Un sistema automatico per la misura di tre componenti del campo geomagnetico utilizzante un magnetometro a precessione nucleare

Abstract

Recording in digital form from the start is almost a necessary step in
Geomagnetic Observatories; we propose in this paper a simple method
based on the use of a proton precession magnetometer equipped with two
Helmholtz coils. A small microprocessor has been used to transform
the signal frequency measured by the electronic counter to obtain the
components absolute values and to automatize the set of measures.
A sophisticated equipment for the current generation and control was
necessary to maintain the current flowing in the Helmoholtz coils within
2 [iA for successive measurements. To maximize the signal coming from
the sensor inside the coils, for the different components, a simple arrangement
of two ortogonal small coils in only one sensor has been made.
The system proposed can furnish a very good stability and accuracy
(~ 1.5 riT) in the measured components (H, D, Z) and could avoid the
absolute measurements.
The time sampling for the complete set of components is ~ 20 sec;
the instrument can be used then to obtain informations of the geomagnetic
variations with period T > 1 min. The Observatory use is
suggested for an automatic hourly means computation.