GEOfba200 Force Balance Accelerometer

  • Low noise accelerometer for high precision and high dynamic range
  • Selectable full scale range +/-4g to +/-0.25g standard, higher gain set custom available
  • Wide passband DC to 215Hz, higher corner frequency custom available
  • Simple installation using a central fix bolt
  • Electronically adjustable DC offset
  • Power 9-18Vdc, 1.2W
  • Waterproof IP68 aluminum or stainless-steel casing

The GEOfba200 is a very low-noise triaxial force-balance accelerometer with a large dynamic range, suitable for seismology, hazard mitigation and civil engineering applications. The instrument has both a flat response to ground acceleration from DC to 215 Hz and a stable phase response within the passband. Output range is 40Vpp differentially and supports variety range of gain sets from +/-4g to +/-0.25g in the standard configuration and availability for higher gain set under request.

Due to it’s high dynamic range which exceeds 155dB the sensor provides from on-scale recording of earthquake motions to structural seismic noise monitoring and allows engineers to study motions at higher frequencies. The sensor allows easy field calibration through its calibration line.

GEOfba200 sensing element mechanism

Inside the GEOfba200 there are three similar accelerometers, orthogonally placed. The sensor is operating according to the force-balance principle as closed-loop sensor (servo accelerometer).

The motion of the seismic mass is monitored from a very sensitive capacitive transducer and a very low noise VHF preamplifier. The demodulator generates in-phase and low noise seismic signal which is fed back to the seismic mass through a phase compensator, a power amplifier and a fully symmetrical force actuator consisting of a double coil-magnet system. This design eliminates any non-linearity due to lack of symmetry. The output amplifier sets the selectable acceleration gain between +/-4g to +/-0.25g.

GEOfba200 block diagram

GEOfba200 self-noise

Red: 4g, Orange: 2g, Yellow 1g, Green 0.5g, Blue 0.25g

GEO-A200 Compact Digital Accelograph

  • FBA based compact digital accelerograph
  • Cost effective and high performance
  • Bandwidth DC-200Hz
  • Dynamic range >155dB
  • Ethernet - WiFi - Serial port
  • 32bit ADC digitizer
  • GNSS time/Precision DPLL
  • 0.1-1000 samples per second
  • LCD and six status LEDs
  • Integrated Seismic Switch
  • Embedded open-source OS
  • Embedded seedLink server
  • Embedded earthworm server
  • Continuous and trigger recording
  • Advanced networking functionality
  • Smart seismic network operation

GEObit introduces GEO-A200 high resolution and high dynamic range compact digital accelerograph. The size of the instrument is only 139mm heigh and 138mm diameter. The power consumption is less than 2W. Available sampling rate is 1 to 1000sps and optional lower sampling rates are supported. Built-in GNSS receiver combined with ultra accurate DPLL unit providing time drift 10e-9sec ensures timing stability even in the absence of GPS signal. NTP timing is also available. The instrument provides self calibration functionality. DC offset removal is also perfomed automatically or on demand. Acquisition parameters and operation modes can be set from the user-friendly web interface, which can be protected with up to up to 64 characters passwords.

The unit operates in continuous mode, triggered mode or both and data are streamed through different data ports. Local data storage is selectable as well as logfile information. The unit supports advanced functionality, implemented from the combination of trusted open source software components. Because of open source architecture it is able to run any custom application, thus providing the next day solution to the user. The hardware is based on an embedded ARM9 400MHz ARM linux board running 14.6 linux kernel. The data are stored in mini-SEED format into the microSD card or to a removable USB stick. The instrument supports 10/100 ethernet port and debug port. FTP, SFTP, SSH are also available. The state of health is transmitted over UDP packets upon request.

The instrument supports embeded earthworm and seedlink server with configurable data packet size that allows data transmission with low latency. The instrument is ideal for earthquake monitoring, early warning applications and structural monitoring applications. Single bolt mounting and flexibility of connectivity allows easy and quick installation.

GEO-S120 Broadband Seismic Sensor

  • 3 component broad-band seismometer
  • Force Balance with capacitive transducer
  • Surface or shallow burry installations
  • 150mm diameter, 125mm height
  • Aluminium or Stainless Steel casing
  • Bandwidth 120sec - 80Hz or 60sec-90Hz
  • Sensitivity 1200V/m/s
  • Power consumption < 1W
  • Automatic mass center
  • Self-noise 80sec-16Hz below NLNM
  • Dynamic range > 155dB @1Hz
  • Operation Range: -20 +60°C

The GEO-S120 broadband seismometer is a product rely on years of experience in designing high precision, low noise, and reliable seismic equipment. Based on a very sensitive capacitive transducer that monitors the position of the seismic bass and a feedback loop that generates signal output proportional to velocity with extended bandwidth 120sec to 80Hz. The instrument has low self-noise so it is ideal for local, regional and teleseismic earthquake recording. No mass lock is required and supports automatic mass centering. The sensor provides calibration input and communication via serial port. The GEO-s120 design is exceptionally versatile, ideal for both direct bury and vault use cases. The seismometer casing is made from hard anodized aluminum or stainless steel.

When combined with our GEOthree or GEOsix datalogger the GEO-S120 provides a true broadband station with low overall power consumption, providing an ideal solution for rapid response applications that require high-resolution data. The GEO-S60 version of this seismometer has equal specifications but the output velocity response is flat between 60sec to 90Hz.

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