Advanced M-ary Communication Lab Analytical & Statistical Performance of Digital Modulation Theoretical Probability of Error (\(P_s\)) \[ P_s = Q\left(\sqrt{\frac{2 E_b}{N_0}}\right) \] Modulation (M-ary) BPSK (M=2) QPSK (M=4) 8-PSK (M=8) 16-QAM (M=16) 64-QAM (M=64) 256-QAM (M=256) SNR (\(E_b/N_0\)): 12 dB Efficiency 2 bps/Hz Min Dist (\(d_{min}\)) 1.41 Symbol Error 1.2e-5 EVM (RMS) 0.0% Constellation Diagram Noise PDF & Decision Tail 1. Geometric Mapping ...

87. Match the List-I with List-II. Breakdown Electric fields in the following materials: List-I (Name of the material) List-II (Breakdown Electric field (V/cm)) (a) GaAs I. 10 5 (b) SiC II. 4 × 10 5 (c) Si 3 N 4 III. 2.3 × 10 6 (d) Ge IV. 10 7 Choose the correct answer from the options given below: (a) (b) (c) (d) A. II III I IV B. II III IV I C. IV II III I D. IV I III II Answer: option B Previous yr Question papers with Full Explanations →

86. In case of Avalanche Photo Detector (APD) (a) APD is more sensitive than PIN photo diode (b) APD is a PIN structure (c) A high electric field intensity is required in APD (d) There is less noise generation in APD as compared to PIN photo diode A. (a) and (b) only B. (b) and (c) only C. (a) and (d) only D. (a) and (c) only Answer; Option D Previous yr Question papers with Full Explanations →

Function of LDR Function of an LDR (Light Dependent Resistor) An LDR (Light Dependent Resistor) is an electronic component whose resistance changes according to the amount of light falling on it . Function of an LDR In bright light: the resistance of the LDR becomes low. In darkness: the resistance of the LDR becomes high. This property allows an LDR to act as a light sensor . Common Applications Automatic street lights (turn on at night, off during the day) Light-sensitive alarms Camera light meters Solar garden lights Brightness control in electronic devices Working Principle An LDR is made from a photoconductive material (commonly cadmium sulfide). When light strikes the material, more charge carriers are generated, allowing current to flow more easily and reducing resistance. ...

85. Which of the following statements are correct? (a) Light Dependent Resistors (LDRs) are based on Photo conductive Effect. (b) In LDRs, resistance increases from its dark resistance value with increase in light intensity. (c) LDRs are slow responding to changes in light intensity. (d) Photodiodes can be operated only in the photoconductive region. (e) Photodiodes have a faster switching time than Photo-transistors. A. (a), (c) and (d) only B. (a), (b) and (c) only C. (a), (b) and (e) only D. (a), (c) and (e) only Answer: Option D Previous yr Question papers with Full Explanations →

83. The Doppler frequency seen by a stationary radar with a (CW) transmit frequency of 5 GHz and target radial velocity of 100 km/hr is: A. 387 Hz B. 256 Hz C. 428 Hz D. 927 Hz Answer Option D Solution doppler frequency = 2*v/λ =2*(100*5/18) / (3*10^8/5*10^9) = 927 (approx) Read more about Doppler Frequency (click here) Previous yr Question papers with Full Explanations →

82. Which of the following statements are correct when effective mass of an electron is taken into consideration: (a) The electron effective mass is independent of the semiconductor properties. (b) Electrons near top of the V.B. have negative effective mass (c) The C.B. electron effective mass has a strong dependence on the value of bandgap (d) The effective mass decreases as the bandgap increases. A. (a) and (c) only B. (a) and (d) only C. (b) and (c) only D. (b) and (d) only Answer: Option C Previous yr Question papers with Full Explanations →

81. Which of the following statements are correct about the basic transistor amplifier configuration? The voltage gain of CB amplifier is higher than the voltage gain of CC amplifier The CB amplifier has low input impedance and a low current gain The CC amplifier has high input impedance and a low current gain The CC amplifier has low output impedance and a high current gain The CC amplifier has low input impedance and a low current gain A. (a), (b) and (d) only B. (a), (b) and (c) only C. (a), (b) and (e) only D. (a) and (b) only Answer: Option A Previous yr Question papers with Full Explanations →