Patent ID: 8847816
Filing Date: 2014-09-30
Classification: G01F,G01S

Abstract:
1. A method for lessening disturbances of a measurement signal in a radar unit for distance measurement by means of frequency modulated radar in continuous wave operation, comprising the steps of: registering in a reference measurement a reference signal as a function of time; deriving an error correction signal from the registered reference signal, wherein the error correction signal predominantly comprises spectral components, which are caused or influenced by device-specific defects of the radar unit; registering a measurement signal; and correcting the measurement signal in accordance with the error correction signal by means of digital signal processing, wherein: the method is applied for lessening close-range disturbance signal fractions; the error correction signal has close-range disturbance signal fractions but no target frequency components; the corrected measurement signal with a lessened part of close-range disturbance signal fractions is produced by subtraction of the error correction signal from the measurement signal; and at least one of the following features are included: the reference signal is filtered by means of a zero phase, low-pass filter; the reference signal is filtered by means of a digital IIR filter with unlimited pulse response; the error correction signal is produced from the reference signal by first a forward filtering and then a backward filtering of the registered reference signal; and before performing a digital filtering, registered digital sample values of the reference signal are supplemented by other sample values by means of autoregressive extrapolation.