Geometrics.com

Geode Specifications

A/D Conversion: 24 bit result using Crystal Semiconductor sigma-delta converters and Geometrics proprietary oversampling.

DynamicRange: 144 dB (system), 110 dB (instantaneous, measured) at 2ms, 24dB.

Distortion: 0.0005% @ 2 ms, 1.75 to 208 Hz.

Bandwidth: 1.75 Hz to 20 kHz. Low corner frequency option available.

Common Mode Rejection: > -100 dB at <=100 Hz, 36 dB.

Crosstalk: -125 dB at 23.5 Hz, 24 dB, 2 ms.

Noise Floor: 0.2uV, RFI at 2 ms, 36 dB, 1.75 to 208 Hz.

Stacking Trigger Accuracy: 1/32 of sample interval.

Maximum Input Signal: 2.8 VPP.

Input Impedance: 20 kOhm, 0.02 uf.

Preamplifier Gains: SGOS software enables selectable gain pair of either 24 or 36 dB. MGOS software selection between jumpered gain pair 12 and 24 dB, gain pair 24 and 36 dB, or 0dB.

Anti-alias Filters: -3 dB at 83% of Nyquist frequency, down 90 dB.

Pre-trigger Data: Up to 4,096 Samples. Optional event detection software enables system for earthquake, vibration monitoring.

Sample Interval: 0.02, 0.03125, 0.0625, 0.125, 0.25, 0.5, 1.0, 2.0, 4.0, 8.0, 16.0 ms.

Record Length: 16,000 samples standard, 64,000 samples optional 2

Delay: 0 to 9999 ms in 1 ms steps.

Data Transmission: Uses reliable Ethernet connections and requires no custom transmission software. Interfaces directly with Windows OS.

Auxiliary Channels: All Geode channels can be programmed as either AUX or DATA.

Instrument Tests: Optional built-in analog testing available. Tests provided: noise, crosstalk, total harmonic distortion, gain similarity, gain accuracy, common-mode rejection, trigger accuracy

Acquisition and DisplayFilters:
LowCut: OUT, 10, 15, 25, 35, 50, 70, 100, 140, 200, 280, 400 Hz, 24 or 48 dB/octave, Butterworth.
Notch: 50, 60, 150, 180 Hz and OUT, with the 50 dB rejection bandwidth 2% of center frequency.
HighCut: OUT, 250, 500 or 1000 Hz, 24 or 48 dB/octave.

LineTesting: Real time noise monitor displays real-time output from geophones. Optional geophone pulse test helps identify bad geophones and shorted or broken cables.

Data Storage: Stores data on local hard drive, local RAID, or NAS. Tape support available under Windows XP.

Triggering: Positive, negative or contact closure, software adjustable threshold.

Data Formats: SEG-2 standard with SGOS. SEG-D and SEG-Y available. 2

Power: Requires 12V external battery. Uses 0.65 W/channel during acquisition, sleep mode reduces power consumption by 70% while in standby.

Plotters: Drives most Windows-compatible printers and plotters

Environmental: -30 to 75 degrees C. Waterproof and submersible. Withstands a 1 m drop onto concrete on 6 sides and 8 corners.

Operating System: Windows XP/W2K/ME/98/NT/Vista. An older, limited feature version of the software is available for 95

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