FMCW RADAR IN THE DIGITAL AGE

Frequency modulated continuous wave (FMCW) radar, optionally with Doppler capability, is applied in atmospheric remote sensing since decades. The method is well understood and documented in its original theoretical analogue representation, as are its inherent restrictions. But since the introduction of the method the digitization has reached many areas of remote sensing. This started with digital data acquisition and signal processing, followed by digital signal pre-processing, and eventually has reached full digital generation of the transmitted signal or major components of this. This article aims to present an overview over the analogue method of FMCW (Doppler) radar and its inherent restrictions, and then extend this to the specifics and additional restrictions invented by digital data acquisition and signal processing and digital generation of the transmitted signal. The consequences of digital signal pre- processing will not be regarded in this article. An example for a digitally generated frequency sweep and how the signal quality can be measured concludes this contribution.