AKTU Signal System · Important Questions 2026Source: ryzenstudy.com PYQs
BEC403 Signal System Important Questions 2026 (AKTU)
Repeat analysis + most-asked questions, unit-wise
What we did: built from all 5 AKTU Signal System papers (2021-22–2025-26): 119 questions grouped into 58 distinct questions, 28 of which were asked in more than one paper.
- of marks were repeat questions
- 70%
- of marks were repeat questions
- questions asked in 2+ papers
- 28
- 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 BEC403 paper against the papers before it, on average 70% of its marks were questions already asked in an earlier paper.
- 2023-24 paper: 53% of marks were repeats (8 of 12 repeated questions were in our top list).
- 2024-25 paper: 72% of marks were repeats (11 of 17 repeated questions were in our top list).
- 2025-26 paper: 83% of marks were repeats (12 of 18 repeated questions were in our top list).
- Topic weightage is a guide, not a guarantee: our Tier 1 + Tier 2 topics covered 74% of the next paper's marks — picking the same number of topics at random would have covered about 53%.
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:
21% of past marks| Question | Asked |
|---|---|
| Check the system y(t) = x²(t) + 2 for linearity, causality, and time-invariance (see original paper for the exact equation). | Asked 5× |
| Determine if the given signal x(t) = e^(-2t) u(t) is an energy or power signal (see original paper for the exact exponent). | Asked 4× |
| Define even and odd signals. Determine the even and odd components of the given signal (see original paper). | Asked 4× |
| Determine the fundamental period of the signal x(t) = cos(10t) + sin(20t), if it is periodic. | Asked 3× |
Unit 2:
19% of past marks| Question | Asked |
|---|---|
| Compute the convolution integral of x(t) = u(t) and h(t) (see original paper). | Asked 3× |
| What is convolution? Write its significance in LTI systems. | Asked 3× |
| An LTI system is described by the differential equation (see original paper). Find the impulse response of the system. | Asked 2× |
| Check whether the system is BIBO stable and causal or not. | Asked 2× |
Unit 3:
25% of past marks| Question | Asked |
|---|---|
| Using the Fourier transform, find the convolution of x1(t) = e^(-at) u(t) and x2(t) = e^(-bt) u(t). | Asked 4× |
| Find the inverse Laplace transform of the given X(s) for the ROC (see original paper). | Asked 4× |
| Sketch the signal y(t) = e^(-a|t|) and find the Fourier transform of the same signal with magnitude and phase curve. | Asked 3× |
| State and prove Parseval's theorem for the continuous-time Fourier transform. | Asked 2× |
Unit 4:
19% of past marks| Question | Asked |
|---|---|
| Use the partial fraction method to find the inverse Z-transform of H(z) (see original paper). | Asked 5× |
| Find the Z-transform and the ROC of the sequence x(n) = (1/3)^n u(n) + (1/2)^n u(-n-1). | Asked 4× |
| Determine the Z-transform and sketch the ROC for x(n) = a^n sin(ω0 n) u(n). | Asked 3× |
| Define the region of convergence (ROC) and its significance in Z-transforms. | Asked 2× |
Unit 5:
16% of past marks| Question | Asked |
|---|---|
| State and prove the sampling theorem for low-pass signals. | Asked 4× |
| A signal x(t) = sinc(100t) + 3 sinc(60t) is to be sampled. (i) Identify the maximum frequency component, (ii) Calculate the Nyquist sampling rate and Nyquist sampling interval (see original paper to confirm the signal). | Asked 3× |
| Explain the reconstruction of a signal from its samples using an ideal interpolation filter. | Asked 3× |
| Briefly explain the concept of aliasing in sampling. | 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.
Fourier transform and properties · U3
13.1% (cum 13%)
Signal classification · U1
11.8% (cum 25%)
Z-transform and ROC · U4
10.9% (cum 36%)
Convolution · U2
7.3% (cum 43%)
System properties · U1
6.3% (cum 49%)
Impulse and step response · U2
5.9% (cum 55%)
Aliasing and Nyquist rate · U5
5.8% (cum 61%)
Inverse Z-transform · U4
4.8% (cum 66%)
Sampling theorem · U5
4.7% (cum 71%)
Parseval and DTFT · U3
4.3% (cum 75%)
Inverse Laplace and system analysis · U3
3.8% (cum 79%)
Signal reconstruction · U5
3% (cum 82%)
Types of sampling · U5
2.8% (cum 84%)
Stability and causality of LSI systems · U2
2.5% (cum 87%)
Z-domain system analysis · U4
2.2% (cum 89%)
Basic signals and sketching · U1
2.1% (cum 91%)
Differential and difference equations · U2
2% (cum 93%)
Laplace transform and ROC · U3
1.8% (cum 95%)
Frequency response and eigenfunctions · U2
1.7% (cum 97%)
Fourier series · U3
1.6% (cum 98%)
Z-transform properties · U4
1% (cum 99%)
Signal definitions and sampling basics · U1
0.5% (cum 100%)
| Topic | Papers | Share |
|---|---|---|
| Fourier transform and properties · Unit 3 · Tier 1 | 5/5 | 13.1% |
| Signal classification · Unit 1 · Tier 1 | 5/5 | 11.8% |
| Z-transform and ROC · Unit 4 · Tier 1 | 5/5 | 10.9% |
| Convolution · Unit 2 · Tier 1 | 5/5 | 7.3% |
| System properties · Unit 1 · Tier 1 | 5/5 | 6.3% |
| Impulse and step response · Unit 2 · Tier 1 | 3/5 | 5.9% |
| Aliasing and Nyquist rate · Unit 5 · Tier 2 | 4/5 | 5.8% |
| Inverse Z-transform · Unit 4 · Tier 2 | 5/5 | 4.8% |
| Sampling theorem · Unit 5 · Tier 2 | 4/5 | 4.7% |
| Parseval and DTFT · Unit 3 · Tier 2 | 4/5 | 4.3% |
| Inverse Laplace and system analysis · Unit 3 · Tier 2 | 4/5 | 3.8% |
| Signal reconstruction · Unit 5 · Tier 2 | 3/5 | 3% |
| Types of sampling · Unit 5 · Tier 3 | 1/5 | 2.8% |
| Stability and causality of LSI systems · Unit 2 · Tier 3 | 3/5 | 2.5% |
| Z-domain system analysis · Unit 4 · Tier 3 | 2/5 | 2.2% |
| Basic signals and sketching · Unit 1 · Tier 3 | 3/5 | 2.1% |
| Differential and difference equations · Unit 2 · Tier 3 | 2/5 | 2% |
| Laplace transform and ROC · Unit 3 · Tier 3 | 2/5 | 1.8% |
| Frequency response and eigenfunctions · Unit 2 · Tier 3 | 2/5 | 1.7% |
| Fourier series · Unit 3 · Tier 3 | 2/5 | 1.6% |
| Z-transform properties · Unit 4 · Tier 3 | 1/5 | 1% |
| Signal definitions and sampling basics · Unit 1 · Tier 3 | 1/5 | 0.5% |
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.Study order
- 1Fourier transform and properties (Unit 3, Tier 1)
- 2Signal classification (Unit 1, Tier 1)
- 3Z-transform and ROC (Unit 4, Tier 1)
- 4Convolution (Unit 2, Tier 1)
- 5System properties (Unit 1, Tier 1)
- 6Impulse and step response (Unit 2, Tier 1)
- 7Aliasing and Nyquist rate (Unit 5, Tier 2)
- 8Inverse Z-transform (Unit 4, Tier 2)
- 9Sampling theorem (Unit 5, Tier 2)
- 10Parseval and DTFT (Unit 3, Tier 2)
- 11Inverse Laplace and system analysis (Unit 3, Tier 2)
- 12Signal reconstruction (Unit 5, Tier 2)
FAQ
Which units of BEC403 carry the most marks?
Unit 3 (, 25% of past marks) and Unit 1 (, 21% of past marks).
Do AKTU Signal System questions repeat?
Yes. On average 70% of the marks in each newer BEC403 paper came from questions already asked in an earlier paper, and 28 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.