CONTENTS

Policy on Intellectual Property Right (IPR)     ii
RECOMMENDATION  ITU-R  P.1321-3     1
Propagation factors affecting systems using digital modulation techniques at LF and MF     1
Scope     1
Annex 1     1
 1     Introduction  1
2 Propagation modes  2
        2.1 Ground wave mode  2
        2.2     Sky-wave modes  2
 3     Multipath time spread  2
 4     Variability  6
        4.1     Variations of a signal in daytime  6
        4.2 Variations of a signal in daytime from place to place  6
        4.3 Variations of a signal in night-time  7
        4.4 The characteristics of excesses and fades in LF and MF ionosphere channels  7
 5     Conclusions  8
Appendix 1 to Annex 1     8
Appendix 2 to Annex 1     9