Data Services Newsletter

Volume 11 : No 4 : Winter 2009

The IRIS DMC Nominal Response Library

In 2006, the IRIS DMC began to collect an “authoritative” set of manufacturers’ recommended nominal instrument responses in SEED RESP format and publish these on the web at http://ds.iris.edu/NRL. The goal behind the Library is to make it easier for the seismological community to both share and create metadata for common instrumentation, and to improve response accuracy for users of the data. Because the wide range of features available in modern instrumentation can make locating the appropriate response a challenge, the Library organizes responses based on hardware and/or acquisition choices, elucidating these choices as needed. “Nominal” responses may also have limits to their validity, so the Library notes these as well. ( See, for example, http://ds.iris.edu/NRL/sensors/sercel/sercel_l22d_sensors.html)

At the time of this article, this growing Nominal Response Library (NRL) includes

  • 146 sensor responses (representing 10 sensor manufacturers) and
  • 4705 datalogger responses (from 7 datalogger manufacturers).

Responses in the NRL are generated directly from manufacturers’ documentation or other direct communication. Once constructed, these responses are checked to make sure tha

  • the response curves are reasonable,
  • attributes such as gain, fir delays and sample rate are correct and
  • the response file is a valid SEED RESP file.

The NRL is accessible in two forms:

  1. on the web at http://ds.iris.edu/NRL, and
  2. embedded in the latest release of the Portable Data Collection Center (PDCC) software (please see this supporting article for details.)

Within PDCC, a new “decision guide” called NRLTool asks users the appropriate series of questions needed to locate the right responses for their sensor and datalogger configuration based on options their specific instruments allow. It then combines the sensor and datalogger RESP files into a full response and returns it to PDCC for inclusion in a dataless SEED file. The NRLTool has the added benefit that, if the user has an active Internet connection, it will alert the user when the NRL has been updated at the DMC and offer to download and install the updated Library.

More information

by Mary Templeton and Rick Benson (IRIS Data Management Center)

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