Sounding principles for high latitude BLOS HF channels


  1. Willink, T.J.
Corporate Authors
Defence Research and Development Canada, Ottawa Research Centre, Ottawa ON (CAN)
Beyond-line-of-sight (BLOS) HF communication propagates via the ionosphere; this atmospheric layer is disturbed by geomagnetic activity, causing the received signal to be distorted by Doppler fading and shift. In polar and auroral regions, these Doppler effects can be quite severe, affecting the reliability and robustness of communication links. Temporal dispersion causes multipath spread on each mode, and multiple modes may be observed resulting from reflection at different ionospheric layers and/or multi-hop paths that include reflection from the Earth. The propagation parameters are quite dynamic, with trends observed diurnally, seasonally and over the multiyear sunspot cycle, and vary by operating frequency. To design and evaluate radio technology for these conditions, it is necessary to characterise the propagation parameters on a variety of communication links at different times. Measurement campaigns to obtain the relevant ranges of parameters require carefully-designed channel sounders. Pseudo-noise sequences with pulse-compression characteristics are suitable for extracting the channel responses with a minimal amount of signal processing. Herein, several periodic and aperiodic pseudo-noise sequences are evaluated over a wide range of propagation conditions, obtained from previous high-latitude sounding campaigns. It is found that short aperiodic sequences are the most reliable selection: although they have limited processing gain, they are short enough to limit disto

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HF communications;BLOS;propagation
Report Number
DRDC-RDDC-2018-D122 — Reference Document
Date of publication
01 Nov 2018
Number of Pages
Electronic Document(PDF)

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