Random voltage changes on bus lines may lead to reading corrupted digital data. A novel methodology for detecting such anomalies is proposed. It uses multiple threshold voltages at the receiver end. In earlier work it was shown that multiple voltage thresholds improve the performance along buses, especially when they are coupled as is often the case in deep-submicron. This work shows that multiple thresholds can also be used to identify voltage perturbations online. The mechanism is assessed on bus lines that may have up to two adjacent aggressors. The efficiency of the methodology is evaluated for perturbations at single and multiple receiving nodes of a data bus.