AKTU Communication Engineering · Important Questions 2026Source: ryzenstudy.com PYQs
BEC401 Communication Engineering Important Questions 2026 (AKTU)
Repeat analysis + most-asked questions, unit-wise
What we did: built from all 5 AKTU Communication Engineering papers (2021-22–2025-26): 116 questions grouped into 68 distinct questions, 26 of which were asked in more than one paper.
- of marks were repeat questions
- 51%
- of marks were repeat questions
- questions asked in 2+ papers
- 26
- questions asked in 2+ papers
- papers analysed (2021-22–2025-26)
- 5
- papers analysed (2021-22–2025-26)
- units, mapped to current syllabus
- 5
- units, mapped to current syllabus
How much of the paper repeats?
- Repeats are real: when we checked each newer BEC401 paper against the papers before it, on average 51% of its marks were questions already asked in an earlier paper.
- 2023-24 paper: 42% of marks were repeats (6 of 9 repeated questions were in our top list).
- 2024-25 paper: 56% of marks were repeats (10 of 12 repeated questions were in our top list).
- 2025-26 paper: 56% of marks were repeats (6 of 13 repeated questions were in our top list).
- Topic weightage is a guide, not a guarantee: our Tier 1 + Tier 2 topics covered 73% of the next paper's marks — picking the same number of topics at random would have covered about 55%.
Across 10 subjects and 23 papers we tested, 43% of marks repeated earlier questions on average.
1.Unit-wise most-asked questions
Ranked by how many papers asked them, then by how recently. Click a paper to open it.
Unit 1:
22% of past marks| Question | Asked |
|---|---|
| State the need of modulation in communication system. | Asked 4× |
| Explain working of DSB-SC Modulator and Demodulator. | Asked 3× |
| The antenna current of an AM broadcast transmitter, modulated to a depth of 30% by an audio sine wave is 10 A. It increases to 12 A as a result of sinusoidal modulation by another audio sine wave. What is the modulation index due to second wave? | Asked 2× |
| Calculate the transmission efficiency of an AM signal with 100% modulation. | Asked 2× |
Unit 2:
19% of past marks| Question | Asked |
|---|---|
| Demonstrate the generation of FM with the help of PM and vice-versa. | Asked 3× |
| State Carson's rule for the bandwidth of an FM signal. | Asked 3× |
| Explain the demodulation of an FM wave using a phase locked loop with a functional block diagram. | Asked 2× |
| Illustrate Narrow Band Frequency Modulation with mathematical expression. | Asked 2× |
Unit 3:
19% of past marks| Question | Asked |
|---|---|
| Explain the concepts of pre-emphasis and de-emphasis in FM and derive how they improve SNR. | Asked 5× |
| Derive the expression for the signal to noise ratio and figure of merit for a double side band suppressed carrier system. | Asked 3× |
| What is Figure of Merit? | Asked 3× |
| State the various types of noises encountered in a communication system. | Asked 2× |
Unit 4:
23% of past marks| Question | Asked |
|---|---|
| Draw and explain block diagram of PCM. Also explain SNR in PCM. | Asked 4× |
| Explain the sampling theorem and its significance in the context of pulse modulation. What happens if the sampling rate is below the Nyquist rate? | Asked 3× |
| Find the Nyquist rate and Nyquist interval for the signal x(t) = 20sin(100πt) cos(200πt). | Asked 3× |
| Discuss the process of quantization in PCM. Prove that for a PCM signal, the signal to quantization noise ratio in dB is 1.8 + 6n approximately, where n is the number of bits per sample. | Asked 2× |
Unit 5:
18% of past marks| Question | Asked |
|---|---|
| Briefly explain the concept of quadrature amplitude modulation. | Asked 4× |
| Explain Minimum Shift Keying (MSK) in detail. | Asked 3× |
| Explain QPSK in short. | Asked 3× |
| Draw and explain the block diagram for a binary frequency shift keying transmitter and receiver. | Asked 2× |
2.Topic weightage: which topics carry the marks
Blue = Tier 1 + Tier 2 (topics that carried ~80% of past marks). Grey = the rest. It shows where marks have gone, not a promise of what comes next.
Principles of AM (DSB-FC) · U1
12% (cum 12%)
FM signal representation · U2
9.2% (cum 21%)
Spectral characteristics of angle modulation · U2
7% (cum 28%)
Noise in AM systems · U3
7% (cum 35%)
Phase shift keying · U5
6.6% (cum 42%)
Pulse code modulation · U4
6.5% (cum 48%)
Delta modulation · U4
6.2% (cum 55%)
Pre-emphasis and de-emphasis · U3
5.5% (cum 60%)
Sampling process · U4
5% (cum 65%)
Quadrature amplitude modulation · U5
4.3% (cum 69%)
DSB-SC modulation · U1
4.1% (cum 73%)
Continuous phase modulation and MSK · U5
4.1% (cum 77%)
Probability and random process · U3
3.3% (cum 81%)
Frequency domain representation · U1
3.2% (cum 84%)
Gaussian and white noise · U3
3.1% (cum 87%)
Frequency shift keying · U5
2.8% (cum 90%)
SSB modulation · U1
2.3% (cum 92%)
Time division multiplexing · U4
2.2% (cum 94%)
Noise in PCM · U4
2.1% (cum 96%)
PM signal representation · U2
1.5% (cum 98%)
Angle modulation basics · U2
1.1% (cum 99%)
Pulse amplitude modulation · U4
0.6% (cum 100%)
Differential PCM · U4
0.4% (cum 100%)
| Topic | Papers | Share |
|---|---|---|
| Principles of AM (DSB-FC) · Unit 1 · Tier 1 | 5/5 | 12% |
| FM signal representation · Unit 2 · Tier 1 | 5/5 | 9.2% |
| Spectral characteristics of angle modulation · Unit 2 · Tier 1 | 5/5 | 7% |
| Noise in AM systems · Unit 3 · Tier 1 | 5/5 | 7% |
| Phase shift keying · Unit 5 · Tier 1 | 4/5 | 6.6% |
| Pulse code modulation · Unit 4 · Tier 1 | 5/5 | 6.5% |
| Delta modulation · Unit 4 · Tier 1 | 4/5 | 6.2% |
| Pre-emphasis and de-emphasis · Unit 3 · Tier 2 | 5/5 | 5.5% |
| Sampling process · Unit 4 · Tier 2 | 4/5 | 5% |
| Quadrature amplitude modulation · Unit 5 · Tier 2 | 4/5 | 4.3% |
| DSB-SC modulation · Unit 1 · Tier 2 | 4/5 | 4.1% |
| Continuous phase modulation and MSK · Unit 5 · Tier 2 | 4/5 | 4.1% |
| Probability and random process · Unit 3 · Tier 2 | 3/5 | 3.3% |
| Frequency domain representation · Unit 1 · Tier 3 | 3/5 | 3.2% |
| Gaussian and white noise · Unit 3 · Tier 3 | 3/5 | 3.1% |
| Frequency shift keying · Unit 5 · Tier 3 | 3/5 | 2.8% |
| SSB modulation · Unit 1 · Tier 3 | 2/5 | 2.3% |
| Time division multiplexing · Unit 4 · Tier 3 | 3/5 | 2.2% |
| Noise in PCM · Unit 4 · Tier 3 | 2/5 | 2.1% |
| PM signal representation · Unit 2 · Tier 3 | 1/5 | 1.5% |
| Angle modulation basics · Unit 2 · Tier 3 | 1/5 | 1.1% |
| Pulse amplitude modulation · Unit 4 · Tier 3 | 1/5 | 0.6% |
| Differential PCM · Unit 4 · Tier 3 | 1/5 | 0.4% |
3.Paper pattern (2025-26)
| Section | Questions | Rule |
|---|---|---|
| A | 7 × 2 marks | Attempt all |
| B | 5 × 7 marks | Attempt any 3 |
| C | 10 × 7 marks | Attempt any 1 |
4.In the syllabus, never asked yet
Low priority, but read them once — a new paper can always start here.
- Signals and systems review · U1
- VSB modulation · U1
- Noise in FM systems · U3
- Threshold effect · U3
5.Study order
- 1Principles of AM (DSB-FC) (Unit 1, Tier 1)
- 2FM signal representation (Unit 2, Tier 1)
- 3Spectral characteristics of angle modulation (Unit 2, Tier 1)
- 4Noise in AM systems (Unit 3, Tier 1)
- 5Phase shift keying (Unit 5, Tier 1)
- 6Pulse code modulation (Unit 4, Tier 1)
- 7Delta modulation (Unit 4, Tier 1)
- 8Pre-emphasis and de-emphasis (Unit 3, Tier 2)
- 9Sampling process (Unit 4, Tier 2)
- 10Quadrature amplitude modulation (Unit 5, Tier 2)
- 11DSB-SC modulation (Unit 1, Tier 2)
- 12Continuous phase modulation and MSK (Unit 5, Tier 2)
- 13Probability and random process (Unit 3, Tier 2)
FAQ
Which units of BEC401 carry the most marks?
Unit 4 (, 23% of past marks) and Unit 1 (, 22% of past marks).
Do AKTU Communication Engineering questions repeat?
Yes. On average 51% of the marks in each newer BEC401 paper came from questions already asked in an earlier paper, and 26 questions have appeared in more than one paper.
How is this list made?
Every question from the 5 papers (2021-22–2025-26) was mapped to the current AKTU syllabus and grouped with the same question from other years. Questions are ranked by how many papers they appeared in, then by how recently.
Study this subject
Note: this is based on past AKTU papers, not a guarantee. Questions are mapped to the current syllabus; topics that are no longer in the syllabus are left out.