Examples of results from a dual satellite (GEOS-1 and ISEE-1) study of terrestrial non-thermal electromagnetic continuum radiation are presented. The problems of sources and generation mechanisms are discussed in the context of simultaneous measurements of radiation arrival directions, radiation cut-offs, and detailed spectral observations. The results, which imply significant contributions from the magnetospheric volume to the low frequency ('trapped') component, confirm the near-plasmapause as the source of the higher frequency ('escaping') component. The detection of significant X mode radiation and the implied presence of localized non-directive sources lead us to conclude that current theories of generation are inadequate.