Analysis and design of the new digital algorithm in receiving with twin loops and dual channels

While changing the across twin loop antennae being directional to an omni-directional antenna, to overcome the problem of the existent methods with which multi-frequency signals can not be received at the same time, a new digital algorithm of receiving very low frequency (VLF) signals for navigation under water is introduced. That is, the dual-channel digital signals are not combined in the radio frequency stage, and are combined after the orthogonal synchronization detection, and then the omni-directional receiving for the amplitude is achieved. As for the signal phase, it can be achieved from the synchronization detection result of one channel having stronger signal. The analysis and simulation results show that the design of the new algorithm is reasonable and effective, which fulfills the requirements.