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.

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

GEOwarning, Early warning accelerograph

GEOwarning is a compact, ultra-low-cost digital accelerograph.  It integrates 3 axes MEMS accelerometer, 20bit digitizer, embedded linux OS and GPS or NTP timing. Seedlink and Earthworm servers ensure reliable real time data telemetry while large storage volume ensures a long period of local data recording. The instrument has very low power consumption so it can operate powered from a small 12Vdc battery. Due to its small size and its flexibility of communication (Ethernet or WiFi) and timing (GPS or NTP), it can be easily installed at buildings and other structures.  The device supports a software configurable, variable range of +/-2g, +/-4g, +/-8g presenting an ideal solution for a wide range of structural monitoring and early warning applications. Minimum data latency along with the calculation of an earthquake’s Cumulative Absolute Velocity (CAV) guarantee that the user can be immediately alerted just at the beginning of the event. Compact design is a competitive advantage and this is reflected in the price which is only a small fraction of the typical commercial accelerograph’s cost. The user is now able to deploy even five times more units for the same budget.

  • 3 components miniature Accelerograph
  • Range +/-2g, +/-4g, +/-8g
  • Low power consumption
  • Ethernet and WiFi
  • Dimensions 90 X 115 X 55 mm
  • 20bit analog to digital converter
  • Embedded Seedlink and Earthworm Server
  • Realtime Telemetry and Local Storage
  • MiniSEED data format
  • Linux OS
  • Web Configuration Interface
  • SPDT relay, software configurable
  • Dynamic Range 97dB
  • Operation Range: -20 +70 C
  • Waterproof IP67 Aluminum Case

The SM1500 & SM550 Strong Motion Acceleration Sensors (Accelerometers)

  • 3-axis accelerometers
  • Low Power Consumption
  • Surface/wall mounting
  • MEMS (Force balance / ASIC technology)
  • DC – 750Hz, DC-2.4kHz
  • Wide Dynamic Range up to 116dB
  • Output range +/-2g to +/-12g linear
  • Noise level up to 0.7ugrms/sqrt(Hz)
  • Operating temperature -20 to +70oC
  • Borehole type (optional)
  • 4-20mA current loop output – NEW!

The SM550 and SM1500 are two MEMS type, three-component acceleration sensors. Both have wide frequency response. The SM1500 model provides response from DC to 550Hz, while the SM550 model provides response DC to 2.4kHz. Many output ranges are available for both models like +/-2g, +/-4g, +/-5g, +/-6g, +/-10g, +/-12g, are. Default sensitivity is 2.4V/g for the SM1500, and 0.8V/g for the SM550.

The SM1500 and SM550 accelerometers technology is based on a variable capacitor transducer and a feedback circuit that operates in a closed-loop configuration. The feedback force is controlled by an application-specific integrated circuit (ASIC) which provides high reliability and low output noise.

The SM1500 and SM550 sensors operate from a 12Vdc power supply that can range from 9Vdc to 18Vdc. The typical power consumption is 18mA

Acceleration output is differential analog, swinging between +/-5V. Other output voltages are available.

4-20mA current loop output is also available for both sensors

The default cable length between the sensor and the digitizer is approximately 2 meters but it can be extended. The 2-40mA version can have a long connection cable.
The sensors are surface mounted or wall mounted over a provided adjustable base, giving the ability for leveling and orientation.

Seismic accelerometers can be used for early warning systems implementation. The concept is to install high precision accelerometers near seismic zones, generally located at the borders of two tectonic plates.

The interval of time between an earthquake and a local alert can be very small, from one minute to a few seconds. The waves travel through the ground at 1 to 5 kilometers each second, whereas the signals emitted by the sensors reach the urban areas almost instantly. This allows the population to execute the security processes in time, as long as they are not into the blind zone.

Contact GEObit experts to help you on designing your early-warning application.

The GEOtinyAC! compact digital accelerograph

GEOtinyAcc is a compact miniature digital accelerograph which integrates three acceleration channels. Actually is a GEOtiny! seismometer equipped with acceleration sensor. It supports high resolution 24bit digitizer (optional 32bit ADC), embedded linux OS and GPS or NTP timing. Seedlink server ensures reliable real time data telemetry while large storage volume ensures long period local data recording. The instrument has very low power consumption so it can operate getting powered from a small 12Vdc battery.

Design simplicity is the great advantage and it is reflected to the price which is only a fraction of the price of common commercial accelerographs. The sensor delivers superior signal-to-noise ratio and broadband response. The accelerograph communicates through ethernet CAT5 connection or wifi. The user has just to plug the power on and connect with the unit. The devise is compliant with the Los Angeles building code.

  • 3-axis accelerometers
  • Ultra Low Power Consumption
  • Olny 130mm D/ 76mm H
  • MEMS (Force balance / ASIC technology)
  • DC – 750Hz, Wide Dynamic Range 102 dB or 116 dB
  • Output range +/-2g to +/-12g linear
  • Noise level 6 ugrms/sqrt(Hz) or 0.3 ugrms/sqrt(Hz)
  • Integrated 24bit digitizer, miniseed data format
  • Local storage, and/or telemetry
  • Integrated seedlink and earthworm servers
  • Web interface, SSH, FTP, SFTP
  • Operating temperature -20 to +70oC
  • Aluminium IP68 case

This device is compliant with the Los Angeles building code.