Figure 4
From: Remote sensing of soil moisture using Rydberg atoms and satellite signals of opportunity
An emulated XM signal (2 MHz bandwidth QPSK signal with random bitstream) is used as a transmitter to study sensitivity of Rydberg atomic detectors to soil moisture (SM). (a) The transmitter is driven by a vector signal generator. (b) A soil sample (sand, fine particle size < 0.42 mm) is used in a sample container of 1.5 × 2 × 1.5 ft. MW absorber foam is placed outside the specular region to attenuate reflections of the container and ground. An in-situ SM probe is used to obtain ground truth measurements. (c) Radar scattering coefficients sensed by the Rydberg atomic readout (top) and error is SM (bottom) inversion as a function of volumetric SM content, showing < 0.5% error in SM inversion (see Methods for details).
