Geophones GS-20DM

GS-20DM

The Small Digital Grade Geophone

The GS-20DM Small Digital Grade Geophone fills the need for reducing the weight and volume of geophone strings. Through a design that includes total internal damping and the use of smaller and stronger magnets, the weight and size of the GS-20DM have been reduced by approximately 50% while maintaining the same performance characteristics of the traditional larger geophones.

The GS-20DM header has the patented and ultrasonically welded PCB for strong cable anchoring and reliable electrical contact. This design, with rotating coil construction, silver plated contacts and gold plated springs, assures long field life and parameter stability.

The geophone operating parameters are checked and confirmed with a proprietary computerized test system during the manufacturing process. Each geophone string has a brass tag with a serial number to identify its computerized test records. The GS-20DM basic unit has a two year warranty.

Cases Available

The GS-20DM has the industry’s widest choice of waterproof horizontal and vertical cases, land and marsh cases, as well as cases for use with 2D and 3D configurations.

Spec Sheet:

At 25° C
Natural Frequency (Fn):
10 Hz
14 Hz
28 Hz
40 Hz
Maintains Fn Specifications to Tilt Angle of
20°
20°
90°
90°
Typical Spurious Frequency
>300 Hz
>400 Hz
>600 Hz
>850 Hz
Harmonic Distortion with Driving Velocity of 
0.7 in/sec (1.8 cm/sec)P-P
<.3%
<.3%
<.3%
<.3%
Distortion Measured at
12 Hz
14 Hz
28 Hz
40 Hz
Maintains Specifications to Tilt Angle of
20°
20°
90°
90°
Open Circuit Damping (Bo) (for all coil resistances)
.70
.70
.60
.42
Standard Coil Resistance (Rc) ± 5%
280 ohms
240 ohms
270 ohms
270 ohms
Intrinsic Voltage Sensitivity ± 7%
V/in/sec
.500
.450
.384
.384
V/cm/sec
.197
.177
.151
.151
Optional Coil Resistances (Rc) ± 5%
65 / 435
56
110
110
Damping Constant
1.37 Rc
.95 Rc
.43 Rc
.30 Rc
Normalized Transduction Constant
V/in/sec
.030 (sq. root Rc)
.029 (sq. root Rc)
.023 (sq. root Rc)
.023 (sq. root Rc)
V/cm/sec
.012 (sq. root Rc)
.011 (sq. root Rc)
.009 (sq. root Rc)
.009 (sq. root Rc)
Moving Mass ± 5%
8.0g(.28 oz.)
7.8g(.28 oz.)
5.6g(.20 oz.)
5.6g(.20 oz.)
Case to Coil Motion P-P
Min
——1 mm (.04 in)——
Max
——2 mm (.08 in)——
Operating Temperature Range (°C)
——- 45° to +100° ——
Dimensions (less terminals*)
Height
——2.64 cm (1.04 in) ——
Diameter
——2.22 cm (.875) ——
Weight
——43 g (1.5 oz.) ——
Specifications are subject to change without notice.

GS-20DM Seismic Detector Response Curve
Output vs. Frequency Chart

 

Specifications are subject to change without notice.

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