Technical Specifications

Block Diagram

_images/six3v2blockdiagram.png

Note that in Sixaola4, the MEMS sensors have been replaced by OSOP’s GeoFlex sensor

It is really very simple, don’t you think?!

The velocity sensors are 4.5 Hz geophones electronically extended to 0.5 Hz then digitized with an ADS1281 24 bit instrument-grade digitizer. The data flows into an ARM Cortex4 procesor where the data is time stamped. There are also three channels of MEMS acelerometer data.

Power input is 9 volts and that is highly protected and conditioned.

The GPS is a LINX module which needs to see five satellites to acquire Lock status. See Timing for more details.

The computer is a BeagleBone Black (BBB) which is connected to the STM32 and to a bluetooth reciever. The computer runs Debian Linux (see Operating system for more details). Attached to the BBB is a USB which serves as the storage when the Sixaola is configured in Trigger Logger or Data Logger Modes (see Data Flow Mode for more details).

A PIC runs a watchdog which monitores several processes and issues a reboot if needed.

Instrument Response

The Sixaola has a flat frequency response from 0.5 Hertz (2 seconds) to 80% Nyquist:

_images/RESP.based.on.circuit.100sps.combined.with.sensitivity.from.pavlis.decimation.included.png

Sixaola velocity channel instrument response

The instrument response of the velocity channels for Sixaola3 and Sixaola4 is the same.

For more details: Click here to download the technical specifications sheet for Sixaola4-V2.

For more details: Click here to download the technical specifications sheet for Sixaola3-V2.

Download the instrument response

You can download the complete instrument response in dataless and RESP formats directly from your Sixaola (station name, sample rates, latitude, longitude, elevation are automatically populated):

Open the web interface >> sign in >> navigate to Instrumentation >> Click the “Download instrument response” button.

Self-Noise

See also: ASL report

OSOP designed the Sixaola for local and regional earthquake detection.

Below we compare the self-noise for 3 co-located Sixaola short-period seismometers using the Sleeman method. The New High- and Low- Noise Models (NHNM, NLNM) from Peterson, 1993 and earthquake models for local and regional events from Clinton and Heaton, 2002 are plotted for comparison.

_images/sleeman-s75-s76-s77-self-noise-localEQ.png

Sixaola self-noise compared to local seismicity

_images/sleeman-s75-s76-s77-self-noise-regionalEQ.png

Sixaola self-noise compared to regional seismicity

References:

Clinton, J.F. and Heaton, T.H. (2002) Potential advantages of a strong-motion velocity meter over a strong-motion accelerometer, Seismological Research Letters 73: 338 pp.

Peterson, J. (1993) Observations and modeling of seismic background noise, USGS Open-File Report 93-322: 95 pp.

Sleeman, R., van Wettum, A., Trampert, J. (2006) Three-channel correlation analysis: A new technique to measure instrumental noise of digitizers and seismic sensors. Bulletin of the Seismological Society of America 96: 258-271.

Technical Specifications Sheet

Click here to download the technical specifications sheet for Sixaola4-V2.

Click here to download the technical specifications sheet for Sixaola3-V2.

See also:

Input Voltage Requirements

Warning

Pay special attention here if you are using a solar system and be sure to set your float properly so that the Sixaola does not reset

Sixaola4-V2

Voltage in Description
< 8.3v Power completely removed
8.3 to 8.5 Hysterisis zone Power removed when input voltage falls below 8.3v. Enter reset mode when input voltage increases above 8.5v.
8.5 to 9.7 Reset active.
9.7 to 10.8 Hysterisis zone. Reset gets taken away when input voltage increases above 10.8v. Reset gets applied again when input voltage falls below 9.7v.
9.7 to 16.5 Running.
15.5 to 16.5 Hysterisis zone. Reset applied when input voltage increases above 16.5v. Reset removed when input voltage decreases below 15.5v. Enter reset mode when power falls from above 17v to 16.1v.
16.5 to 17 Reset active.
17 to 220 Power completely removed.
_images/sixaola4V2

Sixaola4-V2: Input Voltage Behavior

Sixaola3-V2 (post-Sept, 2015)

Voltage in Description
< 9v Power completely removed
9 to 9.4 Hysterisis zone Reset applied when input voltage falls below 9.5v. Enter reset mode when input voltage increases above 9.4v.
9.4 to 9.9 Reset active.
9.4 to 10.7 Hysterisis zone Reset gets taken away when input voltage increases above 10.7v. Reset gets applied when input voltage falls below 9.9v.
9.9 to 15.1 Running.
14.6 to 15.1 Hysterisis zone. Reset applied when input voltage increases above 15.1v. Reset removed when input voltage decreases below 14.6v.
15.1 to 15.9 Hysterisis zone.
15.9 to 220 Power completely removed.
_images/sixaola3V2-postSept2015

Sixaola3-V2 (post-Sept, 2015): Input Voltage Behavior

Sixaola3-V2 (pre-Sept, 2015)

Voltage in Description
< 9v Power completely removed
9 to 9.4 Hysterisis zone. Reset applied when input voltage falls below 9.5v. Enter reset mode when input voltage increases above 9.4v.
9.4 to 10.7 Hysterisis zone (*). Reset gets taken away when input voltage increases above 10.7v. Reset gets applied when input voltage falls below 9.5v.
9.5 to 14.5 Running.
14.2 to 14.5 Hysterisis zone. Reset applied when input voltage increases above 14.5v. Reset removed when input voltage decreases below 14.2v.
14.5 to 15.1 Reset active.
15.1 to 15.8 Hysterisis zone.
15.8 to 220 Power completely removed.

(*) CAUTION: When increasing the voltage from 10.1 to 10.7 volts, the Sixaola could enter a state of a infinite reset loop if the power hovers in this range.

_images/sixaola3V2-preSept2015

Sixaola3-V2 (pre-Sept, 2015): Input Voltage Behavior