Transition to Referenced Mode
The system starts up in Non-Referenced Mode, and is continuously looking for a valid Reference Audio file by measuring frequency and amplitude of the received over-the-air audio. Transitioning to Referenced Mode requires the successful detection of a TestID tone sequence of proper frequencies, and durations.
Once the Referenced Mode state is achieved, the expectation is that all tones encountered will conform to the script identified by the collected Test ID digits. The system remains in the Referenced Mode state until either the end of test is reached, or a loss of synchronization occurs (see "Synchronization Lost Event" and "Synchronization").