Guralp Systems CMG-CD24 User Manual

Page 90

CMG-CD24

7.2.2 Using CD24 triggering to activate external equipment

If your equipment can trigger from the same voltage as the CD24's

power supply, the simplest arrangement is to use the voltage across the
sensor's power supply as the trigger supply.

•

Connect the ground pin (B) to your equipment's trigger return

line. If your equipment does not have a separate trigger return
line, consult its documentation for how to apply trigger voltages.

(The diagram above does not show the power supply to either
the sensor or the triggered equipment: only the triggering system

is shown).

Because a trigger signal may last for only a short time, using
pins T and B directly to power your external equipment is not

normally advisable. Ideally, the equipment should be
continuously powered and listening on dedicated trigger input

lines. If this is not possible, it may be enough to build a control
circuit with a time-out period, which supplies your equipment

with power for a suitable minimum length of time whenever a
trigger is activated.

The digitiser cannot anticipate a trigger. Pre-trigger recording is

achieved using a continuously-updated ring-buffer of the most

Issue C