Survey of In-Car Jammers - Analysis and Modeling of the RF Signals and IF Samples (Suitable for Active Signal Cancelation)

Innovative distance based charging (DBC) systems for road user charging (RUC) or pay-as-you-drive insurances charge their users on the mileage recorded. The primary sensor therefore is GNSS. GNSS allows the charging system a high degree of flexibility, but is also very vulnerable due to its low signal power. It is the weakest point of the charging system, which can be target for possible fraud attempts. This brings so called in-car jammers in place. In-car jammers are small devices, powered from the cigarette lighter of a car, transmitting a high power signal within the GNSS frequency band. Thereby, they are blocking the signal reception not only in the targeted GNSS receiver, but also in its vicinity and degrading the position determination, proportional to the distance, over a wide area. To understand how serious the real threat of these jammers is, seven devices were analyzed in the frequency and time domain. With this knowledge, mathematical models are derived, which support the development of mitigation technologies. Finally, a novel mitigation approach called “Active Signal Cancellation” will be introduced.