Trillium Compact Posthole

Nanometrics industry-leading portfolio of Trillium seismometers now includes a Trillium Compact Posthole for quick and easy deployment.

Available in both 120s and 20s variants, the Trillium Compact Posthole features a stainless steel enclosure and waterproof connector ideally suited for downhole deployments.




Specifications are subject to change without notice.

Topology Symmetric triaxial
Feedback Force balance with capacitive transducer
Mass centering Not required
Sensitivity - 120s 750V-s/m nominal ±0.5% precision
Bandwidth - 120s -3 dB points at 120 s and 100 Hz
Sensitivity - 20s 750V-s/m nominal ±0.5% precision
Bandwidth - 20s -3 dB points at 20 s and 100 Hz
Off-axis sensitivity ±0.5%
Transfer function

Lower corner pole frequency within ±0.5% of nominal provided

High-frequency poles within 1 dB of nominal up to 45 Hz

No peak in response at high frequency

Clip level 26 mm/s from 0.1 Hz to 10 Hz
Operational tilt range - 120s ±2.5°
Operational tilt range - 20s ±10°
Parasitic resonance None below 200 Hz
Dynamic range >152 dB @ 1 Hz
Connector - downhole 16-pin, underwater SubConn MCBH16MSS, top mounted
Velocity output

±20V peak (40V peak-to-peak differential)

Selectable XYZ or UVW mode

Mass position output

Single voltage output representing maximum mass position

3-channel mass positions available through serial port

Calibration input

Single voltage input and one active high-control signal to enable all 3 channels

Remote calibration in XYZ or UVW mode

Independent channel selection by serial port

Digital interface

RS-232 compatible serial IP (SLIP)

Onboard web server standard HTTP

Digital commands

XYZ, UVW mode switching

Calibration channel selection (off, enable all, U, V or W)

Short/long period mode

Firmware updates

State-of-health request

Digital data outputs

Independent mass position values

Instrument temperature

Factory sensitivity

User calibration data (poles and zeroes)

Instrument serial number and firmware revision

Diameter 97 mm 

160 mm  (body and connector)

167 mm (on fixed studs)

230 mm (on optional 70 mm spikes)

Weight 3.3 kg
Housing Stainless steel surface, resistant to corrosion, scratches and chips

Vertical scribe marks for N/S

Case-top north/south guide for straight-edge, line, or laser level

Immersion rating Rated to IP68 for full submersion
Supply voltage 9 to 36 V DC isolated inputs
Power consumption

<180mW typical (model TC120-PH2)

<195mW typical (model TC20-PH2)


Reverse-voltage and over-voltage protected

Self-resetting over-current protection revision

Operating temperature -20°C to +60°C (ultra-low temperature option available, contact Nanometrics)
Storage temperature -40°C to +70°C

100 g half sine, 5 ms without damage, 6 axes

No mass lock required for transport

Magnetic Insensitive to natural variations of the earth's magnetic field


Self-Noise Performance Plot