Abstract: An NMR locking mechanism for use with not only electromagnets, superconducting magnets and permanent magnets, but also with ultrahigh energy product magnets such as neodynium. The circuit utilizes a single conversion superheterodyne receiver with a phase locked loop that forms a locking mechanism that depends upon a variable frequency. The resonant frequency of the nuclei is compared to a variable excitation frequency which is adjusted to maintain a control frequency with one unique value of the control frequency being zero at lock.

Abstract: A true logarithmic amplifier is used in combination with an apparatus for transmitting and receiving signals produced during nuclear magnetic resonance analysis. The true logarithmic amplifier is used to compress the dynamic range of signals produced by the reorientation of excited magnetic dipoles such as those of protons as they return to an aligned, unexcited state, with the compression of the dynamic range avoiding saturation of the amplifier by strong signals and preserving all phase information and hence sideband components of the received signals for processing and analysis.