A Simplified Technique for Distance and Velocity Measurements of Multiple Moving Objects Using a Linear Frequency Modulated Signal

In this paper, we propose a simplified algorithm for the unbiased estimation of range and the radial velocity of moving objects observed by a sensor with a frequency-modulated continuous wave signal. Linear frequency modulated signals and their different modifications are widely used in various microwave sensors for short- to medium-range measurements in automotive, safety, industrial, and other applications. Since the range (distance) to a detected object is measured as a beat frequency at the homodyne receiver output, the Doppler shift results in a biased measurement of the range. This phenomenon has been well known for a long time. The situation becomes more uncertain with an increase in the number of objects within the radar's field of view. There are many proposed techniques to solve this problem with one main technique adding a number of equations according to the number of detected objects in the hope of finding a single solution. We propose a simplifed system of those equations excluding all uncertainties from the hypothesis tree at the beginning of the procedure. When the performance of the signal processing hardware is limited, the simplicity of the algorithm increases in importance. The proposed technique is simple enough to be used on an embedded microprocessor. We performed an experiment involving a real microwave sensor to confirm a validity of the proposed algorithm.