SYSCAL Jr Switch-72 is a new all-in-one multinode resistivity imaging system. It features an internal switching board for 72 electrodes and an internal 100 W power source. The output current is automatically adjusted (automatic ranging) to optimise the input voltage values and ensure the best measurement quality. The system is designed to automatically perform pre-defined sets of resistivity measurements with roll-along capability. Four strings of cable with 18 electrode take-out each are connected on the back of the resistivity meter. Made of heavy duty seismic cable, these strings are available with standard 5 or 10 m electrode spacings. Customized cables may also assembled for special arrays or non-standard applications.

Compact, easy-to-use and field proof, the SYSCAL Jr Switch-72 measures both resistivity and chargeability (IP). It is ideal for environmental and civil engineering applications such as pollution monitoring and mapping, salinity control, depth-to-rock determination and weathered bedrock mapping. It can also be used for shallow groundwater exploration (depth and thickness of aquifers).

With the SYSCAL Jr Switch-72 resistivity surveys can be performed very efficiently with one operator only.

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RESISTIVITY IMAGING

Aim: imaging the underground geological structures through surface electrical measurements
Principle: transmitting a current I through two electrodes and measuring a voltage V with two other electrodes
Apparent resistivity: p = K*V/I, K depending on the electrode separation
Resistivity pseudo-section: contoured plot of the apparent resistivity data, using the electrode distance as a pseudo-depth parameter
True resistivity section: contoured plot of the resistivity distribution obtained through the inversion of the measured data (using a non linear parameter fitting scheme)
Applications: environmental studies, groundwater investigation, civil engineering, archaeology...

FIELD LAY-OUT

Preset arrays (Wenner, dipole,…) or customized arrays are uploaded through the user-friendly ELECTRE (version 2) PC software. The roll-along capability is implemented.

ACCURACY

Automatic SP compensation including linear drift
Digital stacking for noise reduction
Standard deviation computation
Noise may be monitored before injection

DATA INTERPRETATION SOFTWARE

RES2DINV or RESIX-2DI (PC), for pseudo-section inversion to true resistivity (and IP) 2D section.
RES3DINV (PC), for inversion to true resistivity (and IP) 3D data

OUTPUT CURRENT SPECIFICATIONS

Automatic ranging (microprocessor controlled)
Intensity: up to 1200 mA
Voltage: up to 400V (800V peak to peak)
Power: up to 100 W
Selectable cycle time of 0.5 , 1 or 2 s, programmable from 0.25 to 10 sec.
Current measurement precision: 0,5% typical.

INPUT VOLTAGE SPECIFICATIONS

Measuring process: automatic ranging and calibration
Input impedance : 20 MW minimum.
Input voltage protection up to 1000V, range from –5 V to +5 V.
Power line rejection
Voltage measurement precision: 0.5% typical
Noise reduction: continuous stacking selectable from 1 to 255 stacks.
SP compensation through automatic linear drift correction.
Resistivity accuracy: 0,5% typical
Induced polarization (chargeability) measured over four predefined windows.
Chargeability accuracy: 1% of measured value for input voltage higher than 10 mV.

GENERAL SPECIFICATIONS

Weather proof
Shock resistant fiber-glass case
Operating temperature: -20 to +70 °C
Dimensions: 31 x 23 x 35 cm. Weight: 11.5 kg
Internal memory for 2700 readings
Power supply: two internal rechargeable 12V, 7 Ah battery ; optional external 12V backup car battery for transmitter power
Autonomy with internal battery: several thousands of readings
18 take-outs cable string weight: 15 kg each for 5m spacing