Guralp Systems CD1.1 - Manual (Page 73)

Operator's Guide
11.2 Latency
When using sample rates of 200sps and below, the adaptive
block-based transfer mechanism used by Güralp CMG-DM24s or
CMG-CD24s can conflict with the fixed-duration frames used by
CD1.1.
This can be solved in one of two ways. Either the ADC can be
configured to emit blocks more frequently, or the latency of the
subframe generation can be increased (i.e. the CD1.1 converter
will wait for a longer period of time for more blocks to arrive).
To configure a CMG-DM24 or CMG-CD24 to emit blocks more
frequently, visit the relevant digitiser configuration page of the
CMG_EAM's web interface (a menu item appears automatically
for each connected digitiser under “Configuration” → “System
setup”). Scroll down to the “Compression mode” section and,
in the drop-down menu, select “off (8 bit 20 records max)”.
If you are using a fixed-block-size transfer protocol such as
Scream, this will consume significantly more bandwidth. If this
is unacceptable, increase the frame assembly time in the
CD1.1 converter.
If you alter neither the ADC configuration nor the CD1.1
converter's time-out, subframes which do not have all the
required samples will be deferred once the assembly time-out
is completed.
Note that the compression command does not affect mass
position channel data so, if these are being transmitted, they
will almost always be deferred.
June 2010 73