Here are some of the articles that have been recently posted to the PASSCAL website:

SmartSolo archives flipped polarity (IGU-16HR 3C 5Hz)

Dear EarthScope Community and EPIC PIs:

In September of 2023 we discovered that SmartSolo node (IGU-16HR 3C, 5Hz) data archived from EPIC experiments has a non-standard polarity on the Z-channel relative to the down-positive industry geophone convention. Details of this discovery and the steps that will be taken to correct this discrepancy, which will affect the existing and future archives, are outlined below.

Issue

The expected polarity for data archived from EPIC experiments are as follow:

Broadband seismometer – Up (Z-dip = -90), North and East motion produce a positive polarity. Geophone – Down (Z-dip = +90), North and East motion produce a positive polarity

Data archived, both PH5 and SEED, prior to October 05, 2023 from EPIC experiments using the SmartSolo nodes have the following polarity and metadata mismatch: 

Important Hardware/Software Notes for Researchers Using EPIC Equipment

This page includes important Hardware/Software Notes for Researchers Using EPIC Equipment. January 17, 2019: GPS Rollover

Late 2018 EPIC learned of a GPS week rollover event that can affect data logger performance and timing. EPIC has acquired a GNSS signal generator that can emulate GPS satellite signals. This satellite emulator allows us to test EPIC equipment that relies on GPS timing and to determine how equipment will handle the GPS rollover event. To date, we have determined that some models of GPS engines are affected by the rollover. How the rollover errors manifest is dependent on the data logger’s model and firmware version of the GPS engine.

Controlled Sources

The Propelled Energy Generator, model: PEG-40Kg

Multi-Channel Dataloggers

EPIC’s current inventory of multi-channel dataloggers, which now serves as our primary system for active source surveys using geophones, is centered around the ES-3000 Geode and a 60 Channel Strata View NZXP.  The ES-3000 offers reliable performance, portability, and compatibility with EPIC’s existing multi-channel cable systems, originally designed for earlier Geometrics models.

3-Channel Dataloggers

Quanterra Q330

Q330's are typically used for broadband standalone and telemetered real-time data recording. They have an external storage device (either hard drive or USB flash drive) and lend themselves for a variety of telemetered modes.

 

Reftek RT130

Dataloggers

A datalogger (also know as data acquisition system or DAS) is piece of electronic equipment which converts an input into a digital time series representation. Immense care should be taken when setting up and programming a datalogger. It is highly recommended that only experienced users program their own dataloggers and all others should consult a EPIC staff member for assistance.

While specific procedures and programming details will vary between the various types of dataloggers, there are several things that hold true when working with any datalogger.

The datalogger should be:

Seismic Vaults

Introduction:

The construction of the vault for broadband seismometers has a direct impact on the data quality. The principle of broadband sensor vault design is to minimize temperature changes, and to distance the sensor pad from the surficial layer which tilts due to temperature, precipitation, solar insolation, wind, etc.

Nearby sources of ground noise, like footsteps or acoustic noise, are reduced by shallow burial (2-5 ft.) The construction must be adapted to the site and materials available. A decision will have to be made to balance the cost and labor of different vault designs against the length of deployment, resources available, and quality of data expected.

Finding a pre-existing enclosure is a tremendous savings in time and effort. This might include missile silos, power stations, abandoned mines, caves, or root cellars. Consider the details of cables, power, and locating a GPS antenna for timing at these sites.

Station Installation

EPIC can help guide you through various aspects of Station Installation, including Tasks, time required, crew considerations, and Suggested Materials. For broadband experiments the PI and students come to EPIC for several days of training before your experiment's field campaign begins. During the training session details of the experiment's logistic and climatic conditions are discussed and considered for the station design and installation procedures.

TASKS: Tasks depend on the station design, but the task list for a typical broadband station would be the following.

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