Elrec Terra
from Iris Instruments

The Elrec Terra is the new improved 20ch Induced Polarisation (IP) and resistivity receiver, designed with a new color touch screen to display the IP decay curves alongside the resistivity pseudosections in detail. With this modern re-design the user can easily navigate through the system menus and mark/ type many of the survey parameters without solely using the touch pad. A compact and robust receiver which can be used in a wide variety of field environments, as it has a large temperature range between -20°C to 60°C; with its 20 channels and 24bit converter (31 bits of dynamic range (at 100Hz) the system can measure very small IP signals. Whilst measuring IP and Res data, the unit records fullwaveform 20ch voltage timeseries data in the background which can later be post-processed in Full wave viewer (free to use software). The acquired data is stored with one sample every 10ms (full decay curve). In terms of position, the Elrec Terra has an internal GPS and automatic handle of local and global coordinates, which helps the user to spatially visualize the data on google earth.

Similar to the Syscal systems, the Elrec Terra is available in standard or switch mode (48 to 120 electrodes) and the standard Electre pro can be used together with a number of switch terra systems for a larger configuration (e.g. Connect two Electre terra switch in master-slave mode to > n.o electrodes 48ch becomes a 96ch system) increasing the system scalability (Fig. 1). If required, the system has a built-in test function which with the provided test equipment, can be used to check the system whilst in the field, allowing more efficient use. Any datafiles can be downloaded onto a USB drive or via WIFI connection to a smartphone or tablet, if shipping the unit, the LI batteries can be removed for ease of transport.

The system has a one-time acquisition mode when used together with the TIP6000 transmitter which reduces the measurement time by a factor of two and doubling > the IP signal strength. By reducing the time the user can enhance the data quality and improve productivity. As standard, during the current 50% duty cycle the IP is normally measured in the off time period but this technology utilises measuring the IP in the on time period (100% duty current cycle) dividing the total measurement time by two and multiplying the electric potential by two, the TIP (6kW or 12kW) is the only system which allows good current stability of the injected current, enabling this type of measurement.