Systems, methods and apparatus are described for testing a data connection provided over a power supply line. A testing apparatus is coupled to a socket of the power supply line. The AC power supply line communicatively couples the testing apparatus to a communication device or another testing apparatus. The testing apparatus identifies the signal strengths of signals received by the testing apparatus and identifies the signal strengths of signals received by the communication device. The testing apparatus outputs an indicator of the first signal strength and the second signal strength to a user and this information may be utilized to detect noise or other problems in the data connection provided over the AC power supply line.