Method and device for monitoring a mobile telephone repeater

A method of monitoring a mobile telephone repeater of the kind having two antennas and two links therebetween, said two links comprising an uplink for amplifying signals from a mobile telephone to a base station and a downlink for amplifying signals from said base station to said mobile telephone, said two links being provided with a number of amplifier chains each being designed to pass through a specific signal frequency channel or frequency band, a stability test being performed for each amplifier chain in one of said two links, wherein a possible continuous and strong signal, being caused either by an instability involving a positive feed back between said two antennas or by a disturbing signal, is detected by applying a test criterion which includes measuring a signal level and checking whether the measured signal level exceeds a threshold value, whereupon an amplifying gain in the respective amplifier chain is adjusted in response to the result of the stability test, wherein the test criterion further comprises the step of measuring the proportional time during which the input signal level exceeds a threshold value during a measuring period and checking whether said proportional time exceeds a major predetermined portion of said measuring period.