Digital Communication

Quiz Unit  4 Sampling SY L  Link to Quiz 1

Quiz Unit 1  Sampling TY L Aug - Dec 2017 Link to Quiz 1

Satellite Link Budget Q.1)  An earth station antenna has a diameter of 30m has an overall efficiency of 68% and is used to receive a signal at 4150MHz. At this frequency system noise temperature is 79K when antenna points at the satellite at the elevation angle of 28 0 . What is earth station G/T under these conditions? If heavy rain causes the sky temperature to increase so that the system noise temperature rises to 88K, what is the new G/T value? Q.2)  Define following terms                     i)   Kepler’s First Law                     ii)  Kepler’s Second Law                     iii) Geostationary Earth Orbit                     iv) Polar Orbit                     v) Low Earth Orbit Q.3)  At input of receiver received carrier power is 400pW and system noise temperature is 450K. Calculate carrier to noise ratio. For a bandwidth of 36MHz calculate carrier to noise density ratio in dBHz. Q.4)  A satellite freq of 11.7GHz is used by satellite locate

digital communication, digital communication assignment,  digital communication assignment no 4,  digital communication assignments,  digital communication all assignments Q.1) The information bit duration in DS-BPSK spread spectrum communication system is 4 ms while the chipping rate is 1 MHz. Assuming an average error probability of 10 –5 for proper defection of message signal, calculate the jamming margin. Interpret your result. Q.2) Develop a schematic for PN sequence to get maximum length of 255 states. Q.3) State and explain properties of PN sequence. Q.4) A PN sequence is generated using a feedback shift register of length m = 4 the chip rate is 107 chips per second. Find the following parameter : i) PN sequence length ii) Chip duration of the PN sequence iii) PN sequence period. Q.5) Develop maximal-length codes for the feedback configuration [6,5,3,2] whose period is 63 and initial seed is 100000 and verify sequence as PN sequence. Q.6)

Digital Modulation Techniques digital communication, digital communication assignment,  digital communication assignment no 2,  digital communication assignments,  digital communication all assignments Q.1) Draw & explain euclidian distance and PSD of BPSK, M-ary PSK & 16-ary QAM. Q.2)Explain QPSK. Elaborate your answer with suitable expression, signal space& spectral representation. How QPSK signal is generated and received? What is the difference between OQPSK & QPSK? Q.3) Error occurs in DPSK in pair & in DEPSK error always occurs in single bit. Explain with suitable example. Q.4) Describe the scheme to recover the baseband signal in BPSK. With the help of block diagram and signals marked at input, output of these blocks. Also show that output of receiver is proportional to square root of power within the bit duration. Q.5) Sketch the Power Spectral density of BPSK signal and estimate the bandwidth where input data rate is 10Mbps a

Digital Communication digital communication, digital communication assignment,  digital communication assignment no 3,  digital communication assignments,  digital communication all assignments Q.1 )  A baseband receiver has received signal amplitude ± 2V held for a time T. The signal is corrupted by white Gaussian noise having Power Spectral density 10 –4   volt 2 /Hz. If the signal is processed by integrate and dump filter, what should be minimum Time T of the signal so that the error probability is not above 10 –4 . Q.2) Binary data is transmitted using PSK at a rate 2 Mbps over RF link having  bandwidth 2 MHz. Find signal power required at receiver input so that error  probability is less than or equal to 10 –4 . Assume noise PSD to be 10 –10 watt/Hz.  Q.3) Prove that “The performance of integrator and dump filter is identical to that  of the matched filter on the background of AWGN”. Calculate the probability  of error Pe. Q.4) A bipolar binary si