AIM+ GNSS jamming protection

GNSS interference and protection: How to counter radio frequency GPS/GNSS interference (interference suppression)?

One of the core pillars to ensure the reliability of Septentrio GPS/GNSS receivers is AIM+technology. This patented technology called "Advanced Interference Monitoring and Mitigation" is already embedded in every of our receivers. It not only resists radio interference, but also protects the receivers from intentional GNSS interference suppression and deception attacks.

GNSS interference occurs when GNSS signals with already low power are covered by other wireless signals at the same frequency. This situation may occur when the GNSS receiver is close to other electronic devices (please also read the insights on "anti-interference drones" and "self interference"), radio antennas, or modems. Wireless enthusiasts sending radio signals nearby may inadvertently cause GNSS interference. This interference may reduce positioning accuracy and even cause the receiver to completely lose real-time dynamic positioning (RTK) or acquisition of position, velocity, and time (PVT).

In rare cases, interference is intentionally created to interfere with the operation of unprotected GPS receivers. Illegal interference suppression equipment can disable GPS receivers within a radius of several hundred meters.

GPS/GNSS interference suppression equipment

Interference suppression equipment is sometimes used by truck drivers to avoid road tolls. This type of GPS interference suppressor will disable the GPS units on the truck, but it will also affect other nearby GPS devices. These interference suppressors can now be purchased online at increasingly lower prices.

What is GPS/GNSS spoofing?

Deception is an intelligent form of GPS interference. In deceptive attacks, The GPS receiver will report an incorrect location as it has received a GNSS signal intentionally sent by a third party containing incorrect positioning information. For more information on deception and how to combat it, please refer to relevant materials.

Utilizing AIM+ for Detecting and Counteracting GNSS RF Interference

AIM+ technology serves as a powerful tool in detecting and counteracting radio frequency (RF) interference, ensuring swifter setup, minimized downtime, and secure operational performance. This advanced technology safeguards against both simple narrow-band interference and more intricate wide-band interference scenarios, including jamming and spoofing attacks.

Through your receiver's web interface, you can leverage the spectral plot to analyze interference, enabling you to determine the type of interference and its potential source. AIM+'s capabilities are such that it cannot even be deceived by advanced GNSS signal generators like the Spirent GSS9000. With realistic power levels and actual navigation data embedded in the signal, AIM+ can identify it as a "non-authentic" signal, ensuring the integrity of your positioning data.

Narrow-band GNSS/GPS interference, often caused by electronic devices, typically affects only a small segment of the GNSS frequency spectrum. To mitigate its effects, AIM+ offers the option to configure three notch filters in either automatic or manual mode. These filters effectively eliminate a narrow portion of the RF spectrum surrounding the interfering signal. Notably, the L2 band, which is open for use by radio amateurs, is particularly prone to this type of interference.

Moreover, the effects of intentional or unintentional wideband interference can be addressed by activating the WBI mitigation system. This system, more effectively than traditional pulse-blanking methods, reduces the impact of pulsed interferers, ensuring the continued reliability of your GNSS positioning system.

GNSS RF Interference Mitigation by configuring the notch filters

When configuring notch filters for GNSS RF interference suppression, in the default automatic mode of the notch filter, the receiver will automatically suppress interference in the affected spectral area. In manual mode, as shown in the above figure, for Notch1 configuration, the affected spectral area is identified by specifying the center frequency and bandwidth, and is effectively shielded or "blank" by a notch filter.

Wideband interference mitigation

The inadvertent use of military and civilian ranging and communication devices can induce wideband interference in GNSS signals. Additionally, intentional sources like chirp jammers also pose a threat. The wideband interference mitigation system (WBI) effectively diminishes the impact of both unintentional and intentional interference on GNSS signals.