COMMON QUESTIONS

These guidelines cover how to install seismometers in vaults, pits, and temporary stations. They explain how, to ensure accurate seismic recordings by maximising ground coupling, minimising environmental interference, and properly leveling, orienting, insulating, and securing the instrument for stable long-term operation.

These guidelines outline best practices for designing, drilling, and equipping boreholes for seismometer installations, emphasizing optimal site selection, geological suitability, stable coupling, proper casing and cementing, and noise minimisation, to ensure high-quality, low-noise seismic data from Güralp Systems instruments.

This page provides detailed guidelines for installing Güralp 3T seismometers, whether in vaults, pits, or temporary setups, to ensure accurate seismic recordings by maximising ground coupling, minimising environmental interference, and properly leveling, orienting, insulating, and securing the instrument for stable long-term operation.

This page provides a complete guide to unpacking, testing, installing, and recovering Güralp 6TD seismometers, lightweight, self-levelling instruments designed for rapid, low-maintenance seismic deployments, covering everything from initial setup and multi-unit testing using the transport case to quick field installation, reliable data collection, and safe retrieval.

This page describes techniques for grounding sensor equipment which have proved effective in many installations. However, local conditions are always paramount, and you should design your installation with these in mind. Any regulations in force at your chosen location must also be followed.

This page guides you on how you can determine the exact orientation of a sensor relative to a surface reference sensor, which can be installed on an accurately-surveyed North/South line.

This guide explains how you can minimise sensor tilt, mass position and digitiser offsets.

This article explains cross-axis rejection.

This page discusses two concepts in analogue signal transmission: “single-ended” and “differential”. While digital signals are relatively tolerant of interference, analogue signals can be disrupted and altered by electromagnetic waves in the environment. As well as explaining the problem the page also describes a solution.

This short guide is intended to help you install GPS equipment for timing purposes.

This document explains how to maintain accurate GPS timing for Güralp DM24 digitisers when using long cables—detailing the electrical and signal problems caused by distance and outlining solutions such as using thicker or doubled power cores, DC-DC converters, TIA-422 line drivers, or fibre-optic links to ensure reliable, low-loss signal transmission over distances up to one kilometre.

Poles and Zeros for all Güralp instruments are obtained by the frequency response of the instrument. They are measured using the HP spectrum analyser and a curve is then fitted to this data. All poles and zeros supplied with Guralp equipment are derived from actual measured data and not generated from examination of theoretical calculations.

The nominal phase and amplitude response of a seismometer at different frequencies is described by a set of numbers known as the poles and zeroes of the transfer function. When you measure the response of an instrument using a broadband noise calibration, the Scream! calibration add-on can display the nominal response curves on the same graphs as the measured response curves.

Calibrating with broadband noise provides a convenient way to determine the complete amplitude, frequency and phase response of an instrument in a single experiment.  The Güralp DM24 digitiser includes a pseudo-random number generator and 20-bit DAC which can be used to generate broadband noise with a flat frequency profile throughout the passband of the instrument.  An extension to Scream allows the user to analyse and plot the results. 

Guralp digitisers provide calibration signal generators to help you set up your sensors. Calibration is most easily done through a PC running Guralp’s Scream! software, but you can also do it using a handheld control unit (HCU) and an oscilloscope. Depending on the digitiser type, sine-wave, step and broadband noise signal generators may be available. In this article, we will use a sinusoidal input signal to determine the sensor response at a single frequency of interest.

Güralp digitisers provide calibration signal generators to help you set up your sensors. Calibration is most easily done through a PC running Guralp’s Scream! software, but you can also do it using a handheld control unit (HCU) and an oscilloscope.

These guidelines explain how to protect seismic installations and data networks by combining physical safeguards, tamper detection, encrypted communications, and controlled user access. This will ensure Güralp Systems’ instruments and configurations remain secure from theft, interference, or accidental reconfiguration while maintaining reliable data integrity.

Güralp sensors and digitisers include comprehensive triggering facilities, which allow you to record seismic events in detail as they occur.

In this guide, we will consider a Güralp digital sensor connected to a central recording station over a dial-up link. This link is too slow for real-time acquisition at high data rates. When an event occurs, we want the sensor to record high-rate data and save it in its Flash memory, so that it can be downloaded over the dial-up link at a later stage.

This guide explains the different ways to connect to a DM24 digitiser (or a sensor incorporating a digitiser module) with a modem.

Guralp Systems digital equipment can operate in one of several transmission modes. These modes relate to how the unit uses its Flash memory.

Guralp digitisers and digital instruments can be supplied with external triggering capabilities installed. The external trigger system is designed for maximum flexibility: you can trigger other digitisers or your own equipment using built-in relays and any equipment may be used as a trigger source, using the built-in opto-isolator.

Güralp DM24 digitisers are available in three-channel and six-channel versions. (Both actually have an additional full-specification input channel so you may also see them referred to as four-channel and seven-channel units.) 

A six-channel DM24 can be configured to appear either as a single six-channel system, with a single System ID and Serial Number (used to identify the streams), or as two virtual three-channel digitisers, sharing a single System ID but with two separate, distinct Serial Numbers. The only differences between the two modes are the names of the resulting output streams.

This document explains how to configure each of the modes and how to switch between them.

In order to alert listeners that an event is in progress, the datalogger implements a ground motion notification mechanism. This mechanism implements a message bus over TCP which carries notifications as messages.

This document applies to systems running the Platinum operating system. This includes acquisition systems such as EAMs and NAMs, digitisers such as Affinity systems and DM24SxEAMs and digital instruments with embedded acquisition modules such as 3TDEs, 40TDEs and 5TDEs.

The DM24 has a 1kb buffer inside its firmware, which can be used to store information about attached sensors. Users are free to store any data they wish in the digitiser’s information block.

Typically, this is used to store calibration parameters, poles and zeroes, etc. Newer digital sensors have their calibration information pre-loaded into the information block, in the format described below. DM24mk3 instruments use this information to perform their strong motion calculations.

It is useful to be able to find out, for a given block of seismic data, what filters have been applied to it to get it into its present form.

DM24, CD24 and Affinity digitisers set a byte within every block of GCF data, which identifies the sequence of filters in use.

NOTE: THIS LINK WILL FIRST TAKE YOU TO A LICENCE ACCEPTANCE PAGE

This information applies to most modular DM24 units and digital instruments manufactured after 2004.

NOTE: THIS LINK WILL FIRST TAKE YOU TO A LICENCE ACCEPTANCE PAGE

This information applies to all 6TD and EDU systems manufactured after 2005. These digitisers are single-channel units based on the CD24 compact digitiser module. It also applies to stand-alone CD24 digitisers.

NOTE: THIS LINK TAKES YOU FIRST TO A LICENCE ACCEPTANCE PAGE

This information applies to all CMG-DM24 units manufactured before 2004, and any Mk2 units manufactured after that date.

This document describes the sequence of FIR filters used by older 6TD instruments manufactured before the introduction of the CD24 digitiser.

NOTE THIS LINK WILL TAKE YOU FIRST TO A LICENSING ACCEPTANCE PAGE

Güralp Systems digital instruments and data modules use Güralp Compressed Format (GCF) to share seismic data. The format is used both for data storage and for data transmission over serial links or TCP/UDP networks. Two protocols, the BRP protocol and the scream protocol, are used for transmitting GCF data.

This guide explains how to convert seismic data from Guralp Systems instruments into the formats required by different analysis packages. Depending on your application, data streams can be converted in real time, or saved in GCF format and converted to your preferred format later.

This guide explains how to extract data from a GCF file by using the “View” mode of Scream!.

Güralp provide a number of GCF file format conversion utilities to help with protocol conversion and common data management tasks you can access these in the Firmware and Software area.

GCF data from digitisers are identified by the combination of System ID and Stream ID. The “System ID” identifies the digitiser from which the data originate and each stream from a given digitiser is then identified by its “Stream ID”. Each Stream ID is composed of two parts, the “Serial Number” and a two-character suffix to identify which data are contained in the stream.

Scream is designed to work as a robust part of your seismic network. By default, it uses the configuration file scream.ini to set itself up automatically when restarted. However, in certain circumstances you may want to run two or more instances of Scream simultaneously on the same computer, with each instance having a different configuration.

The following procedure creates a shortcut with stored command-line arguments. This makes it easy for you to start Scream with the same arguments every time or, by placing the shortcut in your Start-up folder, to start Scream automatically every time you log on. It is also the simplest way to regularly start Scream with a different initialisation file, which is required if you wish to run more than one copy of Scream simultaneously.

Scream! allows you to explore seismic waveforms by zooming and scaling, and also has the ability to display time series in physical units. This how-to explains the differences between these features.

Scream! allows you to apply filters of your own design to WaveView windows. Each WaveView window can have its own filter settings, either using a preset filter or one you have designed. You can use this feature to view the same data in several frequency ranges at once.

It is often necessary to install additional libraries in order to run Scream! and the other Güralp linux tools, such as gcf2msd or gcf2sac on 64-bit Linux platforms. The precise details vary between distributions but most will follow either the Debian/Ubuntu model or the Red Hat/Fedora/CentOS model, for which details are given below.

The Linux build of Scream! is intended to work with many different Linux distributions. For this reason, it does not include any distribution-specific features. It is usually possible to perform a few post-installation steps which improve the integration of Scream! with the host operating system. This document describes how to integrate Scream! into the Ubuntu Dash, which makes it behave more like a Ubuntu-supplied application.

DM24 and CD24 digitisers have a 1kb memory region which can be used to store information about attached sensors and the digitisers themselves. Users are free to store any data they wish in the digitiser’s information block.

Typically, this is used to store calibration parameters, poles and zeroes, etc. Newer digital sensors have their calibration information pre-loaded into the information block. DM24mk3 instruments use this information to perform their strong motion calculations.

Scream! uses its own protocol for transmitting seismic data over the Internet. The Network Control window within Scream! lets you manage a seismic array with multiple data sources, using this protocol.

When requesting technical support, you may sometimes be asked to provide a copy of your scream.ini file. There is no restriction on where this file can be placed so this document is intended to help you locate it. Once you know its location, you can simply attach it to an email.

When Scream! is installed, it adds a number of items to the Windows explorer context menu – the menu that appears when you right-click on a GCF file – including the “View with Scream” option.

There have been a few reports of this facility being broken. In these cases, right-clicking on a GCF file will produce a menu with the normal Scream context menu items missing.

This document describes a procedure by which the missing context menu items can be restored on a Windows 10 PC.

This article will help you diagnose problems with a DM24 Mk3 digitiser, where

• you are not receiving any data streams,
• the digitiser does not appear in Scream’s main window, and
• you have checked that the communications link between your computer and the digitiser is working.

This article will help you diagnose problems with a legacy DM24 Mk2 digitiser, where

• you are not receiving any data streams,
• the digitiser does not appear in Scream’s main window, and
• you have checked that the communications link between your computer and the digitiser is working.

The DM24 digitiser is available as a stand-alone unit, integrated into instruments (such as the 5TD) and integrated with acquisition modules (such as the DM24S3EAM or the older DM24S3DCM). The DM24 underwent a significant design change in late 2005, when the Mk3 was introduced, but there are still many Mk2 units installed and giving good service. The two versions require different firmware. This page describes how to tell whether you have a Mk2 or a Mk3 DM24 digitiser.

This guide applies to DCMs running their native firmware. Güralp Systems Ltd recommend that all DCMs are upgraded to run Platinum firmware. This guide does not apply to DCMs that have been upgraded.

The file /var/log/messages contains important diagnostic information about your Platinum system. Technical support staff may occasionally request that you send them a copy of this file to assist in diagnosing problems with your system. This document describes a number of ways in which you can do this. All of these methods involve first copying the file to a PC, from where it can be sent via e-mail.

The earth's rotation is gradually slowing in an unpredictable manner. It is affected by, amongst other things, large earthquakes and volcanic eruptions. These alter the distribution of mass around the planet and, because angular momentum must be conserved, the rate of rotation must change, altering the duration of a day.

If you choose to install ART 3 along with Scream on a Windows 10 or 11 PC, you may see an error message saying that the .NET Framework is not installed. This can be misleading because it can occur even when the one or more versions of .NET are are already installed.

When requesting technical support, you may sometimes be asked to provide the I.P. address of the PC on which you are working. This document explains how to find this information for PCs running various different operating systems.

It is sometimes awkward to connect a Platinum system, such as an EAM or 40TDE instrument, to the Internet for remote assistance. For example: in some cases, the only available Internet access is via WiFi so, if the Platinum system does not have a WiFi interface, direct connection becomes impossible. In these cases, a PC or laptop can be used as a gateway, allowing the Platinum system to contact the Güralp remote-assistance server indirectly, via the PC.

If you suspect problems with digitiser operation or configuration, including GPS/GNSS problems, Güralp support may request that you send a status recording illustrating the problem. This page describes the sequence of actions required in order to make an effective, complete recording of the boot-up messages from a Güralp CD24 or DM24 digitiser.