CONTENTS

 1     Introduction
 2     Location of control points
 3     Basic and operational maximum usable frequencies
        3.1     Basic maximum usable frequencies
        3.2     E-layer critical frequency (foE)
        3.3     E-layer basic MUF
        3.4     F2-layer characteristics
        3.5     F2-layer basic MUF
                  3.5.1     Lowest-order mode
                               3.5.1.1     Paths up to d_max (km)
                               3.5.1.2     Paths longer than d_max (km)
                  3.5.2     Higher-order modes (paths up to 9 000 km)
                               3.5.2.1     Paths up to d_max (km)
                               3.5.2.2     Paths longer than d_max (km)
        3.6     The path operational MUF
 4     E-layer maximum screening frequency (fs)
 5     Median sky-wave field strength
        5.1     Paths up to 7 000 km
                  5.1.1     Modes considered
                  5.1.2     Elevation angle
                  5.1.3     Field strength determination
                  5.1.4     Time delay
        5.2     Paths longer than 9 000 km
        5.3     Paths between 7 000 and 9 000 km
 6     Median available receiver power
 7     Monthly median signal-to-noise ratio
 8     Sky-wave field strength, available receiver signal power and signal-to‑noise ratios for other percentages of time
 9     Lowest usable frequency (LUF)
10     Basic circuit reliability (BCR)