Billingsley Aerospace is located in Brookeville, Maryland. The facility is in a rural, magnetically
quiet location that is ideally suited for precise magnetic measurements. It consistsof a 500 square foot
"quiet laboratory" that is remote from the main building and an additional 1,800 square feet of lab and
office space. The laboratory is completely equipped for assembly and characterization of magnetic sensors.
Sensor calibration is done in a computer-controlled triaxial Helmholtz system. Field generation and data
acquisition are completely automated, eliminatinghuman error and speeding up the process by 10 to 20 times
over manual methods. An automated non-magnetic environmental chamber in the coil provides the ability to
test up to 12 instruments simultaneously over a wide range of temperatures. Measurement accuracy is assured
by regular equipment calibration in accordance with MIL-1-45208A and regular comparison to the laboratory's
proton standard.
The Billingsley Aerospace laboratory has a full compliment of state of the art, fully automated testing
equipment. Systems are computer controlled using GPIB buss and RS232C instruments. The laboratory has three
fully automated triaxial Helmholtz Coil Systems: a
1 meter and two 2.2 meter coils. Custom software, Billingsley Aerospace Automated Test System (BMATS) was developed using Labview. BMATS automatically calculates
orthogonality, frequency response and linearity of instruments;
controls temperature environments;
measures noise, and produces corresponding reports. Automated
testing expedites all facets of testing, enables the test facility to handle large production runs, and facilitates
flexible, accurate reporting.
The Helmholtz coil systems have "closed loop" servo controllers. These
controllers maintain magnetic fields exactly at the desired level, even in the presence of large changes in
the background magnetic field. These changes could be caused for a variety of reasons. Typical sources of
change would be a diurnal variation in Earth's field or the nearby movement of automobiles. If these changes
were not canceled, they would appear as errors in the instrument and reliable testing would not be possible.
Accuracy of these Helmholtz systems in maintained by regular calibration with a Proton Magnetometer Absolute
Standard.
The excellence of Billingsley's Helmholtz magnetic calibration systems has been recognized by customers
such as the NIST (US National Bureau of Standards), NPL (British Bureau of Standards), Allied Signal,
Magnavox Corp., Chrysler Corp., Digicourse Corp., Ithaco Corp., Westinghouse Oceanic, and Thomson Sintra in France.
