Growing instances of GNSS signal jamming are now a concern to many industries that are almost totally dependent upon the precise timing, navigation and synchronisation capabilities that our satellite systems offer. The ease with which illegal jamming devices can be obtained and used highlights a key single point of failure for many users putting critical systems without any back-up in jeopardy. The terrestrial low frequency LORAN network in use throughout the UK, Scandinavia and parts of Europe for many years has been proven to be highly resistant to interference and jamming and is proving to be a credible back-up or compliment to satellite broadcasts. In its latest updated eLoran form it can comfortably provide resilient timing and navigation signals every bit as accurate as GPS and is now endorsed by the European Satellite Agency. Chronos Technology can offer eLoran receivers to users concerned about GNSS vulnerabilities.