If the only need is to have a loop-powered sensor for monitoring the overall vibration, then sensors like the Wilcoxon 4-20 mA LPS® series will suffice. However, if very low or very high frequency monitoring is desired, the iT Transmitter series is necessary because they have the wide frequency response required. Also, a transmitter is required when it is desired to trend vibration in a limited portion of the frequency spectrum, but have the full spectrum available for detailed FFT analysis.