Recent questions tagged advanced-communication-system

Description : Describe the antenna subsystem of satellite. 

Last Answer : Antennas on the satellite serve as an interface between the earth stations on the ground and various satellite subsystems during operations Antennas receive the uplink signals and transmit the downlink ... Types of antenna system use in satellite communication:  Parabolic antenna 

Description : Draw the diagram of Fusion Splice and rigid alignment tube splice. 

Last Answer : Different types of splicing are: 1. Fusion splicing or welding 2. Mechanical splicing 3. Elastic tube splicing FUSION SPLICING: A fiber join is a type of wield. The fiber ends ... figure below is a unique device that automatically performs lateral, longitudinal and angular alignment. 

Description : Describe with the neat sketch of hybrid junction and illustrate its properties.

Last Answer : The magic tee is a combination of E and H plane tees. Arm 3 forms an H-plane tee with arms 1 and 2. Arm 4 forms an E-plane tee with arms 1 and 2. Arms 1 and 2 are sometimes called the ... are fed in through ports 1 and 2, they are added at the H-plane port and subtracted at the E-plane port.

Description : Draw the construction of Avalanche photodiode. State its working principle.

Last Answer : Avalanche photodiode are used to obtain the large gain, i.e. large output because Conventional photodiodes and PIN photodiodes obtain the limited gain. CONSTRUCTION: APD's are usually variation ... in avalanche with the number of carriers growing exponentially as the process continues.  

Description : Write up-link and down-link frequency for c-band, x-band, ka-band &ku-band.

Last Answer : Write up-link and down-link frequency for c-band, x-band, ka-band &ku-band.

Description : Draw the constructions of Gunn diode and explain its working.

Last Answer : Construction: When a dc bias of value equal or more than the threshold field (of about 3.3kV/cm) is applied to an n-type GaAs sample, the charge densities and electric field within ... device. The fundamental frequency in MHz is given by:   drift velocity and L=device length in µm. 

Description : Describe the working of directional coupler with neat diagram. 

Last Answer : Directional couplers are devices that will pass signal across one path while passing a much smaller signal along another path.  One of the most common uses of the directional coupler is to ... . The frequency determines the separation of the two holes as a fraction of the wavelength.  

Description : Explain with neat sketch block diagram of optical fiber communication system and list out sources and detectors suitable for it.

Last Answer : OR 1. The light source is normally an infrared LED or LASER device which is driven by the current value from the V to I convertor. It emits light which is proportional ... optical energy electrical signal. The light detectors which are used as PIN photodiode and avalanche photo diode.

Description : Explain the working of MTI radar with the help of block diagram and with suitable waveforms.

Last Answer : Explanation : The echo pulse from the target is received by MTI radar antenna. If echo is due to moving target, the echo pulse undergoes a Doppler frequency. The received echo pulses then pass ... for fixed target magnitude and polarity of output will remain the same as shown in figure.

Description : Illustrate how telemetry tracking and command system used in satellite communication.

Last Answer : Telemetry, Tracking and Command (TT&C) Subsystem These systems are partly on the satellite and partly at the control earth station. They support the functions of the spacecraft management. Telemetry System ... pulse to the satellite. Then the satellite executes these commands.   OR  

Description : Write radar range equation and state the factor affecting maximum range of radar.

Last Answer : The Radar range equation is given by The factors influencing maximum range are as follows Transmitted power (Pt): if the radar range is to be doubled we have to increase a ... (Pmin): A decrease in minimum receivable power will have the same effect has raising the transmuting power.

Description : Draw the construction of magnetron and describe it’s working.

Last Answer : Working/Operation: 1. Now assume RF oscillations are initiated due to some noise transient within the magnetron, the oscillations will be sustained by device operation. 2. Self- ... these favored electrons imparts enough energy to the RF oscillations so that they are sustained.  

Description : Draw the field pattern of circular waveguide for its dominant mode.

Last Answer : TE1,1 Mode is the dominant mode in circular waveguides. In TEm,n/ TMm,nthe letter m denotes the number of full-wave intensity variations around the circumference and n represents the number of half-wave ... changes radially out from the center to the wall. (Cylindrical co-ordinates are used).

Description : Draw block diagram of OTDR and explain its working.

Last Answer : Block diagram of OTDR Working principle of OTDR: A light pulse is launched into the fiber in the forward direction from an injection laser using either a ... backscattered light is detected using avalanche photodiode receiver. Output of photodiode receiver drivers an integrator.

Description : Define geo-stationary orbit and the geo-stationary satellite.

Last Answer : Geostationary Orbit: A geostationary orbit, geostationary Earth orbit is a circular geosynchronous orbit 35,786 kilometers (22,236 mi) above the Earth's equator. Geostationary satellite: A geostationary ... such a satellite appears nearly stationary in the sky as seen by a ground-based observer

Description : State two advantages and two applications of continuous wave radar.

Last Answer : Advantages of CW RADAR. (1) Capable of giving accurate measurement of relative velocity. (2) Low transmitting powers. (3) Compact hence can be used for mobile applications like police radar. (4) ... of the relative velocity of a moving target. (7) Human Gait Recognition (8) In Doppler Radar

Description : Sketch the construction of tunnel diode and write its operation.

Last Answer : Construction: Applications: • In digital networks. • As a high speed switch. • As a high frequency oscillator. • As a logic memory storage device. • In relaxation oscillator circuits.

Description : Compare between waveguide and two wire transmission line

Last Answer :  waveguide and two wire transmission line

Description : Distinguish between LED & LASER.

Last Answer : LED & LASER.

Description : Explain advantages of satellite communication system.

Last Answer : Broadcast property - Wide coverage area. Satellites, by virtue of their very nature, are an ideal means of transmitting information over vast geographical areas. This broadcasting property ... building and maintaining a communication facility is directly proportional to the distances involved.

Description : Explain absorption loss and scattering loss occurs in optical fiber.

Last Answer : Scattering loss:- Basically, scattering losses are caused by the interaction of light with density fluctuations within a fiber. Density changes are produced when optical fibers are manufactured.  ... glass material. iii. Intrinsic absorption by the basic constituent atoms of the fiber material.

Description : Describe the operation for pulsed radar to detect the object.

Last Answer : The Block diagram of high power Pulsed RADAR set is shown in fig. Above. Trigger Source: It Provides pulses for the modulator. Pulse Modulator: This Modulator provides rectangular ... . Sync pulses are applied by the trigger source to the display devices or the display indicator. 

Description : Describe working of Reflex Klystron amplifier with a neat diagram.

Last Answer : Operation: It is assumed that the oscillations are set up in the tube initially due to noise or switching transients and these oscillations are sustained by device operation. ... on the reference electron. These bunch transfer maximum energy to the gap to get sustained oscillations.

Description : State the advantages of circular waveguide and list its applications. 

Last Answer : Advantages:  The circular waveguide are easier to manufacture than rectangular waveguides and are easier to join. The TM01 modes are rotationally symmetrical and hence rotation of polarization can ... waveguides are also used with the cavity resonators to carry the input and output signals.

Description : With suitable sketch and explain the working of IMPATT diode.

Last Answer : Any device which exhibits negative resistance for dc will also exhibit for ac i.e. if an ac voltage is applied current will rise when voltage falls at an ac rate. Hence negative resistance can ... due to applied reverse bias at a drift velocity dependent upon the presence of high dc field.

Description : Describe rectangular waveguide in TE & TM mode.

Last Answer : i. Mode is defined as all possible configuration of electric and magnetic field which can exists in the waveguide. ii. Modes in rectangular waveguides are labeled TEm,nif they are transverse ... exist in rectangular waveguides. The formula for characteristic wave impedance for TM modes is,

Description : Define the following terms with respect to satellite: (i) Azimuth Angle (ii) Elevation Angle

Last Answer : Angle of Elevation: It is the angle subtended between the line of sight joining the earth station antenna and the satellite and the horizontal plane. Azimuth Angle: The angle measured ... (sub-satellite point) on the horizontal plane at the earth station is called as azimuth.

Description : List different display methods used in Radar. Explain any one display method.

Last Answer : Display methods used in RADAR are given below. 1. A-Scope 2. PPI 3. Automatic target detection A scope:   This is the most popular type of the deflection modulation type ... in the true bearing mode) or ship's heading (when the indicator is operated in the relative bearing mode) 

Description : Define the term w.r.t. waveguide: (i) Cut-OFF frequency (ii) Group Velocity

Last Answer : Group velocity: It is defined as the rate at which the wave propagates through the waveguide and is given by The group velocity is also can be defined as the velocity of energy flow ... rectangular waveguide at a frequency below fc TE1,0. This is absolute cut off frequency of the waveguide.