Abstract: Outbound signals carried over an electric power network are detected and crosstalk is rejected by sampling the waveform in three segments of each cycle. In the first segment valid signals are always absent. Valid signals appear at the same time in both the second and third segments. Sample waveform values from alternate half cycles are compared to detect differences indicative of outbound signal information. The energy in each of the three segments is compared with an energy threshold for that segment and a cycle under test is rejected when the energy in the first segment exceeds the threshold for that first segment. A cycle under test is also rejected if the energy in the third segment greatly exceeds the energy in the second segment. Signal detection thresholds for both signal strength and energy in the segments are set recursively using actual samples acquired at the outbound detection site. These thresholds are sensitive to dynamic network changes.