Bison Instruments, Minneapolis, has announced model 2390, a deep-penetration earth resistivity system for locating and delineating ground-water aquifers, salinity contamination, pollution, rock, sand, or gravel and ore deposits.
A signal enhancement feature is said to give the 2390 increased sensitivity and accuracy as well as greater depth penetration than conventional systems. Small successive coded signals are electronically summed over a long time period to produce a more clearly readable signal with less power consumption. Voltage interference from natural earth currents is electronically canceled, allowing highly accurate studies for difficult applications requiring deep penetration. Other features include a liquid crystal digital readout that automatically displays the voltage value of the received signal.