In February 2005, we terminated operations of the Potrero Hills site POTB, which had been operating since December 1998, as well as the collocated seismic instrumentation, due to the transfer of property ownership. The operations of BARD stations at Chabot (CHAB) maintained by the USGS, and SLAC maintained by the Stanford Linear Accelerator were transferred to the Plate Boundary Observatory in May 2005. The SLAC receiver replaced the nearby SUAA receiver that Stanford formally stopped maintaining during this last year. As part of our colloboration with the Hat Creek Radio Observatory, we swapped the HCRO GPS receiver several times during the year to facilitate their use of RTK instrumentation. HCRO will transfer to the PBO network in Fall 2005. We are currently planning to install a new GPS station as part of the completion of the Marin Headlands (MHDL) Mini-PBO station in Fall 2005, which has been awaiting the establishment of AC power.
We improved data telemetry at several stations during the last year. Replacement of a corroded cable allowed data from BRIB to be telemetered via the collocated Quanterra data logger. The Cylink radios used for FARB was replaced with a Wi-Lan radio as part of a reconfiguration of the telemetry paths through UC San Francisco rather than Mount Tamalpais. As part of this reconfiguration and coincident with the replacement of a badly rusted antenna mast, the Freewave radio path at PTRB was adjusted to pass through UCSF, although data recovery was hampered for several months by problems with an improperly oriented radio antenna.
We also performed routine maintenance at several sites during the year, including replacement of cables and batteries at the GRIZ and VOLM L1-profile stations, and replacement of a failing Ashtech Z-12 receiver at YBHB November 2004. Several Ashtech uZ receivers have also failed by progressively recording few and fewer satellites, first at OXMT in 2003, then at OHLN in August 2004, and more recently at SVIN. Ashtech believes that a bad capacitor was installed in this series of receivers. These receivers will be repaired in Fall 2005.
Berkeley Seismological Laboratory
215 McCone Hall, UC Berkeley, Berkeley, CA 94720-4760
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