Seismic Source DAQlink III - Multiple Daqlink Triggering - Trigger on Time Feature

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5.11 Multiple DAQlink III Triggering -– Trigger on Time feature
The DAQlink III has various options for triggering.
For Multiple DAQlink III triggering a special “Trigger on Time” feature is built in on all
modes. When one DAQlink III unit triggers a special “Trigger on Time” message is sent to all
other DAQlink III units through the Ethernet Network. This message is received by all of the
other DAQlink III units and they will trigger and send data back to the main computer.
The “Trigger on Time” feature requires a GPS receiver at every DAQlink III unit to
synchronize the internal clock in the DAQlink III. The DAQlink III unit must receive at least 10
valid PPS pulses from the GPS system to synchronize the internal clock. After the internal clock
has been synchronized, then GPS signal can be removed. This allows operation in areas where
the GPS coverage is intermittent. If the internal clock has not been synchronized, then the
“Trigger on Time” message is ignored.
After receipt of the “Trigger on Time” message, all of the DAQlink III units will retrieve
the appropriate data stored in the memory of the unit. The exact time of the trigger event is used
and the data from each DAQlink III is sent back to the central recording system.
This special “Trigger on Time” feature allows multiple DAQlink III units to be used with
only the Ethernet and GPS connected at each DAQlink III.
Very accurate triggering can be performed using Multiple DAQlink III units and Wireless
Ethernet systems.