--- title: "Optical fiber vs satellite transmission" subject: "Data Communication" chapter: 4 key: "semester_5/data_communication:optical-fiber-vs-satellite" source: https://www.bctengineer.com/q/semester_5/data_communication/optical-fiber-vs-satellite site: BCT Engineering --- # Optical fiber vs satellite transmission Data Communication · Chapter 4: Transmission Media - Asked in: 2071 Chaitra, 6 marks - Answer checked by Claude Sonnet 5.5 on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_5/data_communication/optical-fiber-vs-satellite - Whole chapter: https://www.bctengineer.com/md/semester_5/data_communication/chapter-4 ## Question Compare the transmission characteristics and performance (frequency range, bandwidth, security, flexibility, interference, connectivity) of Optical fiber cable and Satellite transmission. ## Short answer Optical fibre operates at 180-370 THz with Tbps bandwidth, near-zero EMI, very low delay (5 µs/km), and high security, but fixed point-to-point. Satellite microwaves (1-40 GHz) offer wide broadcast coverage and mobility, but suffer from 0.5 s round-trip delay, rain fade, lower security, and limited bandwidth per transponder. ## Answer | Characteristic | Optical fibre cable | Satellite transmission | |---|---|---| | Medium | Guided: light through glass | Unguided: microwaves through space | | Frequency range | 180-370 THz (infrared and visible light) | 1-40 GHz (C, Ku, Ka bands) | | Bandwidth | Extremely high (Tbps with WDM) | Moderate, limited by spectrum and transponders (up to hundreds of Mbps) | | Delay | Low (about 5 µs/km) | High (about 250 ms one way for GEO, so about 0.5 s round trip) | | Security | Very high; hard to tap | Low; any receiver in the footprint can receive, so encryption is needed | | Flexibility | Fixed route; new cable is needed to reach a new site | Very flexible: new site only needs a dish, mobile and remote areas are covered | | Interference | Immune to EMI | Affected by rain fade, solar interference and other transmissions | | Connectivity | Point-to-point, needs cable to each site | Broadcast and wide coverage; point-to-multipoint over a whole country | | Attenuation / errors | Very low attenuation, very low BER | Large free-space loss; higher BER | | Cost | High installation (laying), low operation | Very high satellite cost, cheap for each additional user | | Typical use | Backbone, long-haul, FTTH | TV broadcast, remote areas, ships, GPS | ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is the one-way delay of a GEO satellite link? A. About 5 µs B. About 250 ms C. About 5 ms D. About 25 µs/km Answer: B. GEO round trip is about 0.5 s; fibre is only about 5 µs/km. (Key point: Delay) 2. Why is satellite security low? A. The dish is too small B. Any receiver in the footprint can receive the signal, so encryption is needed C. Fibre is wireless D. Satellites use light pulses Answer: B. Broadcast footprint is open. (Key point: Security) 3. Which is more flexible for reaching a new site? A. Fibre: just plug in B. Both need new cable C. Satellite: only a dish is needed D. Fibre because it is point-to-multipoint Answer: C. Fibre needs a new cable route to each new site. (Key point: Flexibility) 4. What affects each? A. Fibre suffers rain fade; satellite is immune B. Both are immune C. Both suffer rain fade D. Fibre is immune to EMI; satellite suffers rain fade and solar interference Answer: D. Light in glass is unaffected by weather. (Key point: Interference) 5. Which frequency ranges are correct? A. Fibre 180-370 THz; satellite 1-40 GHz B. Fibre 1-40 GHz; satellite 180-370 THz C. Both 1-40 GHz D. Fibre 0-500 MHz; satellite 180-370 THz Answer: A. Fibre uses infrared/visible light; satellite uses microwaves. (Key point: Frequency range) ## Related in Data Communication - [Coaxial cable vs optical fiber](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Acoax-vs-fiber) — Data Communication, chapter 4 - [Transmission characteristics of guided media](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aguided-media-transmission-characteristics) — Data Communication, chapter 4 - [Short note: Multi mode optical fiber](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Amultimode-fiber-short-note) — Data Communication, chapter 4 - [Short note: Optical fiber versus STP](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aoptical-fiber-vs-stp) — Data Communication, chapter 4 - [Optical fiber advantages over coax and twisted pair](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Afiber-advantages) — Data Communication, chapter 4, asked 3× - [UTP characteristics and performance](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Autp-characteristics) — Data Communication, chapter 4 ## Related in other subjects - [Optical fiber, NA, single vs multimode](https://www.bctengineer.com/question.md?key=semester_1%2Fengineering_physics%3Aoptical-fiber-na-acceptance-mode-comparison) — Engineering Physics, chapter 6 - [Compare twisted pair, coaxial, fiber](https://www.bctengineer.com/question.md?key=semester_7%2Fcomputer_networks_and_security%3Acompare-twisted-coax-fiber) — Computer Networks and Security, chapter 2 - [Optical fiber advantages and wireless media](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Aoptical-fiber-wireless-media) — Telecommunications, chapter 2 - [Fiber optic vs copper cable](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Afiber-vs-copper-applications) — Telecommunications, chapter 2