Abstract: A system for analyzing a bi-directional communication path connecting a headend station to a remote station. The communication path is used for sending and receiving messages. Messages in a forward direction are sent by modulating a carrier at a forward frequency, and messages sent in a return direction are sent by modulating a carrier at a return frequency. The system includes a headend unit which sends a sign-on message in the forward direction from the headend station. The headend unit monitors the return frequency for a response message and measures a power level for signals received at the return frequency during the monitoring operation. The headend unit sends an error message in the forward direction if no response message is received on the return frequency, and the power level is greater than a threshold value. If an error message is sent, the power spectrum in a frequency range including the return frequency is measured and sent as part of the error message.