Identification and High-Accuracy Range Estimation With Doppler Tags in Radar Applications

Radar sensors are widely used to support further system automation as they reliably provide range, velocity, and angle information for multiple objects. Nevertheless, unique identification of an object is not within the typical function range of radar; often, supportive systems are required. To overcome this limitation, a multipurpose tag concept for fast chirp frequency-modulated continuous wave (FC-FMCW) radar is introduced. The Doppler tag applies an artificial frequency shift following the Doppler phenomenon for unique identification of tagged objects with conventional radar hardware. It enables simultaneous detection and feature estimation of tagged and untagged objects. The idea of the Doppler tag is presented together with a realization and the required signal processing to allow for identification and high-accuracy range estimation. Simulations and measurements are provided to support the overall understanding and prove the functionality of the radar-tag system.