Problems and Possibilities

Find the Problem

Once the interference is detected and characterized, the operator can pinpoint or geolocate the problem if multiple sensors are used as a basis for triangulation by using time difference of arrival (TDOA) techniques. As a GNSS receiver, each sensor can self-survey its own position. In order to be able to continue sampling RF data during interference which would otherwise swamp it, it is necessary to have an external timing source. For outages that last for some hours, this can be
done with a chip scale atomic clock (CSAC). NovAtel has demonstrated that mobile interference sources (both trial units and illegal jammers observed “in the wild”) can be successfully located using this technique that uses commercial-off-the-shelf (COTS) components. NovAtel focuses on the sensors, i.e. the GNSS receivers receive output logs to users to be used in their visualizations or other integrations.

Embedded with Possibilities

Defining the presence and characteristics of interference allows users to make informed choices about GNSS interference.

Then, instead of the question “Can your GNSS receiver operate effectively in GNSS-denied conditions?,” informed users might ask “Can your GNSS receiver mitigate my interference condition?”

It may be that the interference is less dramatic than an intentional jamming attack, in which case the potential solution could be as simple as filtering within the receiver. If it’s a mission-critical system that depends on precise position, navigation and timing (PNT) and you are worried about a deliberate jamming attack, then the answer might be to use all available mitigation techniques. However, for the standard tasks (such as mapping), or when the interference is known and predictable (maybe another systems is interfering with GNSS), the answer can be much simpler, less costly and less complex.