3Briefly Discuss the error compensation mechanisms ?
4What is the difference between diffraction and scattering ?
5In ………………, Signals above 30 MHz are transmitted and not reflected by ionosphere a. Line Of Sight propagationb. Sky wave propagationc. Ground wave propagationd. b and c
6…………is based on the fact that individual channels experience independent fading events. a. Reflectionb. Diffractionc. Scatteringd. Diversitye. Refraction
7……………… is the unwanted coupling between signal paths. a. Thermal noiseb. Impulse noisec. Intermodulation noised. Crosstalk
8……….. is a measure of the directionality of an antenna. a. Effective areab. carrier frequencyc. Antenna gaind. speed of light ( 3 x108 m/s)
9A high SNR means a. a high quality signal b A high SNR means a. a high quality signal b. low number of required intermediate repeaters c. high noise power d. a and b
10Shannon's result is that the maximum channel capacity but practically only much lower rates achieved asa. Shannon assumes thermal noise onlyb. Attenuation distortion or delay distortion not accounted forc. Lack of repeatersd. Shannon assumed low bandwidthe. a and b
11State true or false for the following statements and correct the false: Omnidirectional antennas Radiates power equally in all directions ( )Refraction occurs at the edge of an impenetrable body that is large compared to the wavelength of the radio wave. ( )
12What’s the parity bit?A parity bit appended to an array of binary digits to make the sum of all the binary digits, including the parity bit, always odd (odd parity) or always even (even parity).
13What is the CRC?The CRC is an error detecting code in which the code is the remainder resulting from dividing the bits to be checked by a predetermined binary number.
14Why would you expect aCRC to detect more errors than a parity bit? The CRC has more bits and therefore provides more redundancy. That is, it provides more information that can be used to detect errors.
15List three different ways in which the CRC algorithm can be described. Modulo 2 arithmetic, polynomials, and digital logic.
16State true or false for the following statements and correct the false: a. CRCis an error detection process used in wireless transmission(false) Correction:FECb. Cyclic Codeisdesignedto correct single bit errorsCorrection:Hamming Codec. Cyclic CodeCan be encoded and decoded usinglinear feedback shift registers (LFSRs)(True)d. CRCTakes fixed-length input (k) and producesfixed-length check code (n-k)but CyclicCodeaccepts arbitrary length input for fixed-length check code(false) Correction:Cyclic-CRCe. Forward error correction (FEC) encoder maps each k-bit block into an n-bit block codeword(true)