CONTENTS

1     Background
 2     Introduction
 3     Survey of bands below 20 kHz
        3.1     Allocations in RR Article 5 before WRC-12
        3.2     Radionavigation systems
                  3.2.1     Omega
                  3.2.2     Alpha system (RSDN-20)
        3.3     Meteorological aids systems
        3.4     Fixed and maritime mobile systems
        3.5     Standard frequency and time signal
 4     Spectral analysis of ATD receiver locations
 5     Summary