Great-circle and deviated-path observations on CW signals using a simple technique

A modification of the Pinwheel techniques of observing HF signals propagated over deviated paths was used over Pacific paths on 12, 18 and 30 Mc. Strip-chart records made of CW signals with directive receiving antennas rotating ten times as fast as similar transmitting antennas gave distinct records of deviated scatter signals alone or coexisting with great-circle signals. By the use of precise program timers, combined receiving and transmitting azimuths for strongest signals were obtained. Although scattering from land masses or from equatorial "spread-echo" layers seemed a possibility when scatter signals came from a relatively fixed location, most of the results examined indicated, for all frequencies, variable scattering locations on the sea, determined by skip conditions. The method, in refined form, appeared to hold promise both as a research tool and as a means of obtaining additional hours of useful propagation during failure of a great-circle mode. It was believed that the techniques should be investigated as a possible alternative or adjunct to the station-network scheme currently under consideration [13] as a means of routing traffic during arctic disturbances.