Guralp CMG-DM24-Mk3-Variable

Below is some configuration-specific information to help you locate your instrument response.

Tap Table Lookup

The DM24 Mk3 Variable Gain datalogger generates sample rates for each channel by cascading decimation filters to create successive "taps" or sample rates. Some or all of these sample rates may be output. The FIR filters used for a given sample rate is determined by the tap sequence programmed into the datalogger at startup time. Each unique combination of taps is referenced by a "Tap Table Lookup" (TTL) number. Knowing this number is necessary to locate the correct instrument response, since a single sample rate can be generated in a variety of ways. The TTL can be found in one of these ways:

1. running Guralp's EAMs program

   • selecting "GDI channels display from the tools menu
   • choosing the data stream of interest and
   • clicking "View details".
   • The "Metadata" table in the resulting display lists the "gcf-tap-table-lookup".

2. retrieving the TTL byte by web interface (instructions here)

3. reading the Decimation Index (TTL) from the Scream "ViewInfo" window (instructions here)