Guralp Systems CMG-DCM build <10,000 - Manual (Page 99)

Operator's Guide
In standard mode, the only option available is to disable BRP
rewinding. In some modes, some digitisers will not allow BRP to
rewind to earlier blocks. In these modes, missed packets will, instead,
be sent at a later time. However, the log-file will accumulate many
entries about sending NAKs and giving up. These may be avoided by
telling the receiver that its digitiser is using one of these modes and
that rewinding will not work. The log messages are harmless, so leave
this check-box clear if unsure.
The following additional options appear in expert mode:
The Transmission delay text field allows the operator to specify the
total delay incurred during packet transmission from the attached
digitiser. Digitisers can produce special “RTSTATUS” packets which
can be used to synchronise the NTP subsystem and, hence, the system
clock, with the digitiser's own GPS-synchronised clock (see section 6.3
on page 64). Unlike normal NTP peer dialogues, there is no
transmission delay discovery mechanism so, for optimal accuracy, it is
important to specify the value here. The ordinary delay associated
with packet transmission down a “short” serial cable is already
calculated and used, so this field only needs populating if additional
delays generated by, say, line drivers or modems, are encountered.
It may sometimes be desirable, for debugging purposes, to separate log
messages for this input from the standard system log. The Log file text
field can be populated with a path name which will then be used for
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