Guralp Systems CMG-1T - Manual (Page 29)

Operator’s Guide CMG-1T Ocean Bottom
Seismometer
September, 1999, Issue C Section 8,
Page 1
8. SEISMOMETER AND LEVELLING BOWL CONTROL
COMMANDS
The operation of the OBS system is carried out by a set of (English) command
words entered from a computer terminal connected to the system serial port.
The described commands control the operation of the OBS to lock the sensor
masses, unlock the sensor masses and centre the seismometers once the sensor
masses are unlocked.
Prior to unlocking the sensor masses the levelling bowl would be required to be
levelled after system installation. The bowl levelling commands are Datum,
level and, bowl-align.
All the commands consist of one or two words. With two word commands the
first word is the parameter (qualifier) for the second which is the actual
command to be executed.
SEISMOMETER COMMANDS
Three commands are available.
a)
LOCK - initiates locking sequence.
b) UNLOCK - initiates the unlocking sequence.
c) CENTRE - initiates the mass centring sequence.
Each of these commands is preceded by a qualifier specifying the instrument to
operate on.
Z
- specifies vertical, (Z) sensor
N/S - specifies north/south. horizontal sensor
E/W - specifies east/west horizontal sensor
ALL - all 3 sensors execute command.
Examples:
Z unlock - unlocks vertical sensor
ALL unlock - unlocks all the sensors
ALL centre - centres all the sensors.
BOWL LEVELLING COMMANDS
DATUM
- sets bowl tilt and rotate positions to origin. The origin is
described as no tilt and rotate datum position parallel to X
axis.
LEVEL
- returns the bowl to DATUM, after which automatically
levels the bowl to within
±
0.3 degrees. The range of
levelling is
±
30 degrees.
BOWL-ALIGN - This command can be used to correct small deviations