Speed Calibration and Traceability for Train-Borne 24 GHz Continuous-Wave Doppler Radar Sensor

Area of Science:

• Electrical Engineering
• Transportation Technology
• Metrology

Background:

• 24 GHz continuous-wave (CW) Doppler radar sensors (DRS) are crucial for non-contact speed measurement.
• Train-borne DRS are increasingly used in China for advanced performance in speed measurements.
• Existing calibration methods for train-borne DRS have limitations.

Purpose of the Study:

• To introduce the architecture and working principles of various train-borne DRS.
• To propose a novel speed calibration method for train-borne DRS using Doppler shift signal simulation.
• To develop and validate a simulation system for calibrating train-borne DRS.

Main Methods:

• Detailed introduction of single-channel and dual-channel train-borne DRS architectures.
• Development of a new calibration method by simulating Doppler shift signals via incident CW microwave signal modulation.
• Realization of a 24 GHz CW radar target simulation system for train-borne DRS verification.

Main Results:

• The simulation system covers a speed range of 5–500 km/h with an incident angle of (45 ± 8)°.
• The maximum permissible error (MPE) for simulated speed was ±0.05 km/h.
• Calibration and uncertainty evaluation of dual-channel DRS samples confirmed the method's effectiveness and feasibility.

Conclusions:

• The proposed Doppler shift signal simulation method offers an effective and feasible approach for calibrating train-borne DRS.
• The developed simulation system accurately validates the calibration method across a wide speed range.
• This advancement enhances the reliability and precision of train speed measurements in both laboratory and field settings.