Identification of FMCW radar in mutual interference environments using frequency ramp modulation

This paper proposes a scheme to avoid mutual interference in frequency-modulated continuous-wave (FMCW) radar through the modulation of the frequency ramp with time. When multiple FMCW radars are being used simultaneously, the detection of beat frequency can be erroneous because the transmitted signals from other radars mutually interfere with the original signal. To detect the beat frequency of particular radar, we impose an orthogonal pattern in the change of frequency ramp slope. A single burst of FMCW radar comprises hundreds of frequency sweeps, and the slope of frequency ramp is modulated in a predefined matter. Then each radar has its own unique pattern in a spectrogram for a target; therefore the target range can be determined by observing the correlations between the obtained beat frequency spectrogram and a pattern simulated depending on distance. In this study, a sinusoidal pattern is employed to obtain orthogonality between radars. The simulation result shows that a target of interest could be successfully detected in an environment with mutual interference.