 3. Pulse Position Modulation (PAM) 4. Pulse Code Modulation (PCM) Pulse Amplitude Modulation   Pulse-amplitude modulation, also called PAM, is a form of signal modulation where the signal is encoded in the amplitude of a series of signal pulses. Example: A two-bit modulator (PAM-4) will take two bits at a time and will map the signal amplitude to one of four possible levels, for example −2 volts, −1 volt, 1 volt, and 2 volts. It is widely used in base band transmission of digital data

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1. GAIN STABILITY   The negative feedback amplifier increases the Gain Stability. ie; The gain will be stable over external or internal variations.  2. NOISE REDUCTION It is impossible to construct an Amplifier without NOISE. By using Negative Feedback amplifier we can reduce the Noise.  3. REDUCTION IN NONLINEAR DISTORTION   By the increase in Number of Amplifier stages, Nonlinear Distortion also increases Gradually. 4. BANDWIDTH CAN BE INCREASED Negative Feedback Amplifier Decreases the Voltage Gain, the reduction in voltage gain results improved Frequency Band Width. 5. INCREASE IN INPUT IMPEDANCE   The amplifier with Negative feedback Increases the Input impudence. Thus we can avoid loading of signal source.   6. DECREASE IN OUTPUT IMPEDANCE The amplifier with Negative feedback Reduces the output Impedance.