I need accurate answer without using automation tools or plagairised answers 265. How does quantization affect digital network performance?
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QUESTION 2 a) Describe briefly some advantages of digital over analog transmission. (2 marks) b) With the aid of diagrams describe the process of creating a PCM signal out of an analog waveform. (3 marks) c) Describe factors that can degrade the performance of a communication system. (2 marks) An analog signal is sampled at Nyquist rate and 5-bit PCM encoded using a bit interval of Tb=100μs. The PCM signal is received with a Peak S/N of 30 dB. d) Find the null bandwidth necessary for transmitting the PCM signal using Unipolar NRZ pulses. (2 marks) e) Find the null bandwidth necessary for transmitting the PCM signal using Manchester NRZ pulses. (2 marks) f) Compare Unipolar NRZ and Manchester NRZ line coding regarding bandwidth requirement, DC value and synchronization signal generation. (3 marks) g) Calculate the average noise power of the received PCM signal if the Peak signal power is 1 mW. (2 marks) h) Find the probability of error Pe of the received PCM signal. (2 marks) i) What shall we do to transmit this PCM signal using Unipolar NRZ over a channel which has a bandwidth of only 5 KHz?Explain. (2 marks) QUESTION 3 a) An audio signal of bandwidth 4 kHz is sampled at a rate of 25% above the Nyquist rate and quantized. The quantization error is not to exceed 0.1% of the signal peak amplitude. The resulting quantized samples are now coded and transmitted by 4-ary pulses. (i) Determine the minimum number of 4-ary pulses needed to encode each sample. (2 marks) (ii) Determine the minimum transmission bandwidth required to transmit this data with zero ISI. (2 marks) (iii) Determine the transmission bandwidth required if raised-cosine 4-ary pulses with 25% roll-off are used. (2 marks) b) An analog signal of bandwidth 10 kHz is sampled at a rate of 24 ksamples/s quantized into 256 samples and coded using M-ary multilevel pulses satisfying the Nyquist criterion with a roll-off factor r=0.2. A 30 kHz bandwidth is available to transmit the data. Determine the smallest acceptable value of M. (6 marks) c) A multilevel digital system sends one of 16 possible levels over a channel every 0.5 ms (i) What is the number of bits corresponding to each level? (2 marks) (ii) What is the bit rate?
Adi S.
The following sub-parts addresses the quantization and rounding principle as well as the effect of under sampling. Answer the following: i. A digital signal processing system, with a twelve-bit uniformly quantizing analogue-to-digital converter and a sampling rate of 16 kHz, is used to process analogue signals band-limited to the frequency range 0 Hz to 4 kHz. Estimate the maximum achievable signal-to-quantization noise ratio (SQNR) for sinusoidal input signals, and state what assumptions it is reasonable to make about the statistical and spectral properties of the quantization noise. ii. Use MATLAB to Quantize a Random White Noise Signal. Quantize a Random White Noise Signal (use randn(1,N) with N the number of samples generated) and compute the mean square error (MSE) and plot the histogram of the quantization error. Comment if this reflects the theory well – i.e. by comparing the histogram with the theoretical PDF model and/or by calculating the theoretical error and comparing against the measured. Hint: Mean Square Error is calculated using: MSE = sum((Sq-S).^2)/N, with Sq the quantized signal samples and S the ‘‘Signal’’ samples generated by the random noise generator. Quantization can be calculated by shifting a continuous number left by ‘‘2^M’’ and then rounding the result to the nearest digit. Divide by 2^M on the rounded number – i.e. Sq = (2^(-M))*(round((2^M)*S)) with M the number of bits. Since you are using MATLAB to assist, please cut and paste any plots or code you used with your answer. iii. Consider a Sinewave with frequency f = 10KHz sampled at fc = 15KHz. Explain if this Sinusoid is sampled according to Nyquist’s theorem regarding minimum sampling rate and calculate the resultant Sinusoid assuming we have a perfect reconstruction filter. Let the original Sinewave be x(t) = cos(10000̀t).
Anand K.
Question 3 a. A communication system transmits an analog waveform via a Yagi antenna of length 3m. The analog waveform is carrier modulated and transmitted over a Maray PAM system, where the number of pulse levels is M = 64. The quantization distortion must not exceed ± 2% of the peak to peak analog signal. i. What is the maximum number of bits per sample that should be used in this PCM? ii. What is the minimum sampling rate? iii. Determine the maximum frequency iv. What's the resulting bit transmission rate? v. Compute the sampling time [10 marks] b. The bandwidth of a video signal is 4.5 MHz This signal is to be transmitted using Pulse Code Modulation with the number of quantization levels Q = 1024. The sampling rate should be a certain percentage higher than the Nyquist rate. How best would you analyze the system bit rate to enable transmission of the video signal? Choose your own percentage ranging between 20% and 50%. [8 marks] c. In digital communication it is said that Analog information sources can be transformed into digital sources through what is described as what. In one page discuss the method and process. [5 marks]
Sri K.
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