Automatic N (h, t) Profiles of the Isonosphere With a Digital Ionosonde

A method is described to accomplish automatic data selection and profile inversion to obtain ionospheric electron‐density profiles from digitized radio soundings. The profile inversion is based upon the well‐established formulation of Paul [1960] by which the optimum radio‐frequency sounding intervals can be specified from an approximate knowledge of the profile. The expected virtual height coordinates (h') at these frequencies (ƒ) are likewise estimated, and procedures are then used to select h'(ƒ) observations nearest the predicted coordinates from a subsequent digital ionogram. From these the next profile is obtained. The process adaptively follows the changing shape and detail of the profile. The procedure requires an average of 20 sec per profile on a standard data‐processing computer and can be adapted, with benefit to on‐line real‐time use in our ‘dynasonde,’ digital ionosonde.