(n.) Formation Evaluation. A resistivity recorded by a measurements-while-drilling propagation tool consisting of an array of transmitters and receivers whose signals are recorded separately and combined by software to produce the response desired. In a typical design, five transmitters emit a signal, and the phase shift and attenuation between two receivers are recorded. The phase shifts and attenuations are combined in different ways to produce borehole-compensated logs with different depths of investigation and radial resolution. See: Borehole Compensation, Propagation Resistivity, Propagation Resistivity Measurement, Resistivity Log. More Details: Resistivity While Drilling: Images from the String