Information on the absorption effect of the ionosphere is obtained at present from hourly readings.
This does not allow sufficient detailed study of the
variations of absorption and reduces the possibility
of correlating these variations with magnetic storms,
aurora and solar flares. The present research was
undertaken in order to develop a method of continuous
recording that would enable the degree of correlation
between these events to be investigated and quantitative
relationships to be established.
In order to facilitate the recording of this
information over long periods, special receiving
methods are employed which do not require the maintenance of a transmitter, but use natural occurring
phenomena in the form of atmospherics and cosmic noise
as signal sources. The reception problems associated
with these two types of signal are investigated and a description is given of the special receiving equipment
developed to minimise these difficulties.
The published results of experimental work on
the propagation of frequencies in the region 16-100kc/s
obtained with the aid of commercial transmitters are
studied and used to derive more information from the
atmospheric recordings concerning ionospheric variations.
It is shown that the critical frequencies of the
E and F layers affect the reception of cosmic noise,
and that by proper choice of receiving frequency
in respect to these critical frequencies, irmproved
indications may be obtained of variations in