Guralp Systems CMG-3ESPCD User Manual

Page 62

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CMG-3ESPCD Digital Broadband Seismometer

Command line interface

Tells the digitiser which kind of GPS is attached to it. The argument type
can be one of

0, if no GPS is available,

1, for attached Trimble GPS equipment,

2, for attached Garmin GPS equipment, or

3, if GPS information should be obtained from upstream units (stream

sync mode.)

6.2.4 BAUD

Syntax: port baud­rate BAUD

Sets the baud rate for one of the serial ports on the digitiser, in bytes per

second. The argument port is a small integer specifying the port: Most units
have port 0 assigned to data output and communication, port 1 to GPS input,

and port 2 to the DATA IN port. For example,

0 38400 BAUD

1 4800 BAUD
2 38400 BAUD

This will reset a standard single-sensor digitiser to its default configuration.
The allowable values for baud-rate are 4800, 7200, 9600, 14400, 19200, 38400,

57600 and 1152 (for 115200 baud). GPS inputs should remain set at 4800
baud.

6.2.5 AZIMUTH

Syntax: instrument angle AZIMUTH

Some borehole digitisers can rotate incoming signals algorithmically as they
are digitised. This feature allows you to compensate for an instrument being

out of alignment with the North/South axis. To use it, first measure the
orientation of the sensor, then connect to the digitiser and issue an AZIMUTH

command, giving the angle you have measured.

The argument instrument tells the digitiser which instrument to apply the

rotation to; 0 for a 4-channel digitiser.

The argument angle is the measured angle of deviation from the North/South

axis, in tenths of a degree. The angle of deviation is the negative of the angle
by which you want incoming signals to be rotated. Like all other parameters,

it must be an integer (i.e. a whole number of tenths of a degree).

You can measure the orientation of a borehole sensor by placing a reference

sensor nearby and carrying out coherence calculations. An extension to
Scream! is available which can do this for you. For details, see the manual for

Scream!, MAN-SWA-0001.

MAN-C3E-0002

62

Issue B - November 2013

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