Some measurements of the propagation of HF radio signals over high latitude paths with special reference to FSK data transmissions

The high latitude ionosphere forms a highly dynamic and disturbed medium which can severely affect HF radio signals propagating through these regions. Not only is the range of frequencies over which the signal may propagate affected, but the characteristics of the propagating signals may be severely degraded, leading to, for example, an increase in the bit error rate of a digitally coded message. In order to investigate the characteristics of this type of propagation a frequency agile transmitter has been installed north of the auroral oval at Clyde River on Baffin Island in the Canadian North West Territories. Several receiving and data logging systems have been deployed at various sites to provide a variety of trans-auroral oval paths together with one path contained entirely within the polar cap. Four one-month experimental campaigns have been conducted at different times of year during which measurements of the variations in signal strength, the Doppler spread imposed on the signal by the reflection process, the selective fading between the two frequencies of an FSK data transmission and the bit error rates were undertaken. Preliminary results obtained from the FSK measurements undertaken during the summer period are presented