Ground-based radio sounding of the Earth magnetosphere

A sounding link at HF established between tightly synchronized ground-based terminals located at shell conjugate sites (Jupiter, Florida, and Ushuaia, Argentina) has obtained echoes with 62 millisec delay. The echoes can be interpreted as being due to propagation along an enhancement of electron density aligned with the L=1.8 shell. The echoes are characterized by path losses 80 db worse than free space and were received at 7.46, 9.04, and 12.00 MHz for 7.6% of the over-all observing time, during night hours. Typically their strength was 15 db below noise and they were recovered with an integration time of 1 hour (3600 pulse repetition periods).