Question
Which of the following statements with regard to drone swarms is/are correct?
1They use Terahertz band of frequency to communicate with the command centre.
2Individual drones in the swarm can communicate with other drones in the swarm.
3GPS Spoofing is a commonly used technique to counter drone swarm attack.
A1 only
B2 and 3 only
C1 and 2 only
D1, 2 and 3
Statement 1 Context — What Frequencies Drone Swarms Actually Use
✅ Actual Drone Swarm Communication Frequencies
UHF (Ultra High Frequency) · VHF (Very High Frequency) · 2.4 GHz and 5.8 GHz ISM bands (Wi-Fi/radio control) · S-band · L-band · SATCOM for long-range · Mesh radio networks for inter-drone comms
❌ Terahertz (THz) — NOT used in drone swarms
Severe atmospheric attenuation (absorbed by water vapour) · Very short range (~10m) · Cannot penetrate obstacles · Currently experimental for 6G networks · Not deployable in operational drones
Each Statement — Verified
1
“They use Terahertz band of frequency to communicate with the command centre” — FALSE
Drone swarms use conventional radio frequency (RF) bands — NOT Terahertz:
“Terahertz band to communicate with command centre”
✗ Wrong — THz is experimental, not operational
Current operational drone swarm communications:
• UHF/VHF bands — standard military drone command and control links
• 2.4 GHz and 5.8 GHz ISM bands — commercial drone control and inter-drone communication
• S-band and L-band — longer-range military data links
• SATCOM — for beyond-line-of-sight operations
Why Terahertz (0.1–10 THz) cannot work for drone-to-command comms:
• THz waves are strongly absorbed by water vapour and oxygen in the atmosphere → range limited to ~10 metres outdoors
• A command centre might be kilometres away — THz signal would be completely absorbed well before reaching it
• THz technology is in early research/lab stages, being explored for 6G millimetre-precision sensing and ultra-short-range communications
• Some researchers are exploring THz for close-proximity inter-drone links, but even that is experimental
✗ Drone comms = UHF/VHF/2.4GHz/5.8GHz, not THz
THz range in open air = ~10 metres maximum. Command centre could be km away. THz = 6G lab research. Not used in any operational drone swarm.
2
“Individual drones in the swarm can communicate with other drones in the swarm” — TRUE
This is the defining characteristic of a drone swarm — what distinguishes a swarm from a simple collection of drones flying together:
Individual drones communicate with other drones in the swarm
✓ Correct — defining feature of a swarm
• Drone swarms use decentralized collective intelligence — no single central computer controls every drone’s every movement
• Each drone continuously communicates with neighbouring drones via ad-hoc mesh networks
• Inter-drone communication enables: collision avoidance · formation maintenance · mission coordination · real-time tactical adaptation
• If one drone is lost (jammed/shot down), the swarm re-configures around the remaining drones — no single point of failure
• This is inspired by the collective intelligence of birds (murmuration), fish schools, and insect swarms
“A collection of drones flying in the same area is NOT a swarm. A swarm is a software-defined collective where individual vehicles operate as components of a unified system.”
✓ The very definition of a swarm
Inter-drone mesh communication → decentralized swarm intelligence. Each drone shares spatial data, coordinates paths, avoids collisions without central control.
3
“GPS Spoofing is a commonly used technique to counter drone swarm attack” — TRUE
GPS Spoofing is a primary Electronic Warfare (EW) counter-drone technique:
GPS Spoofing — common counter-drone swarm technique
✓ Correct — standard Electronic Warfare tool
How GPS Spoofing works against drones:
• Broadcasts false, high-power GNSS (GPS) signals that override legitimate satellite signals
• The drone’s navigation system believes the false signals → thinks it is at a different location
• Results: drone flies off course · mid-air collision with other swarm members · forced landing in wrong location · return-to-home triggers landing at wrong “home”
Why especially effective against swarms:
• Entire swarm relies on GPS for coordinated navigation → one spoofing attack can disorient all drones simultaneously
• Swarms depend on precise GPS positioning to maintain formation and avoid collisions → GPS denial causes swarm cohesion to break down
India’s Indrajaal counter-drone system explicitly lists GNSS spoofing as one of its capabilities alongside RF jamming and cyber takeover.
✓ Standard C-UAS electronic warfare tool
GPS spoofing = false GNSS signals → drones navigate to wrong locations → swarm breaks down. Used by India’s Indrajaal, US CUAS systems, and military anti-drone systems worldwide.
Drone Swarms — Key Facts for UPSC
| Parameter | Detail |
| What is a drone swarm | Multiple drones operating as a coordinated collective · Decentralized AI — no single control node · Inter-drone mesh communication · Inspired by swarm intelligence (birds, fish, insects) |
| Communication — actual | UHF · VHF · 2.4 GHz / 5.8 GHz ISM · S-band · L-band · SATCOM · Ad-hoc mesh radio networks for inter-drone links |
| Terahertz (THz) | 0.1–10 THz · 6G lab research stage · ~10m outdoor range (water vapour absorption) · NOT used in any operational drone swarm · Statement 1 is wrong |
| Counter-drone (C-UAS) techniques | RF jamming · GPS spoofing · Electronic takeover · Directed energy (lasers) · Kinetic interceptors · Net guns · High-powered microwave |
| GPS Spoofing | Broadcasts fake GNSS signals → overrides real GPS → drone navigates to wrong location → swarm coordination collapses |
| India — counter drone | Indrajaal system (Bengaluru company) · Ranger vehicle-based CUAS · DRDO anti-drone systems · Used at critical infrastructure and airports |
| India — drone swarms | India set world record with drone light show at Republic Day 2023 (3,500+ drones) · Defence Research (DRDO) developing military drone swarms · Skyroot, ideaForge, Tata Advanced Systems active |
Memory Trick
🧠 Remember It This Way
Statement 1 trap — Terahertz sounds futuristic = must be advanced drone tech: The opposite is true. Terahertz is so short-range (10 metres in open air) that it’s useless for command-centre communication. Drone comms need range — UHF/VHF/SATCOM provide it. THz is a 6G lab concept, not a drone technology.
The “swarm” definition = inter-drone communication: A flock without communication = just drones flying together. A true swarm = drones constantly talking to each other via mesh networks. Statement 2 describes the essential feature that makes a swarm a swarm.
GPS Spoofing = trick the navigator: GPS spoofing sends fake “I am at location X” signals stronger than the real GPS. The drone believes the fake. Think of it as hacking the drone’s internal GPS — it lands where YOU want it to, not where the operator wants. Particularly devastating against swarms because the entire formation relies on GPS.
