The HLP-1801 is an HD/SD audio/video synchronization probe. Two SDI inputs, with embedded audio, provide lip sync error detection by measuring between a signal's origination and a selected probing point later in the signal path. This solution is ideal for playout facilities as well as multiple system operators (MSOs), which are aiming to improve the quality of their channels by performing electronic monitoring. For example, the HLP-1801 can be used between a facility's out signal and the set-top box return, or between the server out signal and the facility's out signal. Based on Grass Valley's fingerprinting technology, the HLP-1801 continuously computes fingerprints from the video and audio content for both input signals. By looking at the fingerprints, the HLP-1801 can detect content mismatch for video and each audio channel, as well as video delays and lip sync delays for each audio channel. All of this is performed without the need to tag or watermark the signals.