[amsat-bb] Remote sensor for antenna array orientation

[Alfred Watts]

Clayton,
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.

Regards,
Al Watts - AF5VH

-----Original Message-----
From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Clayton
W5PFG
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.

73
Clayton
W5PFG


_______________________________________________
Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available to all
interested persons worldwide without requiring membership. Opinions
expressed are solely those of the author, and do not reflect the official
views of AMSAT-NA.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb