A method for identifying the terminal ID and measuring the interference level of VSAT TDMA terminals causing interference with low signal-to-noise ratio in a first or second communication link, the terminals communicating with a hub station via a first satellite on a first communication link, wherein a second satellite may be adjacent to the first satellite, the second satellite communicating on a second communication link, wherein an interference guarding device may receive signals on said first and second communication links, the interference guarding device performing the steps of: a) monitoring a frequency spectrum in signals received from said first satellite on said first communication link or from the second satellite on said second communication link, determining from said monitored frequency spectrum if any terminals communicating with the hub station via the first satellite on the first communication link are causing cross-polar interference in the first communication link or interference in the second communication link, b) determining signal power level and arrival times of interfering bursts for each terminal in said monitored frequency spectrum, c) determining the ID of the terminal that is transmitting bursts causing interference, by either - receiving a burst time plan from the hub station on the first communication link, synchronising the burst time plan with the actual transmission on the first or second communication link in order to identify the interfering terminal, and reading the ID of the interfering terminal from the burst time plan, or - demodulating and decoding the content of the TDMA signals transmitted from the terminals to the hub station on the first communication link to derive a burst time plan, synchronising the derived burst time plan with the bursts on the first or second communication link in order to identify the interfering terminal, and reading the ID of the interfering terminal from the bursts. a) monitoring a frequency spectrum in signals received from said first satellite on said first communication link or from the second satellite on said second communication link, determining from said monitored frequency spectrum if any terminals communicating with the hub station via the first satellite on the first communication link are causing cross-polar interference in the first communication link or interference in the second communication link, b) determining signal power level and arrival times of interfering bursts for each terminal in said monitored frequency spectrum, c) determining the ID of the terminal that is transmitting bursts causing interference, by either - receiving a burst time plan from the hub station on the first communication link, synchronising the burst time plan with the actual transmission on the first or second communication link in order to identify the interfering terminal, and reading the ID of the interfering terminal from the burst time plan, or - demodulating and decoding the content of the TDMA signals transmitted from the terminals to the hub station on the first communication link to derive a burst time plan, synchronising the derived burst time plan with the bursts on the first or second communication link in order to identify the interfering terminal, and reading the ID of the interfering terminal from the bursts. - receiving a burst time plan from the hub station on the first communication link, synchronising the burst time plan with the actual transmission on the first or second communication link in order to identify the interfering terminal, and reading the ID of the interfering terminal from the burst time plan, or - demodulating and decoding the content of the TDMA signals transmitted from the terminals to the hub station on the first communication link to derive a burst time plan, synchronising the derived burst time plan with the bursts on the first or second communication link in order to identify the interfering terminal, and reading the ID of the interfering terminal from the bursts.