What is GPS spoofing?

Why in News? For the first time, Delhi’s IGI Airport is facing a problem called for the last few days.
This has caused flights to be delayed or diverted, especially when planes need to land or take off in a particular direction (from the Dwarka side to Vasant Kunj).

• Because the main runway’s instrument landing system (ILS) is under upgrade, aircraft currently depend on GPS-based navigation (RNP) to land.
  But since the GPS signals are being spoofed (faked), the planes can’t rely on them — leading to flight disruptions and congestion.
  For example, several flights had to be diverted to Jaipur recently due to this issue.

What are GPS Spoofing and Jamming?

Spoofing:

• Spoofing means sending fake GPS signals to make an aircraft or GPS device think it’s in a different location.
• This tricks the GPS receiver into showing wrong position data.

Jamming:

• Jamming means blocking GPS signals by sending stronger radio signals on the same frequency.
• This makes the GPS receiver unable to get any signal at all.

Both spoofing and jamming are done using foreign radio transmitters, which can disturb normal navigation systems.

Why GPS is Easy to Spoof?

• GPS has two types of signals:
  • Military signals (P/Y code): Encrypted and secure.
  • Civilian signals (C/A code): Open and unencrypted — anyone can copy or fake them.
• Because civilian GPS signals are public, hackers or adversaries can recreate and send fake signals to confuse GPS receivers.

How to Protect Against Spoofing (Anti-Spoofing):

Use Encrypted Military Signals (SAASM Receivers):

• The safest method is using encrypted military GPS receivers called SAASM.
• These can read the secure P(Y) signals and cannot be easily fooled.
• However, these are restricted to military or government use

Use Multi-Constellation Receivers:

• Civil GPS receivers can use multiple satellite systems — GPS (USA), GLONASS (Russia), Galileo (Europe), BeiDou (China).
• If one system is spoofed, the others help cross-check and detect fake signals.

Combine GPS with IMU (Inertial Measurement Unit):

• An IMU uses sensors (gyroscope, accelerometer, magnetometer) to calculate movement without GPS.
• Even if GPS is spoofed, IMU provides accurate position for a short time.
• Spoofers can’t fake Earth’s gravity or real motion.

How to Protect Against Jamming (Anti-Jamming)?

Signal Filtering:

• Receivers can use filters to remove unwanted signals or noise that are not part of real GPS frequencies.
• Works well for out-of-band interference (signals outside the GPS frequency range).

Use IMU:

• Again, an IMU helps maintain position temporarily when GPS is jammed.
• It keeps navigation working for a few seconds or minutes without any satellite signal.

Use Smart Antennas (CRPA):

• Controlled Reception Pattern Antennas (CRPAs) have multiple antenna elements.
• They can detect the direction of interference and create “blind spots” (called nulls) towards that direction.
• This helps ignore jamming signals and continue receiving real GPS signals.

Why it Matters:

• GPS spoofing and jamming can seriously affect aircraft navigation, military operations, and even daily GPS-based services like maps, banking, and communication.
• At IGI Airport, this problem is especially serious right now because the main runway’s ILS is under upgrade — leaving pilots more dependent on GPS signals.