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Spoofing detection available on Javad GNSS OEM boards

February 9, 2018  - By

Two methods of spoofer detection, the identification and sourcing of false GNSS signals, have been released by Javad GNSS, using features available for all of its OEM GNSS boards.

  • Spoofer detection and alarm. This feature then identifies and isolates the spoofer signal, ignores it, and provides a position solution using only valid satellite signals.
  • Determination of the direction from which the spoofing signals emanate. This can aid in tracking down the actual spoofing source.

Spoofer Detection

With 864 channels and roughly 130,000 quick-acquisition correlators, the Javad GNSS Triumph chip can assign more than one channel to each GNSS satellite, in order to find all the signals that are transmitted with that satellite’s PRN code. If the chip detects more than one reasonable and consistent correlation peak for any PRN code, it concludes that spoofing is present and can the proceed to identify the spoofed signals.

In this case, it uses the position solution provided by all other clean signals (L1, L2, L5, and so on, from all GNSS constellations — GPS, GLONASS, Galileo, Beidou, and mroe) to identify the spoofer signal and use the real satellite measurement. If all GNSS signals are spoofed or jammed, then the system issues an alarm, directing the user to ignore GNSS and use other sensors in an integrated system.

Satellite and Spoofer Peaks

The figure below shows an example of a spoofer signal and a real satellite signal received at a GNSS receiver. These  screenshots  are from a real spoofer in a large city. The bold numbers are for the detected peaks. The gray numbers represent highest noise, not a consistent peak. A “*” symbol next to the CNT numbers indicate that signal is used in position calculation. Each CNT count represent about 5 seconds of continuous peak tracking.

The first screenshot shows no spoofing is present. The second shows that all GPS satellites are being spoofed.

No spoofer. Only one reasonable peak for each satellite. (Table: Javad GNSS)

No spoofer. Only one reasonable peak for each satellite. (Table: Javad GNSS)

Table: Javad GNSS

Table: Javad GNSS

In the above screenshot all GPS satellites have two peaks and all are spoofed. We were able to distinguish the spoofer signal and use the real satellite signals in correct position calculation as indicated by the ”*” next to the CNT numbers.

GNSS Overall View

The following screenshot  shows the status of all GNSS signals. The format and the signal definitions are explained below.

Table: Javad GNSS

Table: Javad GNSS

Tracked: Tracked by the tracking channels and has one valid peak only.
Used: Used in position calculation.
Spoofed: Has two peaks. Good peak is isolated, if existed.
Blocked: Blocked by buildings or by jamming. If jammed, shows higher noise level.
Faked: Satellite should not be visible, or such PRN does not exist.
Replaced: Real signal is jammed and a spoofed signal put on top of it. Because of jammer, it shows higher noise level.

For determination of the direction from which the spoofing signals emanate, see Where is that spoofed signal coming from?

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