# Earthworm Program:
wftimefilter Overview

(last revised 1 June 2006)
This new module was created to "sanitize" incoming waveform data streams to the liking of Earthworm modules. It reads waveform data (compressed or uncompressed) from one transport ring and writes it to another ring, filtering out duplicate data, time overlaps and bogus future timestamped data. Timestamp checks are done for each channel independently. The check for bogus future timestamps requires that the system clock is set to network time.
Wftimefilter can be configured to output the messages using the original installation/moduleid or its own installation/moduleid. However, it does not alter the contents of the message in any way.
Systems which are importing data using import_ack/export*ack should probably use wftimefilter to remove possible duplicate data after an import/export reconnect. Systems importing waveform data from non-Earthworm data sources should also consider running wftimefilter to ensure that only chronological timeseries enter their own Earthworm processing.
Modifed to allow additional optional behavior:

1. Rejecting packets that have a sample-rate different than the expected one for the channel.
2. Limiting per-channel logging, to limit logfile size and increase readability.
3. Adding per-channel daily summaries of errors and warnings.
4. Adding the ability to issue a STATUS message to a ring as a part of the daily summary.
5. Default behavior should be unchanged.

This module was written by Lynn Dietz for the CISN.

Module Index | wftimefilter Commands