Broadband Seismometer "Observer"
Supplied By: Reftek Trimble, USA
Broadband Seismometer "Observer" Model 151B-120 / 151B-60 / 151B-30 - Introduction
The 151B series Broadband Seismometer, “Observer”, is a force-balance feedback sensor available with frequency bandwidth 0.0083 Hz (120 sec) - 50 Hz, and 0.016 Hz (60 sec) - 50 Hz and 0.033 Hz (30 sec), flat to velocity. The 151B “Observer” contains three independent sensors (one vertical and two horizontal) with built-in electronic feedback circuit, control and power conversion circuits, featuring low noise, large dynamic range and easy installation and use.
The 151B Observer has built-in leveling and mass lock/unlock facilities. The leveling mechanism includes two bubble levels, three adjustable feet and three locknuts which are located on the seismometer’s chassis (see photo below).
The 151B Observer has built-in mass zero-position adjusting mechanism to perform automatic mass adjustment. As soon as the seismometer is powered it checks the zero position of each component’s mass and automatically adjusts the zero position if needed. Monitoring and adjustment of the mass can also be performed via the 130 family High Resolution Recorders using Sensor Control Board, RT527-B01.
The 151B Observer is a low noise seismometer (see below Power Spectral Density plot). The low self noise performance makes the 151B-120 an ideal seismometer for local, regional, and global seismicity studies in different installation configurations, including observatory and portable, surface and posthole applications.
Local and Regional
Broadband Surface or Posthole Installation
High Performance Broadband Seismometer
Low Self-Noise Over a Wide Bandwidth
Low Power Consumption
Force-Balance Electronic Feedback
Robust Mass Locking Mechanism
Noise Model for REF TEK 151B
|Sensor Type||Triaxial, orthogonal|
|Feedback||Force balance with capacitive displacement transducer|
0.0083 Hz (120 sec) - 50 Hz (see diagram in manual), Model 151-120
0.0166 Hz (60 sec) - 50 Hz, Model 151-60
0.033 Hz (30 sec) - 50 Hz, Model 151-30 (optional upon request)
|Output Impedance||+/- 20 V peak-to-peak differential|
|Calibration||Coil resistance 1,000 Ohms, sensitivity: 10 m/s2/A|
|Levelling||Two Integrated bubble levels. Three adjustable leveling feet with locknuts|
|Mass Position||Remote monitoring and adjustable zero-point using 3 independent voltage outputs|
|Mass Locking||Mechanical lock/unlock on outside of the case|
|Distortion||Total distortion less than -80 dB|
|Cross Axis Coupling||Less than 1%|
|Mechanical Zero||No need for adjustment within ambient temperature fluctuation +/- 20o C|
|Signal Overload Protection||Built-in|
|Auto-recovery Time||Full operation recovery within 10 minutes after either power fail or signal overload|
|Supply Voltage||9 to 18 VDC|
|Operating Temperature||-20o C to +60o C|
|Power Consumption||~ 1.1 W|
|Water Tight Integrity||IP67 for outdoor use and immersion resistance|
|Case||Aluminum, Powder Coated|
|Dimensions||Diameter: 9.45 " (24 cm); Height: 10.6 " (27 cm)|
|Weight||26.4 lbs (12 Kg)|
|Alignment||Removable orientation North(brass) / South(silver) pins screw into the base|
|Accessories (optional)||Rugged transportable hardigg case. Flexible insulation bag (P/N 151-9800)|
151B Standard Observer Kit
The 151B Standard Observer kit includes:
T-type Allen wrench key for levelling
Aluminium carrying case with pre-cut foam
151B Optional Ruggedized Transport Case
The 151B Observer is available with an optional ruggedized transportation case and thermal insulation bag.
The 151B Observer's transportation case is a ruggedized, durable, lockable case with handles and removable casters, designed for multiple shipments by any means of transportation in a harsh environment.
The transportation case has pre-cut foam to house the 151B Observer with carrying case, removable casters and accessories, including sensor cable and thermal insulation bag.
The 151B Observer's thermal insulation bag is fabricated from Microfleece material with primaloft insulation, providing protection from wind and daily temperature fluctuations in the vault to insure the highest quality data.