The disclosure provides a radar apparatus fur estimating a distance of the one or more obstacles in a range of interest. The radar apparatus includes a local oscillator that generates a first ramp segment having a first start frequency. A frequency shifter receives the first ramp segment and generates a transmit signal and a mixer signal. The transmit signal is scattered by a one or more obstacles in the range of interest to generate the scattered signal. A mixer mixes the scattered signal and the mixer signal to generate a non-zero IF signal which is filtered to generate a filtered non-zero IF signal. An ADC (analog to digital converter) samples the filtered non-zero IF signal to generate a valid data. A DSP (digital signal processor) processes the valid data for estimating the distance of the one or more obstacles.