A device for registering an interference signal capable of impairing a position determination function of a radio signal receiver, in particular a mobile radio receiver or a receiver of a global navigation satellite system, having: - a receive signal strength measuring device having a first measuring antenna which is connected with it, installed on a road and designed to receive a radio signal within a radio signal frequency range, and has a first spatial receive profile, which is oriented earthward on the road or parallel to the road surface, wherein the receive signal strength measuring device is designed to measure at several time-consecutive measuring points one signal strength of the received radio signal respectively; - a receive signal spectrum analysis device having an analysis antenna which is connected with it, installed on the road and designed to receive the radio signal within the radio signal frequency range and has a second spatial receive profile, which is facing skywards from the road, wherein the receive signal spectrum analysis device is designed to determine a first analysis value of a channel spectrum characteristic of a first channel spectrum at channels of carrier signals from the radio signal received at a first analysis time and at least a second analysis value of the channel spectrum characteristic of a second channel spectrum at channels of carrier signals from the radio signal received at at least a second analysis time; and - a registration device which is connected to the receive signal strength measuring device and the receive signal spectrum analysis device and designed to compare the first analysis value with the second analysis value and to determine therefrom a channel spectrum characteristic deviation and to register the radio signal as an interference signal depending on the first analysis value and the second analysis value, if at least one of the analysis times lies in an interference signal time section in which the majority of the measured signal strengths exceeds a predetermined signal strength threshold and the channel spectrum characteristic deviation exceeds a predetermined deviation threshold. - a receive signal strength measuring device having a first measuring antenna which is connected with it, installed on a road and designed to receive a radio signal within a radio signal frequency range, and has a first spatial receive profile, which is oriented earthward on the road or parallel to the road surface, wherein the receive signal strength measuring device is designed to measure at several time-consecutive measuring points one signal strength of the received radio signal respectively; - a receive signal spectrum analysis device having an analysis antenna which is connected with it, installed on the road and designed to receive the radio signal within the radio signal frequency range and has a second spatial receive profile, which is facing skywards from the road, wherein the receive signal spectrum analysis device is designed to determine a first analysis value of a channel spectrum characteristic of a first channel spectrum at channels of carrier signals from the radio signal received at a first analysis time and at least a second analysis value of the channel spectrum characteristic of a second channel spectrum at channels of carrier signals from the radio signal received at at least a second analysis time; and - a registration device which is connected to the receive signal strength measuring device and the receive signal spectrum analysis device and designed to compare the first analysis value with the second analysis value and to determine therefrom a channel spectrum characteristic deviation and to register the radio signal as an interference signal depending on the first analysis value and the second analysis value, if at least one of the analysis times lies in an interference signal time section in which the majority of the measured signal strengths exceeds a predetermined signal strength threshold and the channel spectrum characteristic deviation exceeds a predetermined deviation threshold.