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1D Sensor
If you have a 4-channel Gecko Compact, Rugged, Blast or SMA, you can set up your 1D
sensor in a similar way to the 3D sensor. Select a sensor from the list and optionally re-
1D Sensor
Sensor Name
> Type: Pressure
Sensitivity
Set the sensor serial number using the only other menu option in the 1D Sensor menu.
Input Amplifier
The Gecko is, fundamentally, a high speed, high resolution Voltage logger. It measures the
voltage across each channel's pair of wires, and it can measure from -20V to +20V DC at
24-bit resolution. This 40V peak-to-peak range is converted into a 24-bit number, producing
a value between 0 and 16,777,216 counts, which equates to 419,430 counts per volt.
Input Range
x1
>
x2
x4
x8
x16
x32
x64
<more, most models>
If you are using a passive sensor (e.g. geophone) you can use very higher gains to see
smaller signals at higher resolution. For example, the Gecko Tremor's geophones (nominal
sensitivity of 78.74 V/m/s) normally have a clip level of 254mm/s, but by using a gain of
x16 you can see smaller signals and get a similar effective sensitivity (1260 V/m/s) and clip
level (16mm/s) as a typical short period active seismometer.
The maximum gain for a 40Vpp sensor is x512, giving a measurement range of ±0.04 volts.
Most seismic sensors would be continually clipping at this range, the exception being low
sensitivity passive geophones.
The Gecko Pro SMA-HR and Prism sensors have a 60Vpp range, so these recorders have a
sensitivity of 279620 counts per volt, with a maximum gain of x64.
enter the menu to customise its name, units and sensitivity.
The SIG+, SIG-, DC Offset, & Zero-Correct settings of the
1D sensor are set as for the 3D sensor, and separate
calibration settings are not available for the 1D sensor.
If you are using a sensor with a 40Vpp output (for ±10V
differential output sensors, such as Nanometrics or Guralp
seismometers) set the gain to x1.
If you are using sensors with lower full scale voltage, use the
input amplifier to utilise the full dynamic range of the Gecko.
For example, if you have a ±4V MEMS accelerometers (as
used in the Gecko SMA) you should use a gain of x4 to
shrink the input range to ±5V to record the signal at higher
resolution. Note that DC offsets will also be amplified.
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