BGM-3 Interface

Posted January 21st, 2009 by dale

Joe Stennett's interface for Bell BGM-3 Marine Gravity Meters. This interface replaces the original Bell hardware which produced a BCD encoded digital output to an HP85 control computer which wrote a 9-track magnetic tape.

Joe's interface uses the four (4) Hertz clock output derived from the BGM-3's internal timebase and the output frequency (nominally 25 kHz) that is proportional to the measured gravity. It also monitors two digital error outputs.

From these inputs it generates an asynchronous serial (RS-232C) output message with the frequency and two status bits.