KSS32-M

The Marine Gravity Meter KSS32-M is a high performance instrument designed for marine geophysical research projects, including oil prospecting and basic research worldwide. Straight line technology together with the best precision mechanics and state of the art electronics enable highly accurate gravity measurements. As a marine Gravity Meter it is free from any Cross-Coupling errors.

Several embedded microprocessors together with sophisticated software programmes provide very easy handling. Important corrections, like Eötvös-effect and curve compensation can be applied in real time. Data from the ship’s navigation system can be fed into the Gravity Meter by interfaces. The instrument is furnished with a variety of interfaces to connect to other instruments and to have their data stored. The software includes a number of digital filters to apply to the data. The software offers corrections of the free-air and Bouguer anomalies. In case of a problem the entire system will be turned off and arrested to protect the measuring system even in severe sea conditions.

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 DACQS:

  • 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
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: less 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.