Loran-C measurement trials in Ireland and U. K. : interference, noise, and field strength results

A program of measurements is reported that has confirmed that carrier-wave interference is the key factor controlling Loran-C signal-to-noise ratio in Northwest Europe. The tests, held at eight sites in Ireland and the UK, identified 68 interfering signals, 17 of which exceeded the worst-case atmospheric noise. Many interferers were synchronous with Loran-C spectral lines. Especially prominent among the most serious interferers were Decca Navigator signals. The paper discusses the need for efficient filtering techniques and, where notch filters are used, the development of strategies to balance the conflicting claims of high-powered, wide-area interferers with those of the many low-powered Decca stations