Assignment Spring 2018
Module: Digital Communication (ELEC 20004) ID NUMBER
Level: 2 Max. Marks: 100
Differentiate the types of pulse modulation techniques implemented in communication systems;
Critically evaluate the baseband demodulation and detection techniques;
Critically evaluate digital modulation techniques including multi-level digital modulation.
Please add front title page with your answers uploaded on Moodle.
Each question carries 20 marks.
Assignment weightage is 30 marks. So whatever marks you are scoring out of 100 will scale down to out of 30.
Assignment answers must be computer typed. Please do not write question statement. Just mention the question number.
Font - Times New Roman
Font – Style - Regular
Font - Size - 12
Soft copy of the assignment is to be submitted online in Moodle through turnitin.
Each student has to do the assignment individually.
Explain with suitable diagrams wherever required.
The final assignment must have a Title Page, table of contents, references/ bibliography and page number.
Heading should be with Font Size 14, Bold, and Underline.
You can refer books in Library or use internet resource. But you should not cut and paste material from internet nor provide photocopied material from books. The assignment answers should be in your own words after understanding the matter from the above resources.
Attention to the moderator:
Each student will get 5 questions from Question bank covering all the learning outcomes.
Different set of students will get different parameter values.And some of the questions answer will be according to their id no: as it is taken as input data.
Rules & Regulations
If any coursework assessment is found to be copied from other candidates using unacceptable means, then it shall be cancelled and the total marks awarded will be zero. No chance of resubmission or appeal will be given*.
Your source of information should be mentioned in the reference page clearly. (For example: If it’s from book, you have to mention the full details of the book with title, author name, edition and publisher’s name. If it is from the internet you have to mention the correct URL). Otherwise the assignment will be considered as plagiarized*.
The students may be asked to appear for a viva voce to validate the assignment solutions submitted. The viva voce does not carry any marks.
Title Page must have Assignment Name, Module name, your name, ID, Section and the name of the faculty.
For late submission, 5% of the awarded marks will be deducted for each working day.
For plagiarism, please refer to student guide and clarification uploaded on Moodle.
Refer MIG for feedback dates on assignment.
No assignment will be accepted after one week from the date of submission*.
Date of submission 23/05/2018
* Refer to the MIG for MEC policy on academic integrity and late submission.
2.a A signal is sampled with a sampling frequency of 20 MHz. A design engineer claim that the sampled signal is perfectly reconstructed by low pass filter in each of the following cases: Whether his claim is correct? Give justifications.
The band limiting low pass filter frequency response is zero for all frequencies above 7MHz.
The band limiting low pass filter frequency response is zero for all frequencies above 20MHz.
The band limiting low pass filter frequency response is zero for all frequencies above 10MHz.
(Each carry 3 marks)
2. b. A design engineer claim that the PCM system designed by him for a voice signal band limited to 3300 Hz provides peak signal power to average quantization noise power at the output 90 dB and has following specifications: Number of bits per sample = 16 bits, sampling rate 8000 samples/Sec., bit period = 6 micro sec, minimum channel bandwidth required is 167KHz, a peak signal power of 100 Watt and an average quantization noise power of 1 Watt.
Analyze the system and give justification whether all the specifications given by him are true.
6 An audio recording system uses PCM for storing in a device. If the signal is band limited to 15KHz. Calculate:
The Nyquist rate, (3 Marks)
If the number of quantization levels is 65536, determine the number of binary digits required to encode one sample, (3 Marks)
How many binary digits per second are required to encode the audio signal, (2 Marks)
If the sampling rate is 44100Hz and number of quantization levels = 65536, Calculate
the minimum bandwidth required to transmit the encoded signal (3 Marks)
Derive the equation of SNR in dB and find the SNR of the above system in dB (6 Marks)
What is the minimum storage size required to store the PCM signals for 1 day.
8.a The data rate of binary ASK system is 4.8Mbps. Assuming AWGN channel having a bandwidth of 10MHz, the noise present in the channel has zero mean with power spectral density of 10-15W/Hz. If the received signal amplitude is 1mV, determine the average probability of error for the coherent ASK detector. (10 Marks)
8.b The transmission rate of a FSK binary system is 106 bits per second over a microwave link. Channel noise is AWGN having a zero mean and power spectral density at the receiver side is 10-6 W/Hz. Find
the average carrier power required (7 Marks)
Minimum channel bandwidth required if the average probability error is 10-4
9 A signal g(t) = 10 cos 20?t . cos 200?t is sampled by a pulse train of frequency 250Hz.
Calculate the Nyquist rate for the signal g(t). (5 Marks)
Sketch the spectrum of the resulting sampled signal. (10 Marks)
Specify the minimum cutoff frequency of the ideal reconstruction filter so as to recover g(t) from its sampled signal. (5 Marks)
15. Show that output of the BPSK receiver, v_o (kT_b ) at the end of a bit interval extending from time (k-1) T_b to kT_b is v_o (kT_b )=b(kT_b ).v(P_s/2) T_b
(Use expanded mathematical analysis and derivations to prove the output expression)