Before revision: SMOS Operating Principles It picks up thermal radiation emitted by the Earth near 1.4 GHz in the microwave L-band, amplifies it 100 dB, and digitises it with 1-bit quantisation.
After revision: Operating Principles SMOS Mission, ICM-CSIC (Spanish Institute of Marine Sciences – Spanish National Research Council), updated July 2008 It picks up thermal radiation emitted by the Earth near 1.4 GHz in the microwave L-band, amplifies it 100 dB, and digitises it with 1-bit quantisation.