Within the exploration community there is a well known trade-off between depth of exploration and target definition in terms of conductivity, extent and orientation. Greatest depth is obtained with large fixed loop Turam-type systems which generate large half-space responses that, along with current gathering, makes target detection difficult. Better spatial resolution is obtained with a moving transmitter configuration with a short intercoil spacing, but is limited to a shallower depth of exploration. These variations in survey requirements make system flexibility an important design consideration.

Time domain systems are also routinely employed for general geological applications, such as exploration for freshwater aquifers in bedrock fractures, and mapping groundwater contaminant plumes. Investigations to shallow depths, as necessary in these applications, requires a very wide bandwidth and many narrow sampling gates.

Recognition of such diverse requirements led to the development of the extremely flexible PROTEM time domain system. The digital, three component receiver is used with any of the three TEM transmitters and choice of receiver coils to cover all applications. With true 23 bit resolution (at a single gain), system bandwidth of 270 kHz, microsecond sampling gates and simultaneous three component (XYZ) measurements, the PROTEM receiver provides the ultimate in time domain capability.

The PROTEM receiver enables the selection of either 20 gates per base frequency covering two decades of time, or 30 gates for a three decade range. If three decades of time are required to cover the decay, then this selection saves switching frequencies and repeating the measurement; if only two decades are required, using the 20 gate range reduces the measurement time by a factor of 10.