The BE Pilot Sync Option is intended for FXi or digital exciter customers building Single Frequency Networks (SFN) or simulcasting situations. The pilot of multiple transmitters on the same frequency needs to be synchronized with each other to minimize distortion or interference at the receiver during the transmitter capture period when the receiver is going from one transmitter coverage area to another.
Receivers will lock into the nearest (strongest signal) transmitter and continue receiving from that transmitter as long as the signal strength is the strongest available. Receivers in areas that have two strong signals or are in a moving vehicle that going further away from one transmitter and closer to another will benefit from Pilot sync. Receivers will switch to the stronger signal or “capture” the signal and lock onto it. If the pilots are not synchronized, the receiver will have interference when the two pilot signals can cancel each other out. To minimize this occurrence, all pilots in that SFN are synchronized so the capture is not interrupted. Syncing the pilot is one aspect of building a single frequency network. The carrier and the audio must also be synchronized independently for the pilot.
To synchronize the pilots, all transmitters in the SFN will need the Pilot sync option and will be time aligned to a GPS 1pps signal so that they will have a reference signal to align with. With the optional board, the pilot from the exciter is compared in time to the 1pps signal from a GPS receiver and removes one or multiple edges each second from a 10MHz reference signal.