Download the KSS32-M handout

KSS32-M brief description

The BGGS Gravitymeter KSS32-M offers many advantages:

• High precision instrument. Accuracy better than 0.5 mGal.
• Very low drift.
• Worldwide measuring range.
• Straight line sensor without Cross-Coupling effect.
• Possibility of highly accurate and linearized measurements for up to 0.23 g (230 000 mGal) of vertical acceleration.
• Short recovery after profile changes if navigation data are available.
• Valuable readings during turn-manoeuvre if accurate navigation data are available.
• Operation at different sea states will be ensured by selection of appropriate filtering. Measurements are made possible even at rough sea conditions.
• Safety precautions for sensor and gyro platform in case of power breakdown.

The entire system can be operated and controlled via a standard computer/notebook and the BGGS application software DACQS2 :

• Start-up procedure.
• Run-down procedure.
• Safety routines.
• Application of parameters.
• Permanent system tests.
• Display and visualization of monitor data and status.
• NMEA-link to navigation and other marine instruments.
• Data from echo-sounder (if available).
• Data from magnetometer (if available).

Technical Data

Accuracy, during straight course

Vertical Acceleration	Dynamical¹ (RMS)	Effective² (RMS)
less than 15.000 mGal	0,5 mGal	0,2 mGal
15.000 – 80.000 mGal	1,0 mGal	0,4 mGal
80.000 – 250.000 mGal	2,0 mGal	0,8 mGal

Accuracy, during turning manoeuvre

Vertical Acceleration	Dynamical¹ (RMS)	Effective² (RMS)
less than 15.000 mGal	2,5 mGal	2,5 mGal

¹ Accuracy without data processing
² Accuracy after data processing

Sampling	1 reading per second
Drift rate	3 mGal/month
Range	20.000 mGal (worldwide)
Accuracy of Scale Factor	0.5%
Platform Roll	+/- 40°
Platform Pith	+/- 40°
Power Supply	100 -230 Vac / 50 – 60Hz
Power rating	400 VA max.
Environment	Temperature: +10°C to +35°C Gradient of Temperature: <2°C per hour Humidity: 30% to 70 %

KSS32-M system overview

Function principle of sensing element

Straight Line Sensor GSS32

The axially symmetric spring-mass arrangement at the STRAIGHT LINE SENSOR of the BGGS KSS32(-M) gravimeter is shown schematically.
A 36g TUBE-MASS is constrained to move vertically, so in contrast to a horizontal beam system, the sensor is essentially not influenced by cross-coupling between horizontal and vertical accelerations, e.g. of the vessel. The displacement of the tube is measured by a CAPACITIVE TRANSDUCER at the top. Motion is minimized by a feedback loop consisting of two windings of a COIL moving in the field of a strong permanent MAGNET at the bottom of the tube.
Gravity changes are derived from currents generated in the moving coil.

KSS32M in action

The following videoclip shows the system in action, the sensor being perfectly stabilized in a simulated (roll axis only) marine environment: