Netherlands 2008-2013

Used equipment



The seismometers used in the NARS Netherlands project are the Nanometrics Trillium 120P and the Streckeisen STS-2 broad band sensors. Both are electronic force-feedback sensors that provide an output signal proportional to ground velocity over a broad frequency range. Three identical obliquely-oriented mechanical sensors are used and standard vertical and horizontal outputs are derived by summing the raw sensor signals within the sensors electronics. The housing is vacuum-tight and designed to minimize the distortion of the package by barometric pressure changes.The sensors are designed for quick and simple installation, wide temperature range operation, and secure transport, while resolving minimum earth noise levels over the frequency range.


Key features Trillium 120P:

Generator constant:
Electronic self-noise:

Seismic signal output:

Power input:
Power consumption:
Temperature range:
For more information:

1200 V*s/m ±0.5%
4 dB above the NLNM at 100 seconds and below the NLNM up to 10 Hz
-3 dB points at 120s and 145 Hz
40 V peak-to-peak differential; Selectable XYZ or UVW mode
9 to 36 volts DC isolated input
650 mW typical at 15 V input
±45°C without re-centering


Key features STS-2

Generator constant:
Electronic self-noise:


Seismic signal output:
Power input:
Power consumption:
Temperature range:
For more information:

1500 V*s/m
Approx. 6 dB below USGS low-noise model between 5 mHz and 15 Hz
Ground velocity between corners 8.33 mHz (120 sec) and 50 Hz
±20 V differential range
10 - 30 V DC
Average 1.0 W
±10 C without mass recentering
Streckeisen AG, Messgeraete, Daettlikonestrasse 5, CH-8422 Pfungen, Switzerland. Email: G.Streckeisen AG


For precise timing we use the Trimble Acutime Gold GPS smart antenna. It generates a pulse-per-second (PPS) output synchronized to UTC within 15 nanoseconds, outputting a timing and position packet for each pulse.

Key features of the Acutime Gold:

PPs (puls per second output):
Serial protocols:
Prime power:
Power consumption:
For more information:

UTC 15 nanoseconds (static)
80 nanoseconds
10 microseconds to 500 milliseconds (user-programmable)
Serial RS422/485 or RS232 (cable length up to 300 meter)
TSIP, NMEA or RTCM protocols
+5V DC to +36 V DC
50mA @ 12 Volts, 0.6Watt (typical)
Waterproof, pole mounting
For more information:

Data logger

The Seismology group of Utrecht University together with the Instrumental group of the Physics department, developed the NARS seismic datalogger. The datalogger consists of mainly two components: (1) a data acquisition module, which does the AD conversion and timing. (2) an off-the-shelf embedded computer, for all further data processing. Data is stored on the datalogger's internal hard disk and (optionally) to an external USB stick. All communication with the outside world is done bij network comunication.


The data acquisition module is similar as used with our previous NARS Baja project. For more detailed hardware information visit the NARS Baja equipment page.


By GSM modem, the datalogger sends daily a short message (SMS) to Utrecht University with all important status information. It is also possible to make a GSM data connection and communicate directly with the datalogger system.

Key features of Siemens MC35i Terminal:

Power supply:
Frequency bands:
Transmit power:
GPRS connectivity:

Voice, Data, SMS, Fax
8V to 30V DC
Dual Band E-GSM 900 and GSM 1800
Class 4 (2W) for EGSM900, Class 1 (1W) for GSM1800
GPRS multi-slot class 8, GPRS mobile station class B
MT, MO, CB, Text and PDU mode

Portable computer

For station setup, data collection and communication with the datalogger we use a portable computer running Linux. Communication is established by Ethernet using the virtual console program Xvnc.
For more detailed software information visit the NARS Baja equipment page.