Observatories and Research Facilities for EUropean Seismology
Volume 1, no 2 April 1999 Orfeus Newsletter


FDSN WG on data exchange: Meeting December 4, 1998, Seattle, USA

Reporter chairman Bernard Dost
ORFEUS

SEED issues - FDSN archive status - Status AutoDRM
NetDC - SPYDER® - VSAT - WILBER - Miscellaneous

SEED issues

A proposal was received to introduce blockette 62 and 49. The purpose being to describe the response of a non-linear and non-flat linear device, like a pressure or temperature sensor. Since the proposal was new to most of the WG members, it was decided to have a look at it and report to me back before January 15, 1999 in case there is any problem with the introduction of these blockettes. No response was received at this date, so the proposal is accepted.

A proposal was tabled for the post archiving of timing corrections, enabling a correction to (mini)SEED data records in a mass storage system. The change requires only the use of one previously unused bit in the data header, so the impact is assumed to be minimal. Again, since the proposal was coming in at the meeting, members were solicited to give their comments by email before January 15, 1999. No response was received at this date, so the proposal is accepted. (link to the email document is pending)

Until now the Network Codes (NCs), which are provided by IRIS, are only using upper case characters. There was a concern that network codes could run out and it was proposed to also include lower case characters. Tim Ahern reported that he would strongly discourage the use of case sensitive NCs and he offered to review the concern on the limits on the NCs.

In the conversion from GSE 2.X data to SEED the original instrument response may be defined in the form of frequency-amplitude-phase (FAP) numbers. In SEED poles and zeroes are required. The question was raised if SEED could also accept only FAP information. Bernard Dost strongly argued against this, since users will have to make their own adaptation to poles and zeroes if they want to correct for instrument response, initiating a multitude of responses for the same instrumentation. Also, there is a tendency to process large data volumes in an automatic fashion and the conversion from FAP to poles and zeroes can not easily be automated.

A brief discussion started on additions and/or changes in the SEED format needed to incorporate strong motion data in SEED. One problem is the channel naming convention and it was proposed to use an unused letter. No definite conclusion was reached, but the issue is open for discussion.

Tim Ahern will check the use of orientation code for electromagnetic recording in SEED. He also encourages people to look at the electronic version of the SEED manual, since changes, like proposed at this meeting, will be available only in the electronic version for quite some time.

FDSN archive status

The USGS/NEIC operates the FDSN event-oriented archive and produces FDSN CD-ROMs. Kay Shedlock noted that volume 5 (first 3 months of 1991) was in press and the rest of the 1991 data would be ready in the next few months. The event data, that are retrieved from the FDSN continuous archive at the IRIS DMC, are ready until May 1992. Requests from the USGS until the end of 1993 are in and will be serviced in 1999.

The continuous FDSN archive is collecting most data routinely, but there are a few important issues. First of all, MedNet sent its data until November 1995 and has a considerable delay. It was not known in detail if data from stations, which do not belong to a major network, do come in regularly and if there are any issues. The Australian data may be a problem, as well as the Mexican FDSN stations.
ACTION: A list should be compiled of FDSN stations that are having trouble to contribute their data in time. (link status report pending)

Tim Ahern prepared a handout concerning FARM volume production by FDSN members. (link document is pending).

It was suggested to start thinking about moving from CD-ROMs to DVDs in the near future. The good thing is the increase in data storage. The bad news is the absence of a real standard for data storage at DVD. In summer 1999 new developments are expected that may bring the use of this technology closer.

Status of (auto)DRM installations and usage

This item could best be exploited when there is a fdsn website. Inventories and direct links should be set-up and maintained. At Orfeus a list for Europe is presently being maintained. AutoDRM was adapted by Reinoud Sleeman to transfer SEED volumes in March 1999.

NetDC

Rob Casey gave an overview of the philosophy behind NetDC. The status of the software is that experiments are being carried out with Berkeley to test the current implementation and to further develop the code. In March/April 1999 Rob Casey came to Europe to implement the software in Paris and de Bilt. The software will be tested in summer 1999. GFZ Potsdam decided not to take part at this stage, since they lost their programmer.

SPYDER® status and developments

SPYDER® now builds SEED volumes and it has a Y2k problem in using MLINK. Alternatives are being looked at and Peter Burkholder at the University of Washington is tackling the problems.

VSAT usage

Satellite transmission is gaining importance in the rapid exchange of waveform data. In Europe a large network of broad-band stations is being installed in Spain, using VSAT as their main means of data transmission. Could other data centers use these data, when equipped with a satellite dish?

The understanding was that VSAT is a point to point protocol and that multicast is not yet developed. One should keep an open eye on developments in this field.

WILBER distribution

WILBER is installed in April 1999 in Paris and de Bilt.

Miscellaneous

IRIS proposes to set up listservers for the WG's and Tim Ahern is going to arrange a "fdsn.org" name.

Genevieve Roult argued to cut the response plots in the station book at the Nyquist frequency. This was accepted.

The question was raised if the FDSN should consider to use CD-1 or CD-2 as a continuous format. It was decided that the format should be evaluated and comments discussed in the next WG meeting.

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