Designing a Ranging Signal for use with VDE R-Mode

Kurzfassung

As GNSS signals are not always reliable and subject to jamming and spoofing, it is desired to have alternative means of maritime navigation. One approach for that is to equip communication systems on the shore with the option to transmit ranging signals (R-Mode), which vessels can use to determine their position. The VHF Data Exchange System (VDES), which is currently in standardization, can be utilized for this R-Mode application. For that purpose, a ranging signal has to be chosen that will provide good time of arrival estimates. By using the Cramér-Rao-Bound (CRB) and the Ziv-Zakai Bound (ZZB), we investigate different options of the ranging signal. We find that optimising for high bandwidth is desirable at high Signal to Noise Ratios (SNR), while optimising for low autocorrelation sidelobes is desirable at low SNRs. By utilizing a combination of both options, we are able to find a suitable ranging signal for any given SNR.