Gecko Compact Operational manual

Gecko
141 Palmer Street, Richmond VIC 3121 Australia T:[phone] [email protected]
For all models: Compact, Rugged, Blast, Tremor, Prism, SMA & SMA-HR
Seismographs, Accelerographs
Recorders, Vibration Monitors

Gecko Firmware V6.2
Welcome to the world of simplified seismic recording with your new Kelunji Gecko
seismograph. Within minutes you can be recording earthquakes, blasts and other ground
vibrations using our latest generation instrument that makes high dynamic range, high
sample rate, low power, continuous recording accessible to experts and novices alike.
In the Gecko, we have simplified the modern digital seismograph. The low cost of flash
memory means you can save weeks, months, even years of continuous data on a single
memory card. The Gecko can record everything continuously while logging trigger times for
you to sort through back at the lab. Even if your trigger settings missed the event, you’ll
always be able to retrieve that chunk of time from the continuous archive.
An even more efficient way of managing your data is not to have to collect it at all, so we
have included a simple telemetry protocol that streams data packets over the Internet via a
cellular data modem or Ethernet/WiFi link. Data from all of your stations is then available in
a single archive for you to access whenever you need it. Simply install our free “Streams”
data reception software on your Windows, Mac or Linux PC and watch your data live on
screen while it is archived away to your PC. Streams is ideal for collating data from multiple
network-connected structural monitoring instruments. Download it free today from the SRC
website: https://www.src.com.au/downloads/live-stream/
Our “Waves” waveform analysis application is available as a free download for Windows,
Mac and Linux from http://www.src.com.au/downloads/waves/ . Each Gecko purchased is
entitled to one Waves product key that will remove the advertisement that pops up for 10
seconds when you launch the program. You can email [email protected] with your recorder
serial number to obtain a product key. Each product key can only be used once and is not
transferable to another computer.
Happy recording!
From the Gecko development team.

Table of Contents
Getting Started ................................................................................ 1
Setting up your recorder .................................................................................... 1
The User Interface ............................................................................................. 2
Menu Map ........................................................................................................... 3
The Home Screen ............................................................................. 4
Status Screen Loop – Right Button ..................................................................... 4
Realtime Data Loop – Up Button......................................................................... 5
Vector Sum .......................................................................................................5
Sensor Signal ....................................................................................................5
Raw Signal ........................................................................................................5
The Main Menu ................................................................................. 6
Unmount SD card ............................................................................................... 6
Data Storage .....................................................................................................7
Station Info ........................................................................................................ 7
Station Code......................................................................................................8
Network Code ....................................................................................................8
Location ID........................................................................................................8
Sample Rate ....................................................................................................... 9
Channels to Store ............................................................................................. 10
Channels to Send.............................................................................................. 10
Sensor Setup .................................................................................................... 11
3D Sensor ....................................................................................................... 11
1D Sensor ....................................................................................................... 14
Input Amplifier................................................................................................. 14
Trigger & Alarm................................................................................................ 15
Trigger List...................................................................................................... 15
Level Triggering ............................................................................................... 16
STA/LTA Triggering........................................................................................... 16
Alarm Outputs ................................................................................................. 17
System Alerts .................................................................................................. 17
On-screen Alerts .............................................................................................. 18
Telemetry ......................................................................................................... 18
Mode .............................................................................................................. 19
Device ............................................................................................................ 19
Settings File ..................................................................................................... 20
Start Calibration ............................................................................................... 20
Data Storage and Formats.............................................................. 21
The Root Directory ........................................................................................... 22
The Data Folder ............................................................................................... 22
The Histogram Folder........................................................................................ 23
MiniSEED files................................................................................................... 23

Upgrading the Gecko firmware ......................................................................... 24
Ports & Wiring................................................................................ 24
Power connector .............................................................................................. 24
Alarm & Communications port .......................................................................... 25
4D Sensor port (2018 Compact & Rugged) ....................................................... 25
1D Sensor port (mid-2019 Blast & SMA)........................................................... 25
Technical Specifications ................................................................. 26
Register your Gecko ....................................................................... 29
Warranty........................................................................................ 30
Extended warranty ........................................................................................... 30
Appendix A..................................................................................... 31
Installing the Gecko Blast or SMA..................................................................... 31
Gains, range and clip levels ............................................................................... 32
Installing the Gecko Pro-bodied sensors .......................................................... 33
Calibrating a Gecko SMA-HR .............................................................................. 35
Checking Prism Operation.................................................................................. 36
Appendix B..................................................................................... 37
Internal Battery ............................................................................................... 37
Charge Regulator ............................................................................................. 38
LED Patterns (routine) ...................................................................................... 38
LED Patterns (exceptions) ................................................................................. 38
Appendix C..................................................................................... 39
USR-W610 Ethernet & WiFi Adaptor ................................................................. 39
Quick Configure ............................................................................................... 39
Troubleshooting ............................................................................................... 41
Appendix D..................................................................................... 42
NTC 221 4G Modem & Ethernet Router ............................................................. 42

1
Getting Started
All Gecko models have a 2-pin power port, 6-pin alarm/communications port, and a coaxial
GPS aerial connection. From mid 2019 Gecko Blast & SMA models also have a 4-pin port for
an external sensor channel. Gecko Compact & Rugged have a 19-pin sensor connection.
Setting up your recorder
The two-pin connector is the power input to the Gecko. The default Gecko operating voltage
range is 11.8 to 24 Volts DC (useful for 12V DC battery over-discharge protection), but it
can be factory switched to extend the range to 7V to 30V DC at no cost. If the power is
removed then restored, the Gecko will restart using the saved settings.
The Gecko only takes a few seconds to initialise the operating system after power is applied.
If an SD card is installed at power-up, the card is checked during the boot process. When
the card is ready, the Gecko will start storing continuous data within a few seconds.
The small gold coaxial socket is the connection for the GPS aerial. The GPS is crucial in
maintaining accurate absolute time to synchronise recordings from various instruments and
monitoring locations, but it also provides global position information. Simply screw the GPS
cable plug onto the threaded GPS socket until finger-tight.
The Gecko Compact and Rugged is supplied with a sensor plug which you can attach to your
sensor cable. You can find the wiring diagram at the end of this manual. Align the keyed
plug with the socket and push it on, locking it in place with the bayonet-style collar.
At this point you now have a fully functioning recorder, but you will need to modify some
settings to suit your application. Setting a unique station code is an essential starting point.

2
The User Interface
The Gecko does not require a computer to control it. All recorder settings are accessible
through the LCD and are modified using the four control buttons.
Gecko Compact (above)
Gecko Rugged; and Gecko digital velocity sensors (above)
Gecko digital acceleration sensors (above)
SEISMOGRAPH
RIGHT
MENU
(LEFT)
UP DOWN
ACCELEROGRAPH
RIGHT
MENU
(LEFT)
UP DOWN

3
Menu Map
After start-up, pressing the Menu button will toggle between the main menu and the home
screen. The LCD backlight will stay on for 2 minutes from the last button press.
On most screens you can scroll Up and Down through a list and enter a menu item or
toggle a setting by using the Right button. Pressing the Menu button will save the current
setting and take you back one menu level.
Pressing Up from the home screen shows signal levels in various ways. Pressing the Right
and Down buttons modifies the signal levels, as described in the orange box below.
Depending on the model of Gecko and your current configuration, some menu items may be
hidden from view.
For example, if you have a Gecko with an internal 3D sensor, the 3D sensor menu will not
be accessible as users should not change the sensor configuration. Older model 3-channel
Gecko recorders will not show the 1D sensor menu, and if your chosen sensor does not
have a calibration duration, the Start Calibration option is hidden.
Peak Signal Sensor Signal Raw Values
3D 0.1234567 mm/s Next screen (shown at right) 2019-04-01 11:52:18 Next screen (shown at right) E: -2,726 0.6
max 11.1234567 mm/s uu Clear max values E: -0.0439408 mm/s uu Offset Signal to Zero N: 4,326 0.8
1D 80.2123546 dB N: 0.0360011 mm/s uq Clear Zero Offset Z: -698 0.7
max 101.1234567 dB
Back to Home Screen Z: -0.0011021 mm/s Back to Home Screen O: 12,356 1.2
p
Home Screen Info & Telemetry 3D/1D Sensor Info GPS location information Recent Triggers
2019-04-01 11:52:16 Volt: 14.06 250sps 3D Sensor Name & S/N Lat: -37.8189800 Time mm/s dB
GECKO Storing ENZO+ uTemp: 35.5° x1 uGecko Pro SMA-HR Long: 145.0109620 u0122:56s 690.1 105.0
GPS:04 Sending ___O+ #2000374 v6.2.4573 E:0123 N:4567 Z:8910 Sats: 12 Alt: 22m 2359:59s 10.3 89.1
32GB free:92.23495% Connected to Server Type: Acceleration hAcc: 6m vAcc: 14m 1326:46s 20.9 95.2
Station Information Save Continuous Data
Main Menu
Station Code Channel E: On
Send Continuous Data 3D Sensor
Unmount SD card > Network Code Channel N: On Channel E: Off Sensor Name
> Station Info Location ID (3D) Channel Z: On Channel N: Off > Type: Velocity
Sample Rate Location ID (1D) Channel O: On Channel Z: On Sensitivity ch E
Channels to Store 3D Vector: Off Channel O: Off Sensitivity ch N
Channels to Send 3D Vector: Off Sensitivity ch Z
3D Sensor
3D Sensor
Zero Correct: NONE
1D Sensor
1D Sensor
Select a Sensor
Select a Sensor
Cal Enable
Input Amplifier Select a Sensor > Sensor Serial No Customise Sensor Cal Type
Trigger & Alarm > Sensor Serial No Mass Lock > Geophone 28.8V/m/s Cal Duration
Telemetry Mass Unlock Geospace GS-1 1Hz Cal Sine Freq
Settings File Mass Centre ...<more> SIG+ Mode: Normal
Start Calibration
Trigger & Alarm
SIG- Mode: Normal
Level - High
Level Triggering
DC Offset: Normal
Communications
> Level - Low
STA/LTA Triggering
Enable: Off
STA/LTA Enable: Off > Sensor: 3D
% of Full Scale
> Mode: Continuous Alarm Outputs > Threshold Set Trigger Level 5.00
Device: Serial System Alerts STA window 1.2933 mm/s
...<more>
t
p
u
p
t

4
The Home Screen
The four lines on the home screen show:
• the Gecko clock’s date and time (in UTC – Universal Time Coordinated)
• the station code, and which channels are being stored to the SD card
• the number of GPS satellites visible; and what is being sent via Telemetry
• the SD card capacity and percentage of storage remaining
2020-09-01 06:17:52
GECKO Storing ENZO+
GPS:04 Sending ___O+
32GB free:92.23495%
“O” is the 4th channel on some Gecko models, and “+” is the vector sum of channels ENZ.
The “Storing” word animates using qdown arrows to indicate packets of data are being
written to the SD card. The “Sending” word animates using pup arrows to indicate packets
of data are being streamed to a remote computer.
Status Screen Loop – Right Button
The Gecko has several status pages accessible from the Home screen. Press the Right
button to scroll through them, or press the Menu button to return to the Home screen.
• The first screen shows input power voltage and CPU temperature, the current sample
rate and input amplifier (gain) setting, followed by the Gecko serial number and
firmware version number. The bottom line shows the telemetry connection status
• The next screen shows the name and serial number of the 3D sensor connected to
channels ENZ. The sensor type is shown on the bottom line
• If you have a 4-channel recorder, the next screen shows the 1D sensor information
• The next shows the GPS location information. The “hAcc” value is the horizontal
accuracy value of the GPS aerial position in metres as read from the GPS receiver,
and “vAcc” is the vertical accuracy.
• The final screen shows a list of the last 20 trigger times and peak values in the 10
seconds after the trigger time. An “s” after the time indicates it was an STA/LTA
trigger, a pindicates a Level-High trigger, and a qindicates a Level-Low trigger.
Use the Down button to scroll to older triggers, or Up to view the latest trigger.
Home Screen Info & Telemetry 3D/1D Sensor Info GPS location information Recent Triggers
2019-04-01 11:52:16 Volt: 14.06 250sps 3D Sensor Name & S/N Lat: -37.8189800 Time mm/s dB
GECKO Storing ENZO+ uTemp: 35.5° x1 uGecko Pro SMA-HR Long: 145.0109620 u0122:56s 690.1 105.0
GPS:04 Sending ___O+ #2000374 v6.2.4573 E:0123 N:4567 Z:8910 Sats: 12 Alt: 22m 2359:59s 10.3 89.1
32GB free:92.23495% Connected to Server Type: Acceleration hAcc: 6m vAcc: 14m 1326:46s 20.9 95.2
u

5
Realtime Data Loop – Up Button
Press the Up button from the Home screen to view real time sensor data.
Vector Sum
The first screen shows real time peak sensor output in
sensor units, calculated based on the sensor and gain
settings. Tap the sensor to see the numbers change.
It shows the live peak vector
sum of the 3D sensor, and holds the peak value (max). For
4-channel models, the live data from channel O is shown and
its peak (max) value is also held.
If you have a 3-channel recorder with an accelerometer connected (or have a Gecko SMA
variant) this screen will display an estimate of the Modified Mercalli Intensity (MMI) and
Philippine Earthquake Intensity Scale (PEIS) value based on the maximum displayed
acceleration. Press the Right button twice to clear the retained peak (max) values.
Sensor Signal
Press the Up button again to see the ground motion values
for each sensor axis. Pressing the Right button on this
screen will prompt you to either press the Right button
again to remove any signal offset (it averages the signal for
2 seconds), or press the Down button to clear the any existing offset correction. The Drift
Correction feature (see: 3D Sensor settings) will also correct signal offset over time.
Raw Signal
Pressing Up again will display the raw numbers from the analogue-to-digital converter
(ADC) in real time. The values shown are up to ±8.4 million recorder counts, which
represents a signed 24-bit range number.
The zero level can be controlled in the same way as the
Sensor Signal screen. If you have a 4-channel Gecko, the
date and time line will not be shown, with channel O
appearing at the bottom.
If STA/TA triggering is enabled, the STA/LTA ratio is also displayed in real time at the end of
each line. It is the ratio of the average signal in the short term divided by the average
signal in the long term. When nothing much is happening, this value will sit around 1.0, but
a short burst of anomalous signal will increase the number. This ratio may assist you in
determining at what level to set your STA/LTA trigger threshold.
3D 0.1234567 mm/s
max 11.1234567 mm/s
1D 80.0360011 dB
max 101.0011021 dB
Vector Sum Display
3D 0.002464 g
max 0.020267 g
MMI: IV PEIS: 4
2019-04-01 11:52:18
E: -0.0439408 mm/s
N: 0.0360011 mm/s
Z: -0.0011021 mm/s
2019-04-01 11:52:20
E: -2,726 0.6
N: 4,326 0.8
Z: -356 1.2

6
The Main Menu
Pressing the Menu button from the home screen will show you a list of actions and settings
for managing your recorder. The main menu includes some or all of the following items:
Main Menu
Unmount SD card
> Station Info
Sample Rate
Channels to Store
Channels to Send
3D sensor
1D sensor
Input Amplifier
Trigger & Alarm
Telemetry
Settings File
Start Calibration
If you change any settings, they are usually applied once you exit to the home screen. The
settings are automatically saved to the recorder’s configuration file.
Unmount SD card
Data is being sampled at all times, whether an SD card is present or not, because data may
be telemetered without an SD card. If there is no SD card, backfilling of unsent data will not
be possible.
Before you remove the SD card, you should unmount the SD card so that the system does
not try to write data to the card while it is being removed, an action that can corrupt the
current file, the FAT file system, or the SD card.
When you insert an SD card, it will automatically be mounted.

7
Data Storage
The Gecko is supplied with a 32GB SD card, formatted with the FAT file system. Larger
capacity SD cards can be used in the Gecko if they are pre-formatted as FAT (not exFAT).
To remove the card from a Gecko Compact 3ch (above, left) slide open the SD card cover
and press in the SD card to eject it. The SD card faces up, and it cannot be inserted upside-
down. For the Gecko Compact 4ch (above, centre), the SD card cover requires a quarter
turn anti-clockwise before removal. The SD card faces the rear of the recorder.
If you have a Rugged model with optional internal sensor, unscrew the card cover to access
the SD card slot (above, right). The SD card faces the rear of the recorder.
Insert the SD card into your computer (directly if you have an SD card slot, or via a USB
card reader) and you’ll be able to browse your continuous data files.
To re-insert the card, check you have the correct orientation and do not force the
card if it does not insert easily. Push the SD card down into the socket, ensuring you
feel the card spring back from push-lock. The SD card will automatically mount and
recording should resume. Check that the qarrows are animating over the word “Storing”
on the Home screen, which indicates data packets are being written “down” to the SD card.
Station Info
Every seismic monitoring point needs to have a unique identifier. As part of the MiniSEED
data format standard there are three tiers of identifier – Network, Station, and Location.
Station Information
Station Code
> Network Code
Location ID (3D)
Location ID (1D)

8
Station Code
Important! Please change your station code to a unique code, otherwise data
from all of your stations will be called GECKO and it will be difficult for
you to work out which data files came from which station!
This station code (default is GECKO) can be up to 5 characters long and can only contain
uppercase letters and numbers. If you wish to use less than 5 characters, end the code with
blank space character. Note that any characters after a blank space will be ignored (e.g. if
you enter “ABC 1” the Gecko will truncate the station code to “ABC”).
Enter Station Code
GECKO
A flashing block indicates the cursor position. Use the Up and Down buttons to scroll
through letters and numbers, and use the Right button to move to the next character.
Press the Left/Menu button when on the first character to save and exit.
Network Code
The MiniSEED format allows you to include a two character network code, which can be your
FDSN code. For example, the Seismology Research Centre uses “OZ”, Geoscience Australia
uses “AU”, and the British Geological Survey uses “GB”. You can register for an FDSN code
at fdsn.org, or you can use this field for you own identification purposes.
Location ID
A seismic monitoring location may have multiple monitoring points, so rather than coming
up with a station code for each, they can all use the same station code with a unique
Location ID. This field is any two character code. For example, if you are monitoring the
basement, middle and top of a building you could use Location IDs of B1, M1, and T1; or
simply 01, 02 and 03.
Alternatively you could use the Location ID to group Geckos with different Station Codes to
a common location (e.g. several strong motion accelerographs on different floors in the
same building), allowing them to be grouped in the Streams intensity display web page.
The default value for channels ENZ is 00, and for 4-channel systems channel O has ID 01.

9
Sample Rate
The Gecko uses filtering and decimation to produce the
following sample rates: 50, 100, 200, 400, and 800 sps.
The standard ADC sample rates of 250, 500, 1000, 2000
and 4000 sps do not use additional filtering.
Scroll to the sample rate you wish to use, then press the
Menu button to exit and apply the new sample rate.
Channel Naming
The naming of channels has been automated in the Gecko based on the selected sample
rate and sensor type, with preset channel names.
The SEED standard states that each channel requires a 3-letter code, where the first letter
indicates the Band Code, the second letter indicates the Instrument Code, and the third
letter is the Orientation Code. Detailed information on this standard can be found here:
https://ds.iris.edu/ds/nodes/dmc/data/formats/seed-channel-naming/
The Gecko will set the first letter of the channel name based on the sample rate:
• B: 50 sps
• H: 100 & 200 sps
• C: 250, 400, 500, 800 sps
• F: 1000, 2000, 4000 sps
The Gecko will set the second letter of the channel name based on the sensor type:
• H: Velocity Seismometer
• N: Accelerometer
• D: Pressure Sensor (e.g. Microphone)
• J: Rotation Sensor
• Y: Displacement Sensor
• Q: Voltage
The Gecko will set the third letter of the channel name based on the channel number:
• E: channel 1, typically used for East, Transverse, or X
• N: channel 2, typically used for North, Radial, or Y
• Z: channel 3, typically used for Up, Vertical, or Z
• O: channel 4, typically used for Outdoor Microphone or an extra Vertical sensor
For example, the vertical channel of a 50sps broadband seismograph would be BHZ, where
a horizontal channel of a 100sps structural monitoring accelerograph might be HNE or HNN.
The data stored as the vector sum of the 3D sensor uses channel code SUM and will use the
same location ID as channels E, N, and Z to reinforce the association with those channels.
Select Sample Rate
50 sps
> 100 sps
200 sps
250 sps
...<more>

10
Channels to Store
You can turn off any unused channels to save storage space. Storing the vector sum is a
waste of space if you are already storing ENZ. Toggle the channels on or off as required.
Save Continuous Data
Channel E: On
> Channel N: On
Channel Z: On
Channel O: On
3D Vector: Off
The 3D Vector channel should not be enabled unless it is required for data if telemetry
bandwidth is limited. Note that if a channel is enabled for telemetry (see next setting
below), it will automatically be stored to the SD card to ensure the data is available for
backfill should the communication link drop out.
If all channels are accidentally turned off, the Z channel is automatically re-enabled to
ensure at least one channel is being recorded. Note that if a channel is turned off here, it
will also be turned off in the “Channels to Send” settings – see below.
Channels to Send
You can select which channels to send continuously to your remote server. For blast and
structural vibration monitoring applications you may choose to send the 3D Vector sum
channel continuously, storing the ENZO channels to be streamed only when a trigger
process detects an event.
Send Continuous Data
Channel E: Off
> Channel N: Off
Channel Z: On
Channel O: Off
3D Vector: Off
Toggle the channels that you want to send continuously on or off using the Right button.
Note that if a channel is enabled for telemetry, it will automatically be turned on in the
“Channels to Store” settings as the stored data is required for backfilling gaps in data
telemetry. Disabling a channel in telemetry will not disable that channel in the “Channels to
Store” settings.

11
Sensor Setup
This section of the user manual applies to Gecko Compact, Rugged, Blast and SMA models only. For all
other models, skip ahead to the Input Amplifier section.
3D Sensor
> Select a Sensor
Sensor Serial No.
Mass Lock
Mass Unlock
Mass Centre
3D Sensor
This menu has items that deal with 3D sensor information and control. This will not be
visible in the Blast or SMA, but the same method applies for setting up the 1D sensor, so
Blast & SMA users should read this section.
Select a Sensor
The Gecko has a range of popular sensors settings preloaded into the menu to save users
the trouble of entering all of the parameters that allow the data to be displayed in
engineering units (e.g. mm/s, g, mm, dB, rad/s, etc.) rather than recorder counts.
Select a Sensor
Customise Sensor
> 28.8V/m/s Geophone
Geospace HS-1 2Hz
Guralp 3T
Trillium Compact
<more>
Scroll down to the sensor you have connected and press the Menu/Left button to exit and
save. This will fill the standard sensor information to the 3D sensor, and you can then
modify the settings for your particular sensor. To do this, re-enter the “Select a Sensor”
menu and press the Right button on Customise Sensor to edit the parameters.

12
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/s2in 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.
3D Sensor
Sensor Name
> Type: Velocity
Sensitivity E
Sensitivity N
Sensitivity Z
Zero-Correct: SLOW
Cal Enable
Cal Type
Cal Duration
Cal Sine Freq
SIG+ Mode: Normal
SIG- Mode: Normal
DC Offset: Normal

13
Previously known as “Input Mode” the SIG+ Mode setting tells the Gecko whether or not
power needs to be applied to the sensor channel positive wires (pins C, E, G and S on the
Gecko sensor connector). For most sensors, this mode should be set to “Normal”, but if you
are using an IEPE sensor, you can select “25V” which will put a 25V of DC power at 4mA out
to the sensor channel.
WARNING!Enabling SIG+ 25V output to non-IEPE sensors may damage your sensor
Previously known as “Sensor Wiring” the SIG- Mode tells the Gecko whether the sensor
channel negative wires (pins D, F, H & T on the sensor connector) need to be connected to
power ground or not. Most sensors require you to measure the difference between the
positive and negative wires, so the “Normal” setting would be used in most cases. If your
sensor requires the negative channel wire to be connected to power ground (e.g. for IEPE
sensors) then select “Ground”.
The DC Offset filter when enabled electrically removes signal offset by introducing a low
order high pass (~1.6Hz) frequency filter. For most sensors, it is best to leave this setting
as “Normal”. Do not enable this filter for long-period or broadband seismometers.
Some sensors (e.g. IEPE accelerometers) only output positive voltages, often over a 0-5V
range. At rest the signal will often sit at mid point of this range (known as “Bias voltage” but it
can be anywhere from about +2.5V to +12V DC. As the sensor moves, the voltage output
moves up or down from this DC offset by up half of the sensor’s range. The Gecko can remove
a number of counts from the signal after digitisation, but half of the -20V to +20V input range
of the Gecko is wasted. By enabling the DC Offset Filter, the pre-digitised signal is brought
down to almost 0V, and the digitised signal then moves between negative and positive
voltages around the zero level. This allows you to use a higher Input Amplifier setting (for
example of x8 to stretch a ±2.5V range to the Gecko’s full ±20V) to utilise the full dynamic
range of the Gecko’s 24-bit resolution.
Sensor Serial No.
A 20-character field is available to record your sensor’s serial number. This information is
stored in the station status text file for future reference. Upper and lower case letters,
numbers, and some special characters are available.
Mass Lock, Unlock, & Centre
Guralp 3-series seismometers have motorised mass controllers that allow the delicate
sensor components to be locked in place for transport and unlocked after installation. See
the sensor manual for more information. Activating Lock , Unlock and Centre controls
simply connects the corresponding pin on the sensor connector to Ground for 5 seconds, so
the feature could be used for other purposes if required.

14
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-
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.
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.
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.
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.
1D Sensor
Sensor Name
> Type: Pressure
Sensitivity
Input Range
x1
> x2
x4
x8
x16
x32
x64
<more, most models>

15
Trigger & Alarm
The primary function of the Gecko is to record data continuously, but triggering is still
required to help detect events of interest and to control alarms. The Gecko has two Level
trigger processes and an STA/LTA trigger process that can be enabled and disabled. The
Gecko also monitors some system parameters that can generate an alarm.
Trigger & Alarm
Level – High
> Level – Low
STA/LTA
Alarm Outputs
System Alerts
The Gecko logs the trigger time to a text file that can be used to help you find the data in
the continuous archive. This “trig.txt” file is located in the top level folder of the SD card.
We have developed a Windows application that can be copied to the Gecko SD card and run
from a PC that will scan the trig.txt folder and then automatically extract the continuous
data from the archive. The program will create a discreet file for each trigger time, stored in
a folder called “reports” on the SD card. Each waveform file contains one minute of data
before and after the trigger time. At the same time a PDF report is generated for the
triggered event, with files named based on the local time in your PC. This app simplifies
vibration monitoring reporting for non-technical users.
Trigger List
The latest 20 trigger times stored in the “trig.txt” file are also visible via the LCD by
pressing the Right button from the home screen until you see the trigger list.
Time mm/s dB
0123:45s 697.1 155.1
2359:59s 25.6 88.8
2230:00s 11.1 70.0
The latest event is at the top of the list (time in UTC) and you can scroll down to view older
trigger times. The peak 3D and 1D signal levels that occurred within the first 10 seconds
after the event was detected are shown in the units of the 3D and 1D sensor.
An “s” after the trigger time indicates the Trigger was generated by the STA/LTA process.
Similarly “p” indicates a Level-High trigger, and “q” indicates a Level-Low trigger.

16
Level Triggering
By default each Level trigger process is OFF, but simply toggle this using the Right button.
The Gecko can trigger on the vector sum of the 3D sensor
channels, or from the 1D sensor channel. The percentage
level of the trigger threshold will affect the ground motion
units displayed on the Set Trigger Level screen. For
accelerometers, the estimated MMI and PEIS intensity that
relates to this trigger threshold will also be displayed.
Use the Up/Down buttons to change the number values
from 0.01% to 99.99% of the recorder’s full scale range. The
line below will update with the ground motion value based on
the calibrated sensor sensitivity and gain of your Gecko.
STA/LTA Triggering
By default the STA/LTA trigger process is OFF. Toggle this ON/OFF using the Right button.
The Short Term Average (STA) signal level divided by the
Long Term Average (LTA)
signal level produces a ratio
indicating how much above-
average signal is occurring.
If you want to declare and event when the short term
average signal level is three times higher than the long term
average signal level, you set the Threshold to 3. The length of the short and long term
time windows is also user selectable. The LTA value must be larger than the STA value.
Signal averages can be calculated using the raw data or filtered to suit to local earthquake
detection. On the Filtersline, use the Right button to toggle the 2-20Hz filter on or off.
The STA/LTA algorithm can run on one of the triaxial channels (Z, N or E), on the 1D
channel, or on all of the 3D input channels. Toggle the Channel using the Right button.
A more detailed explanation
of the STA/LTA trigger
algorithm is provided in our
Waves data analysis
application’s user manual.
You can visualise the effect
of changing the various
STA/LTA settings using
Waves.
Level Triggering
Enable: On
> Sensor: 3D
Set Trigger Level
% of Full Scale
5.00 %
0.10316 g
MMI: VI PEIS: 6
STA/LTA Triggering
Enable: Off
> Threshold
STA window
LTA window
Filters: 2-20Hz
Channel: 3D
Short Term Average
2.0 seconds
averaging window