Are these Digital Communication handwritten notes free?

Yes. Fill in the short form on this page and the PDF downloads right away. There is no fee for the notes.

Are these official university notes?

No. These are original Uncodemy revision notes for Digital Communication. They are not issued or approved by AKTU or any other university, and they are not past papers.

Which syllabus do they follow?

They follow the common B.Tech syllabus for Digital Communication used by most Indian universities, including AKTU and colleges on the AICTE model curriculum. Unit order and depth differ, so match the notes with your own university syllabus.

Does the PDF cover information theory?

Yes. There is a full unit on information theory, including entropy, source coding with Huffman codes and the Shannon-Hartley channel capacity.

Should I study analog communication first?

It helps, because noise and modulation ideas carry over. Many universities teach Analog Communication in the earlier semester for this reason.

Digital Communication Handwritten Notes PDF

Key takeaways

Eight units, from PCM and quantisation to error control coding and TDM.
SQNR, bit rate and slope overload are explained with formulas and a PCM example.
ASK, FSK, PSK, QPSK and DPSK are compared on bandwidth and error performance.
Entropy, Huffman coding, Shannon capacity, Hamming codes and CRC are included.
Original Uncodemy revision notes, not official university notes. Check your own syllabus.

About these handwritten notes

These Digital Communication notes are original Uncodemy revision notes, written in a clean handwritten style so they are quick to read before an exam. They follow the common B.Tech syllabus for Digital Communication (B.Tech ECE and GATE EC basics). They are not official university notes and not copied from any textbook or past paper.

Topic order, unit numbers and depth vary between universities, so first place each unit below against your own university syllabus. If your syllabus has a topic that is missing here, add it in the margin from your class notes or textbook. Use these notes for revision after you have studied the topic once in class, not as your only study material. They are short on purpose: the aim is to help you recall the main ideas, formulas and diagrams quickly, so that your exam time goes into writing good answers.

What's inside the Digital Communication notes

The PDF follows the path of a digital signal: from sampling and coding, through the channel, to detection and error correction. Each unit has formula boxes and exam tips.

Unit 1: Introduction. Elements of a digital communication system and why digital is preferred over analog.
Unit 2: Sampling and Pulse Code Modulation (PCM). Quantisation, quantisation noise, SQNR, companding, DPCM and delta modulation with slope overload.
Unit 3: Baseband Transmission. Line codes, inter-symbol interference, the Nyquist criterion and raised cosine pulses.
Unit 4: Optimum Detection. Matched filter, its maximum SNR and the correlation receiver.
Unit 5: Digital Modulation (Passband). ASK, FSK, BPSK, QPSK and DPSK, with bandwidth and bit error rate comparison.
Unit 6: Information Theory. Entropy, information rate, Huffman and Shannon-Fano coding, and the Shannon-Hartley channel capacity.
Unit 7: Error Control Coding. Linear block codes, Hamming codes, syndrome decoding, cyclic codes and CRC.
Unit 8: Multiplexing and Synchronisation. TDM hierarchies such as E1, and bit and frame synchronisation.

The last page of the PDF lists the most asked practice questions for the whole subject, so you can test yourself after finishing all the units.

Formulas and solved examples in the PDF

Formula boxes cover SQNR = 1.76 + 6.02n dB, PCM bit rate, raised cosine bandwidth, matched filter SNR, entropy and channel capacity. Solved examples include a PCM numerical, raised cosine bandwidth for 10 kbps with roll-off 0.5, a BPSK error numerical, an entropy and Huffman example, channel capacity for a 3 kHz channel at 30 dB SNR, and the E1 bit rate of 2.048 Mbps.

How to revise Digital Communication with handwritten notes

Handwritten-style notes work best when you read actively. Keep a pen and a rough notebook beside you, cover the formula or diagram, and try to write it yourself before you look.

Keep one formula page for PCM: bit rate, step size, quantisation noise Δ²/12 and SQNR.
Write the BER table for ASK, FSK, BPSK and QPSK once, then test yourself on it without looking.
For Huffman coding, practise building the tree for at least two different sources and check the average length against entropy.
For Hamming codes, practise one full cycle: encode, add a single error, find the syndrome and correct it.

In the last week, read only the formula boxes and exam tips, and solve one numerical or long question per unit from memory. If you study with friends, ask each other to explain one diagram or derivation aloud. Explaining a topic is the fastest way to find the gaps in it.

A short revision plan

If your exam is about a week away, this plan covers every unit in the PDF once and leaves time for practice. Stretch it over two weeks if you are starting from scratch.

Day 1: Introduction, Sampling and Pulse Code Modulation (PCM).
Day 2: Baseband Transmission, Optimum Detection.
Day 3: Digital Modulation (Passband), Information Theory.
Day 4: Error Control Coding, Multiplexing and Synchronisation.
Day 5: Solve the practice questions in the exam focus section below, one per unit, without the notes.
Day 6: Read only the formula boxes and exam tips, redo the numericals you got wrong, and sleep early.

Common mistakes to avoid

Using the number of levels L instead of the number of bits n in the SQNR formula. n = log2 L.
Forgetting the factor (1 + α) when finding raised cosine bandwidth.
Mixing bits per symbol and symbols per second when comparing BPSK and QPSK bandwidth.
Taking the SNR in dB directly in the Shannon formula. Convert it to a ratio first.

How Digital Communication links to other subjects

Digital Communication builds on Signals and Systems (sampling and the Fourier transform), probability, and Analog Communication (noise and modulation). It leads into Wireless and Mobile Communication, Computer Networks and information and coding theory electives.

Exam focus: high-weightage topics

University papers usually give the most weight to PCM and SQNR, delta modulation, ISI and the Nyquist criterion, the matched filter, digital modulation schemes, information theory and Hamming codes. Entropy, capacity and PCM bit rate are frequent numericals.

Typical long and numerical questions to practise:

Explain PCM with a block diagram, then find its bit rate and SQNR.
What is slope overload in delta modulation? Derive the condition to avoid it.
Explain ISI and the Nyquist criterion. What is a raised cosine pulse?
Derive the matched filter and its maximum SNR.
Find entropy and construct a Huffman code for a given source.
Find code words, syndrome and the corrected word for a (7, 4) Hamming code.

When you write a long answer, start with a one-line definition, draw the diagram or circuit, write the derivation in clear steps and end with the final result and its unit. For numericals, write the formula first, then substitute, so you can still earn step marks if the arithmetic slips.

These are practice questions based on common syllabus topics. They are not verified past papers, and we do not claim any question will appear in your exam. For real previous papers, use your university's official archive.

Who these notes are for

These notes are for B.Tech ECE students preparing for their Digital Communication semester exam, and for students revising GATE EC basics such as entropy, capacity, PCM bit rate and BER. They are also useful before telecom, networking or embedded interviews, where questions on modulation, coding and CRC come up.

Download Digital Communication Handwritten Notes PDF