A real time apparatus for testing a DTV antenna transmitting system, wherein the DTV antenna transmitting system transmits an original signal from a DTV transmitter to a DTV transmitting antenna, is disclosed that includes a probe, wherein the probe is connected in series with the DTV antenna transmitting system, and senses signals traversing the DTV antenna transmitting system. An error detector of the testing apparatus compares the received signal to the original signal to identify the magnitude and location of errors.