DDS-based intelligent modulation of the radio frequency field of helium optically pumped magnetometers

Geomagnetic field surveys have been widely applied in the fields such as basic geological study, mineral resource exploration, and military detection. A key tool for geomagnetic field surveys is helium optically pumped magnetometer probes. The frequency modulation precision of the radio frequency field used in the probes is an important factor affecting geomagnetic survey precision. To achieve frequency modulation signals featuring easy modulation, high precision, and high reliability, this study proposed an intelligent frequency modulation technology for the radio frequency field of the magnetometer probes by combining the direct digital frequency synthesizer (DDS) and the microcontroller unit (MCU). This technology can achieve flexible, real-time, automatic, and precise frequency modulation of the radio frequency field of the magnetometer probes. As revealed by the integration tests in which frequency modulation signals were loaded into the helium optically pumped magnetometer system, the magnetometer can obtain stable and precise magnetic resonance signals, thus ensuring high-precision geomagnetic field surveys.