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Customise Sensor
If you are connecting a sensor that is not in the predefined list, start from a similar type of
sensor and customise the parameters to match your sensor so that the data is stored with
the basic corrections that can be applied automatically when viewed in Waves.
If a setting has a colon, press the Right button to toggle its value, otherwise Right will
enter a menu to select a setting from a list. In the latter case, edit the parameter using the
Up and Down buttons, and use the Menu/Left button to save and exit.
The Sensor Name is a text field to help you identify the
model of sensor. This can be up to 20 characters long.
The Type of sensor you are using can be toggled between
Velocity (where units are defined in metres per second),
Acceleration (g), Pressure (pascal), Rotation (radians per
second), Displacement (metres), Volts, and Other.
Sensitivity can be set per channel, which indicates how
many Volts-per-unit your sensor outputs, e.g. 750V/m/s for
a Nanometrics Trillium Compact velocity sensor. Note that
Acceleration units will be saved as V/m/s
2
in accordance with
international standards, but entered as V/g for convenience
as most sensors are specified in this manner.
The Gecko can automatically correct for any zero-offset in
your sensor. If you do not wish to adjust the zero level, toggle the value to NONE. If your
sensor slowly drifts due to thermal variations, setting Zero-Correct to SLOW will correct
the signal offset at a rate of 1% of full scale per week. If you are only interested in high
frequency data (>1Hz) you can set it to FAST to correct at a rate of about 1% in 3 hours.
Some sensors have a calibration circuit whereby the recorder can send a voltage to the
sensor, and the components will respond accordingly to show that they are working as
expected. Some sensors require a control signal to tell it to enter calibration mode – the
type of control signal is set under the Cal Enable menu.
The Cal Type defines the type and amplitude of the signal size that is sent to the sensor.
There are four sizes of step voltages and sine waves: small, medium, large and extra large,
which generate amplitudes of about 0.5V, 1V, 5V, 10V respectively.
The Cal Duration is the number of seconds that the sine or step signal is active, which is
normally set to the long period response time of your broad band seismometer, or just a
few seconds for a short period seismometer or accelerometer. A “Step” calibrate will run for
twice the entered value to capture the trailing edge of the step response.
The frequency of the sine wave can also be set in the Cal Sine Freq menu, with available
choices being 1Hz, 5Hz, 10Hz, 50Hz, 100Hz, 500Hz, and 1000Hz.
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