Communication System Assignment PDF

Faculty of Electrical and Computer Engineering Jimma Institute of Technology, JiT Introduction to Communication System (ECEg4164) Assignment and Worksheet 01/11/2025 1. Clea...

Faculty of Electrical and Computer Engineering Jimma Institute of Technology, JiT Introduction to Communication System (ECEg4164) Assignment and Worksheet 01/11/2025 1. Clearly state how PPM is derived from PWM? 2. What are the advantages and disadvantages of digital transmission? 3. Compare WBFM and NBFM. 4. A single-tone FM is represented by the voltage equation: 𝑣(𝑡) = 12 cos(6 × 108 𝑡 + 5 sin(1250𝑡)). Determine the following: A. Carrier frequency B. Modulation index C. Modulating frequency D. Maximum deviation v E. What power this FM wave will dissipate in 10 Ohm resistor 5. An angle modulated signal is given by Φ𝑁𝐵𝐹𝑀 (t) = 4 cos(2𝜋 × 106 𝑡 + 2 sin(2𝜋 × 103 𝑡) + 4 sin(4𝜋 × 103 𝑡)) A. What is the bandwidth of the angle modulated signal? (Carson's rule) B. If the angle modulated signal is an FM signal with a frequency deviation constant of 4𝜋 × 103 𝑟𝑎𝑑/𝑠𝑒𝑐/𝑣𝑜𝑙𝑡, determine the message signal 𝑚(𝑡). C. What is the value of the frequency deviation ratio (i.e. modulation index)? 6. A 100 MHz un-modulated carrier delivers 100 Watts of power to a load. The carrier is frequency modulated by a 2 kHz modulating signal causing a maximum frequency deviation  of 8 kHz. This FM signal is coupled to a load through an ideal Band Pass filter with 100MHz as center frequency and a variable bandwidth. A. Calculate modulation index B. Determine the number of sets of significant side frequencies C. Calculate their powers of each significant side frequencies D. Determine the total power that can be delivered to the load when the filter bandwidth is10.5 kHz and 21 kHz. 7. The bandwidth of an input signal to the PCM is restricted to 4 kHz. The input signal varies in amplitude from -3.8 V to +3.8 V and has the average power of 30 mW. The required signal to noise ratio is given as 20 dB. The PCM modulator produces binary output. Assuming uniform quantization, A. Find the number of bits required per sample. B. Outputs of 30 such PCM coders are time multiplexed. What would be the minimum required transmission bandwidth for this multiplexed signal? 8. Suppose that the modulating signal 𝑚(𝑡) = 10 sin(2𝜋 × 103 𝑡) is used to modulate a carrier signal 𝑐(𝑡) = 10 sin(2𝜋 × 104 𝑡). Using MATLAB plot the time and frequency domain representation of modulating signal, carrier signal, as well as modulated and demodulated signals of: A. AM B. DSB-SC C. SSB D. Apply filtering techniques for demodulating the mentioned modulation methods and compare the results with the demodulated signals without filtering. 9. A signal 𝑚(𝑡) frequency modulates 100 𝑘𝐻𝑧 carrier to produce the following narrowband FM signal: Φ𝑁𝐵𝐹𝑀 (t) = 5 cos(2𝜋 × 105 𝑡 + 0.005 sin(2𝜋 × 104 𝑡)) Design the wideband FM signal) Φ𝑊𝐵𝐹𝑀 (t) with a carrier frequency of 75𝑀𝐻𝑧 and a frequency deviation of 75 𝑘𝐻𝑧. Use block diagram to show the design. Assume that the following are available for the design:  Frequency Multipliers of any integer value   A local oscillator whose frequency can be tuned to any value between 50 𝑀𝐻𝑧 to 150 𝑀𝐻𝑧  An ideal band pass filter with tunable center frequency and bandwidth Your block diagram design must clearly specify the carrier frequencies and frequency deviations at all logical points, as well as the center frequency and bandwidth of the band pass filter. 10. Sketch the digitally modulated waveforms for the binary data 𝑉𝑑 (𝑡) and carrier signals 𝑉𝐶1 (𝑡), 𝑉𝐶2 (𝑡) using ASK, FSK. 11.Determine the minimum transmission BW in a TDM system transmitting 20 different messages, each message signal have BW of 5 kHz; compare the result if FDM is used with AM & SSB techniques. 12. Design a MATLAB-based communication system by applying M-ary PSK and QAM modulation-demodulation techniques, and evaluating the BER performances. Which modulation types and M-ary orders (low or high order M-ary) are best for satellite and 5G, and why? Submission Date: 01/17/2025 Submit: Question 4 to 12 Mark: 20 (given based on clarity) For MATLAB: Submit with code & Discuses what the figure shows