[amsat-bb] Remote sensor for antenna array orientation
awatts44 at comcast.net
Fri Feb 19 02:24:47 UTC 2016
One issue in using magnetometers for azimuth determination is the fact that
the sensitivity to bias and scale factor errors increases when crossed
instruments are used to measure the field. In a system I designed in the
past we used a single axis magnetometer and rotated it to null out the
reading. The angle to the magnetic field was measured by the angle of
rotation required. The instrument was mounted on a ~ 1 ft. plastic shaft to
isolate it from the rotation motor and other sources of error. You could
mount the magnetometer on a simple stepper motor rotator and get better
performance as the expense of some complexity. But it might be a fun DIY
project. Another thing I could offer is I do have some software which
calculates the vector field at any location from the current geomagnetic
field model which is available on the internet. But you can do just about as
well with any current aeronautical chart.
BTW - Thanks for our QSO of earlier today on AO-85.
Al Watts - AF5VH
From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Clayton
Sent: Thursday, February 18, 2016 11:58 AM
To: AMSAT-BB <amsat-bb at amsat.org>
Subject: [amsat-bb] Remote sensor for antenna array orientation
Has anyone ever mounted a mutli-axis accelerometer or a magnetic compass
sensor to their antenna crossboom for making adjustments to point of aim?
I'm currently using Hall Effect sensors but experiencing several degrees of
drift over a short period of a few days.
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