Guralp Systems CMG-DM24 User Manual

Page 90

CMG-DM24

64MB Flash File buffer : 65,520 Blocks Written 65,520 Unread

16 Free

Here, a 64 Mb Flash memory store contains 65,520 data blocks, of
which none have already been downloaded. This leaves 16 blocks of

free space, since each block is exactly 1Kb long, and
(65,520 + 16) × 1 Kb = 65,536 Kb = 64 Mb.

Latest data [392] PLPGG SBHYX2 2006 1 18 14:55:57

Oldest data [400] PLPGG SBHYN4 2005 11 30 06:47:38

These two lines show the date and time of the oldest and newest data
in the buffer, together with the System ID (PLPGG) and the Stream IDs

(SBHYX2 and SBHYN4) of the corresponding data stream.

Triggered events

# 15 Filed @ 64,167 PLPGG SBHYZG 2006 1 5 10:31:30 Last

Event

This line gives the date and time of the last trigger, together with its
System ID and Stream ID as above. Also given is the event sequence

number (15, here) as used by the EVENTSLIST command, and the
position in the buffer where data from the event begins.

If a trigger has occurred, but no data was output (e.g. because the

digitizer was in DIRECT transmission mode), the digitizer will report

# 22 2006 1 18 14:48:36 No File Last Event

GPS
The next line describes the current status of the GPS system. When the
digitizer is first powered up, the message will be something like

2005 8 10 12:35:00 GPS control OFF Auto 3-D [-5 Not sync'd]

The message GPS control OFF denotes that the clock is not yet being
controlled by the GPS. Owing to noise purposely injected into the GPS

timing stream, as well as issues of signal travel time, the GPS time
cannot be directly used to synchronize the clock. Instead, the digitizer

maintains a rolling average of time measurements, and uses this to
apply corrections to the clock so that it remains accurate over a long

period.

The Auto 3-D message denotes that the signal is strong enough to
obtain a full 3-dimensional GPS fix. If the signal is weak, or there are

too few satellites visible to the receiver, you may see Auto 2-D here.
If the signal is too weak to obtain a fix, No FIX will be displayed.

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