Seismic Instruments
S•Geophone (SmartGeophone, SMG)
FUNCTION
- Signal conditioning and digitizing of seismic signals
- Interpretation of command, returning status and geophone reponse in digital format via a twisted quad wire telemetry bus
- Tests the performance of each geophone and electronics
PHYSICAL
- Lightweight, watertight, rugged housing
SPECIFICATIONS
- Input Impedance 1KΩ damping (>25 without damping), || 5nF
- Preamp Gains 0dB, 12dB, 24dB, 36dB
- Full Scale Input Levels
- 0dB 5Vpp
- 12dB 1.25Vpp
- 24dB 312.5mVpp
- 36dB 78.1mVpp
- Offset digitally zeroed at all gains
- Sampling Interval 0.25, 0.5, 1ms, 2ms
- Bandwidth (-3dB) 428Hz
- Stop Band Attenuation
(above Nyquist measured -6dB below full scale) >130dB - Passband Ripple (below 400Hz) 0.01dB
- Passband Phase Characteristic linear
- Signal to Noise Ratio
(RMS to RMS, 800 Ohm terminated input)
0dB 123dB (typ) >120dB
12dB 122dB (typ) >118dB
24dB 115dB (typ) >112dB
36dB 103dB (typ) >100dB
- Total Harmonic Distortion
(measured -6dB below full scale, 31.25Hz)
0dB 115dB (typ) >110dB
12dB 110dB (typ) >100dB
24dB 110dB (typ) >100dB
36dB 100dB (typ) >90dB - Gain Accuracy (absolute) 1% (typical)
- Gain Accuracy (relative at different gains) 0.4% (typical)
- Power Consumption 250mW (typical)
- Operating Temperature -40ºC to 75ºC
S•Geophone String (SMG String)
Multiple SMG sensors wired together comprise an SMG String.
An SMG string consists of four basic components:
- A string connector
- SMG's
- Cable segments
- String terminator
Due to the modular design of the SMG string, individual components may be easily removed and replaced. Although SMGs are wired together, each sensor returns data separately from the others.
In a conventional analog geophone string, sensors are electrically wired together in a serial and/or parallel manner. This means that one improperly planted or damaged conventional sensor could corrupt the data from an entire string. On the other hand, with the SMG String each SMG returns its data separately from the rest of the SMG sensors providing complete data isolation from one sensor to the next.