Measurement of ELF noise processing

This report describes non-linear processing experiments with ELF noise recorded in Norway, Saipan, and Greece. Effective noise levels, an important measure of performance for a non-linear receiver, were computed using sine-wave signals in the 42-48 Hz and 72-78 Hz bands. Although results were not optimum due to fixed (as opposed to adaptive) clip levels, notch filter effects and local sine-wave interference, they do show diurnal variations and do provide a significant increase in the available data in this frequency range.