Encoding Techniques in Computer Networks 

 Encoding Kya Hota Hai?

Encoding ek process hai jisme digital data (0s aur 1s) ko aise signal mein convert kiya jata hai jo kisi wire, fiber, ya wireless medium se bheja ja sake.

Data (0/1) → Signal → Transmission

Sochiye aapke paas ek message hai jo aapko kisi wire ke through bhejna hai. Computer ye message ko 0s aur 1s mein convert karega, aur encoding technique us 0/1 ko signal mein badalti hai jo wire ke through travel kar sake.

 Types of Encoding Techniques

Encoding ke mainly 3 types hote hain:

1. Line Encoding

2. Block Encoding

3. Multilevel Encoding

Sabse common aur easy-to-understand hai Line Encoding, toh shuru ussi se karte hain.

 1. Line Encoding

Isme har bit (0 ya 1) ko ek specific signal se represent kiya jata hai.

 A) Unipolar NRZ (Non-Return-to-Zero)

• 1 = High voltage

• 0 = Zero voltage (no signal)

• Signal kabhi “zero” pe wapas nahi aata, isliye Non-Return-to-Zero

 Example:

 Pros: Bahut simple hota hai
 Cons: Agar bohot saare 0 ya 1 aa gaye to signal change nahi hota, sync muskil ho jata hai

 B) Polar NRZ

• 1 = Positive voltage

• 0 = Negative voltage

• 0 aur 1 ke liye alag-alag voltage use hoti hai

 Example:

 Pros: Better than unipolar
 Cons: Long same bits ke sequence se sync kharab ho sakta hai

 C) Manchester Encoding

• Har bit ke middle mein transition hoti hai

  • 0 = High to Low

  • 1 = Low to High

 Pros: Har bit mein change hota hai → synchronization perfect
 Cons: Har bit ke liye double bandwidth lagti hai

 D) Differential Manchester

• Har bit ke beech mein transition fix hoti hai

• 0 = Start of bit mein transition

• 1 = Start of bit mein no transition

 Pros: Reliable in noisy environments
 Cons: Samajhna aur implement karna thoda mushkil

 E) Bipolar AMI (Alternate Mark Inversion)

• 0 = No voltage

• 1 = Alternating + and – voltage

  • 1st 1 = +

  • 2nd 1 = –

  • 3rd 1 = + … and so on

 Example:

 Pros: Voltage average zero hota hai → long distance transfer possible
 Cons: Agar zyada 0s aa jayein to signal weak ho jata hai

 2. Block Encoding (e.g., 4B/5B)

• Yahan bits ko groups mein divide karte hain.

• Har 4-bit block ko 5-bit code mein convert karte hain

• Iss se long 0s ka issue solve hota hai, aur sync better hota hai

 Example:

 Pros: Sync aur error detection mein help karta hai
 Cons: Thoda extra data send karna padta hai (overhead)

 3. Multilevel Encoding (e.g., 2B1Q)

• Isme ek signal level 2 bits ko represent karta hai

• Total 4 levels hoti hain (quaternary = 4 levels)

 Example Mapping:

 Pros: Kam bandwidth mein zyada data transfer hota hai
 Cons: Encoding aur decoding complex hoti hai

 Comparison Table

 Real-Life Analogy

Sochiye aap aur aapka friend code language mein baat kar rahe ho.

• Agar aap clap karte ho to iska matlab 1, aur silence rakhte ho to 0.

• Lekin agar aap baar-baar clap kare bina rukte ho to samne wala confused ho sakta hai.

• Isliye aap decide karte ho:

  • Har bit ke beech mein pause (Manchester style)

  • Ya clap ki direction change karte ho (Bipolar style)

Yahi kaam computer networks mein encoding karti hai!

 Final Summary