Monday, January 20, 2020

FMCW (Frequency Modulated Continuous Wave) Open Air Radar Level Measurement

Non-contact level measurement using radar transmitters for the continuous, contactless level measurement of liquids, pastes, granulates, powders and other solids in a wide variety of industries.

Frequency Modulated Continuous Wave

  • The radar principle used is FMCW (Frequency Modulated Continuous Wave). The FMCW radar emits a high frequency signal whose frequency increases linearly during the measurement phase (called the frequency sweep). 
  • The signal is emitted via an antenna, reflected off the product surface and received with a time delay, t. 
  • Time delay, t=2d/c, where d is the distance to the product surface and c is the speed of light in the gas above the product. 
  • For further signal processing the difference Δf is calculated from the actual transmitted frequency and the received frequency. 
  • The difference is directly proportional to the distance.
  • A large frequency difference corresponds to a large distance and vice versa. 
  • The frequency difference f is transformed via a Fast Fourier Transformation (FFT) into a frequency spectrum and then the distance is calculated from the spectrum.
  • The level results from the difference between the tank height and the measured distance.

For additional information, call Piping Specialties, PSI Controls at 800-223-1468 or visit their web site at