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This document contains 10 questions related to digital communication systems for an assignment. The questions cover topics such as sampling, PCM, DM systems, orthogonalization, QAM, matched filters, error probability calculations for various modulation schemes, pseudo-noise sequences, equalization techniques, and an overview of the roadmap to 6G wireless networks. Students are asked to sketch spectra, calculate signaling rates, determine minimum quantization levels/bits, compute impulse responses, derive error probabilities, construct PN sequences, explain equalizer types, and elaborate on the path to 6G.

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87 views3 pages

Assignament 1

This document contains 10 questions related to digital communication systems for an assignment. The questions cover topics such as sampling, PCM, DM systems, orthogonalization, QAM, matched filters, error probability calculations for various modulation schemes, pseudo-noise sequences, equalization techniques, and an overview of the roadmap to 6G wireless networks. Students are asked to sketch spectra, calculate signaling rates, determine minimum quantization levels/bits, compute impulse responses, derive error probabilities, construct PN sequences, explain equalizer types, and elaborate on the path to 6G.

Uploaded by

NAGARAJU S M
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Fall 2022-23

ECE 4001 DCS – Digital Assignment

School of Electronics Engineering


Digital Assignment
Fall 2022-23
Course code and Name: ECE 4001 Digital Communication Systems

Slot: G1+TG1

1) A sinusoidal signal 𝑥(𝑡) = cos(2𝜋 × 103 𝑡) + cos⁡(𝜋 × 103 𝑡) is sampled at a rate of


1500 samples per second. The sampled signal is passed through an ideal low pass filter
(LPF) with cut off frequency at 750 Hz. Sketch the spectrum and determine the LPF
output frequency/frequencies.

2) a)Consider binary PCM transmission of a video signal with 𝑓𝑠 = 10⁡𝑀𝐻𝑧. Calculate


the signalling rate needed to achieve (𝑆𝑅𝑁)𝑜 ≥ 45⁡𝑑𝐵.
b)Consider an audio signal with spectral components limited to the frequency band of
300 Hz to 3300 Hz. A PCM signal is generated with a sampling rate of 8000 samples/s.
The required output signal-to-quantization-noise ratio is 30 dB.
(i) What is the minimum number of uniform quantization levels needed and what is the
minimum number of bits per sample is needed?
(ii) Calculate the minimum system bandwidth is required.

3) In a single-integration DM system, the voice signal is sampled at a rate of 64 kHz,


similar to PCM. The maximum signal amplitude is normalized to 1 V.
a) Determine the minimum value of step size to avoid slope overload distortion.
b) Assume the voice signal is sinusoidal then compute SNR.
c) Determine the transmission bandwidth.

4) Three signals 𝑆1 (𝑡),𝑆2 (𝑡)𝑎𝑛𝑑⁡𝑆3 (𝑡) are shown in Figure 1.

(i) Using the Gram-Schmidt orthogonalization procedure find the orthonormal


basis function.
(ii) Find the signal co-ordinates.

Page 1 of 3
Fall 2022-23
ECE 4001 DCS – Digital Assignment

Figure 1
5) Explain the principle of Quadrature Amplitude Modulation (QAM)

6) The message signal m1(t) is shown in Figure 2.


(i) Compute the impulse response of the matched filter.
(ii) Derive the output of the matched filter.

Figure 2

Page 2 of 3
Fall 2022-23
ECE 4001 DCS – Digital Assignment
7) A microwave link transmits data at a rate of 200 kbps. Assuming the channel is AWGN
with zero mean and power spectral density is 2 × 10−10 ⁡W/Hz. The average carrier
power os the system is 2.24 × 10−4 𝑊 . Determine its average probability of error for
the following system.
(i) Coherent FSK
(ii) Coherent QPSK
(iii) Coherent MSK
(iv) DPSK
(v) Non-Coherent FSK.

8) Construct the Pseudo Noise (PN) sequence using the feedback shift register
[5, 4, 3, 2]

9) What is equalization technique? Explain its different types.

10) Elaborate the road map to 6G.

Page 3 of 3

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