CTA - STATION INSTRUMENTATION
1.High-Gain Long-Period Seismograph System-HGLP: [HG]
Dates of Operation: 11 Aug 1972 to 29 Aug 1976.
SEISMOMETER TYPE:
Teledyne-Geotech long-period 3 component system, Model S-11 vertical and two
Model S-12 horizontals. Seismometers are located in sealed metal tanks filled
with argon gas.
DIGITAL FORMAT:
16 bit integer data words for all components. Range: +32767 to - 32768 counts.
EVENT DETECTOR ALGORITHM: None.
Click on any of the following items for further information
COMMENTS:
The HGLP Seismograph Network was the first global network of digitally recording
seismograph stations. Installations began in August, 1972, and the last system
was closed in 1979. The initial hardware included long-period phototube amplifiers
(PTA) which had inherent drift problems which in turn affected the calibration. The
PTAs were replaced with Ithaco amplifiers in early 1975 which resulted in a standard
response curve for the HGLP Network. All of the data was recorded on 7 track magnetic
tape. In 1985 all of the HGLP data was rerecorded on 9 track magnetic tape in SRO
format. This data is now available in the SEED format, however, it should be noted
that the calibration for much of the data is suspect.
The Ithaco amplifiers were installed at CTA on 27 Feb 1975.
Seismic background noise is identical to CTAO.
