A fast method to determine the nose frequency and minimum group delay of a whistler when the causative spheric is unknown

Abstract

Using Bernard'S (1973) approximation of the ducted whistlers, a fast and simple method is developed for the determination of whistler nose frequency ( f n ) and travel time at the nose ( t n ) when both the nose frequency and the causative spheric are not directly identifiable on whistler spectrograms. This method requires measurements of time delays at only three frequencies with respect to an arbitrary time origin, and the formulas for f n and t n involve only simple algebraic functions. The error for f n is comparable to the error made in measuring f n visually in the case of nose whistlers, and a value of Δ t n t n of order 5 per cent or less is achievable.