The IRIS DMS has been in the process of shifting data archiving from physical tapes to electronic transfer for a few years. Our first major effort to receive data electronically began with the installation of the Frame Relay Circuit between the US National Data Center for the CTBT at Patrick Air Force Base, Florida, and the IRIS DMC. Data from several Air Force stations and arrays have been sent to the IRIS DMC since May, 1998. Data from AFTAC are sent using CD-1 protocol and received using the Antelope software from Boulder Real Time Technologies. The data are received, converted to miniSEED format and archived automatically at the DMC. These data are available using the same suite of data request tools as other data at the DMC. Data from Patrick AFB are available using network code IM. Unfortunately at this time only stations on US soil are included in the data stream from Patrick AFB.
To reduce the problems associated with data delivery by tape from the Data Collection Centers to the IRIS DMC, the DMS installed Frame Relay Communication Circuits between the DMC in Seattle and the IRIS/USGS DCC in Albuquerque and the IRIS/IDA DCC in San Diego. At the present time, data from the two GSN DCCs are routinely transferred to the DMC using a system built around ftp. As with the data from Patrick Air Force Base, data that arrive at the DMC from the DCCs are automatically archived without intervention by the operator. We have found that the reliability of the electronic transfer of GSN data has improved the reliability of data delivery as well as allowing the number of technicians at the DMC and the DCCs to actually decrease through attrition.
The IRIS DMC is involved in a fairly ambitious effort to significantly increase the amount of data that the DMC receives in real time or near-real time. There are two primary systems that have been developed recently (see companion article) that the DMC intends to exploit to receive data in near-real time. The Antelope System from BRTT was initially installed to receive data from the Air Force seismic stations. Concurrently the USGS has developed the Earthworm system. Both systems are capable of real time transmission of data. The DMC is either presently receiving or shortly will be receiving data from the following networks from these two systems:
|Data Source||Network Code||Number of Stations||Real Time System|
|Patrick Air Force Base||IM||50||Antelope|
|IRIS/USGS GSN via LISS||IU, IC||37||Antelope|
|IRIS/IDA GSN via NRTS||II||13||Antelope|
|PASSCAL BB Array||XF-2000||73||Antelope|
|US National Network||US,LB||45||Earthworm|
|University of Washington||UW||266||Earthworm|
|University of Utah||UU||124||Earthworm|
|New England Nets (MIT)||NE||*||Earthworm|
|Memphis University Nets||ET||*||Earthworm|
|Delaware Geological Survey||DG||*||Earthworm|
* – Data not yet flowing
At the present time the staff at the DMC are working on systems that will eventually replace many elements of the SPYDER® system in building data sets in near-real time from the data that we are receiving electronically. (See the article in the previous Electronic Newsletter). Additionally our plan is to begin relying on data received by electronic methods to automatically add to any of the new FARM data sets. Our goal is to develop techniques that automatically ingest data in real time, or by delayed methods such as ftp, from all sources of data at the DMC. Data will be made available through automatic methods and not rely on the intervention of DMC technicians in most cases.
By shifting to electronic data handling, the DMS intends to increase the amount of data it handles, provide it more reliably and more timely, without increasing operations staff. So far this strategy to improve efficiency has been working well within the IRIS Data Management System.
by Tim Ahern (IRIS Data Management Center)