📡 Telecommunication Notes

Telecommunication ek aisa system hai jisme information (voice, video, data) ek jagah se dusri jagah tak transmit hoti hai using wires, optical fiber ya wireless channels. Yahan aapko short aur exam-friendly Hinglish notes milenge.

Core Devices in Telecom

  • Modem – Ye digital signals ko analog aur analog ko digital me convert karta hai. Internet connection ke liye sabse zaroori device.
  • Router – Ye data packets ko alag-alag networks ke beech forward karta hai. Matlab ghar ka Wi-Fi bhi router se hi chalta hai.
  • Repeater – Jab signal weak ho jata hai toh repeater usko regenerate karke aage bhejta hai. Mostly Physical layer pe kaam karta hai.
  • Gateway – Different networks jinke protocols alag ho unko connect karne ka kaam karta hai.
  • Bridge – Do LAN ko connect karta hai jo same protocol use karte hain.
Tip: Router ko internet chalane ke liye modem ki zaroorat hoti hai, but modem akela bhi work kar sakta hai.

Modulation & PCM

Modulation ka matlab hai digital signal ko transmission ke liye analog me convert karna. Demodulation me analog signal ko wapas digital me badla jata hai. Aur PCM (Pulse Code Modulation) ek technique hai jisme analog signal ko digital form me represent kiya jata hai (jaise audio CDs, digital telephony).

Multiplexing

Multiplexing ek technique hai jisme ek hi medium par multiple signals bheje jaate hain.

  • TDM (Time Division Multiplexing) – Har signal ko alag-alag time slot milta hai (best for digital signals).
  • FDM/WDM – Different frequencies ya wavelengths use hote hain (mainly analog & optical fiber me).

ISDN & PSDN

  • ISDN (Integrated Services Digital Network) – 1988 me launch hua tha. Ye ek hi line par voice, video aur data transmission allow karta hai.
  • PSDN (Public Switched Data Network) – Ye ek public data service network hai jo wide area me data transfer karta hai.

📝 Quick Quiz

  1. Modem ka kaam kya hota hai?
  2. Kaunsi multiplexing digital signals ke liye use hoti hai?
  3. Repeater kis problem ko solve karta hai?
  4. PSDN ka full form likho.
Answers
  • Digital ↔ Analog conversion
  • TDM (Time Division Multiplexing)
  • Weak signal ko regenerate karta hai
  • Public Switched Data Network

✅ Conclusion

Ye Telecommunication notes aapko Library Science ke exam aur interviews ke liye help karenge. Agar aap aur detail ya diagrams (jaise TDM slots, Modem working) chahte ho toh unhe bhi add kiya ja sakta hai.