A System for Automatic Time Synchronization Based on the Timing Capability of the LORAN-C Navigational Network

摘要

New concepts in dealing with the circuitry for Loran-C automatic timing systems are described. The conventional analogue techniques associated with phase shifting networks have been replaced by an incremental digital phase shift device. The format identification and decoding equipment together form a system which takes into account the information of every Loran-C pulse. Owing to the use of digital signal treatment the synchronization accuracy is limited only by the resolution of the incremental phase shift. The automatic cycle selection device is based on sampling techniques where the derivative of the envelope is calculated. The system includes an epoch monitor, receiving an initial time information from a local digital clock which has to be accurate to within + or - 20 microseconds. The time of coincidence has to be precalculated and fed into the thumbwheel memory of the epoch monitor, which is automatically initiated when the synchronizing operations are concluded. (Author)