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The effect of solar activity on the Doppler and multipath spread of HF signals received over paths oriented along the mid-latitude trough

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posted on 2011-02-14, 11:15 authored by E. Michael Warrington, A.J. Stocker
Measurements of the Doppler and delay spread associated with HF signals propagating along an oblique (1440 km) path tangential to the midlatitude ionospheric trough are presented for sunspot maximum and minimum. During the day, Doppler spread is independent of solar activity, but for winter and equinoctial nights, it is very much higher at sunspot maximum. The delay spread is also generally higher at sunspot maximum for all seasons and times of day. For sunspot minimum, measurements from a second, longer path (1800 km) are also presented. The observed Doppler and delay spreads are similar for both paths. Finally, a novel method of more accurately deriving the delay spread defined by the International Telecommunication Union (i.e., the largest delay spread including all modes that have a peak power within a user-defined threshold of that of the strongest mode) from Voice of America coverage analysis program (VOACAP) predictions is presented. For the first time, the predicted values are compared with the measured delay spreads and, while there is generally good agreement at sunspot minimum, the agreement at sunspot maximum tends to be poor because the behavior of the high-order ionospheric modes (e.g., 3F2) is not well predicted by VOACAP.

History

Citation

Radio Science, 2011, 46, RS1014.

Version

  • VoR (Version of Record)

Published in

Radio Science

Publisher

American Geophysical Union

issn

0048–6604

Copyright date

2011

Available date

2011-02-14

Publisher version

http://www.agu.org/journals/rs/

Language

en

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