LaCoste
& Romberg LLC
The first name in gravity
since 1939
MVR FEEDBACK
SYSTEM MANUAL
CHAPTER 4
GRAVITY SURVEYING
MICROGRAVITY SURVEYING (LESS THAN 2 MGAL)
If you wish to perform a
microgravity survey within about a 2 mgal range, set the MVR
system power supply voltage to 10 volts. You can clamp the dial
in one place and simply record the Feedback Voltage output at
each station. The calibration factor is then used to convert
measured voltage differences to gravity differencess. One
advantage of this form of surveying is that NOT turning the
nulling dial eliminates any source of circular error when making
a gravity measurement.
SURVEYING OF GRAVITY DIFFERENCES GREATER THAN 2 MGAL
For standard point-to-point
measurements of gravity differences, set the MVR system power
supply voltage to 30 volts. Remember that when using MVR
Feedback, the beam is ALWAYS being forced to the reading line,
provided the nulling dial is set within the approximately 2 or 20
milligal range of the system. Turning the nulling dial causes the
Feedback card to adjust the force required to KEEP the beam at
the reading line.
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© 1998 LaCoste and Romberg LLC