CTU and IG CAS took the opportunity to install a fluxgate variometer instrument [4] in the already magnetically prescreened and prepared locality.
Although the noise at BDV station is very low, the used instrument (DMI fluxgate variometer) has large intrinsic noise, so actually, during the quiet night periods (with almost no electric train traffic), the PLM data are less noisy due to the used variometer.
To be able to detect, mark, and possibly remove the passing car's magnetic signature, an axial ([dB.sub.y]/dy) fluxgate gradiometer has been created in N-S direction by placing a second sensor coaxial to the variometer head.
Utilizing a "full-field" variometer, thus measuring in a feedback loop all the three vector components of the magnetic field at once, allows us for calculation of the total magnetic field (the scalar vector magnitude).
As with most gliders, it was equipped with a more traditional
variometer on its instrument panelas a back-up.
If you don't have a
variometer you can be rising and think that you are flying straight.
The variometer is the oldest and simplest instrument for monitoring the Earth's magnetic field.
The simplicity and low cost of the basic variometer are advantages but the lack of automatic recording of the output is its disadvantage.
In contrast to the variometer, the fluxgate is a much more complex, and recent (developed in the 1930s), sensor.
For this paper, a fluxgate sensor and a home-made variometer were installed in the author's study.
Speed-to-fly information is presented to the pilot by placing a speed-to-fly ring (Mac-Cready ring) around the
variometer dial, referring to a table or chart or using an electronic flight computer displaying the data.
A modern
variometer aids this process immensely, but you still have to muscle the turns.