The combination of advanced radar sensor technology and smart grid has broad prospects. It is meaningful to monitor the respiration and heartbeat of grid employees under resting state through radar sensors to ensure that they are in a healthy working state. Ultra-wideband (UWB) radar sensor is suitable for this application because of its strong penetration ability, high range resolution and low average power consumption. However, due to weak heartbeat amplitude and measurement noise, the accurate measurement of the target heart rate is a challenge. In this paper, singular spectrum analysis (SSA) is proposed to reconstruct the eigenvalues of noisy vital signs to eliminate noise peaks around the heartbeat rate; combined with the variational modal decomposition (VMD), the target vital signs can be extracted with high accuracy. The experiment confirmed that the target vital sign information can be extracted with high accuracy from ten subjects at different distances, which can play an important role in short distance human detection and vital sign monitoring.

Due to the small size and various types of foreign object debris (FOD), radar detection of FOD on airport runways is a great challenge, and there are often a large number of false alarms in the detection results. Arc-scanning synthetic aperture radar (AS-SAR) is an emerging method for detecting FOD targets, which achieves omnidirectional coverage with a very high azimuth resolution. However, this method faces a similar challenge. A direct way to reduce false alarms is to increase the detection threshold based on enhancing the target signal-to-noise ratio (SNR), and in this paper, the coherent accumulation of multiple images is used to improve the target SNR. The stable phase is also an important feature of the target distinguishing background. Therefore, it is important to maintain the stability of the target phase. Aiming at the systematic phase drift (SPD) caused by atmospheric disturbance and system hardware, a spatial and temporal model is established, a corresponding correction approach is proposed, and the performance of the correction approach is validated by field experiments.

To improve the accuracy of radar ranging and positioning under complex backgrounds, a high-precision synchronization detection method for bistatic radar is proposed based on different-frequency phase processing. First, the transmit signal and receive signal are converted to radio frequency pulses by frequency conversion. Then, the transmit signal is roughly measured with a field-programmable gate array. The obtained rough signal is used as the reference signal under the control of the direct digital synthesizer frequency synthesizer. Second, the transmit signal and receive signal are each synchronized with the reference signal in a different-frequency phase detection. These detection results are used as the starting signal and stopping signal of the counter gate. Finally, all the signals are counted, and the time synchronization between the transmit signal and the receive signal is implemented by processing the counting value. The experimental results show that a time synchronization precision of 1.5 ps and a frequency stability of 6.2 × 10⁻¹³/s can be reached. This method has the advantages of a fast time response, good noise suppression, and high measurement precision and strong system reliability.

To meet the requirements of high-precision measurement of time-frequency multiparameters, a high-accuracy frequency standard comparison technology combining adaptive frequency and Lissajous figure is proposed. This technology uses only one reference frequency source to realize the frequency standard comparison and frequency measurement between any frequency signals without frequency normalization. First, a new frequency standard comparison signal is obtained by using an adaptive frequency standard generation module to roughly measure the measured frequency. Second, the turning period is measured by observing the Lissajous figure. Third, via the turning period and the function relation of frequency deviation, the relative frequency difference between the measured and frequency standard signals can be obtained. Finally, the phase relation between the measured and frequency standard signals is determined by oscilloscope, and then the high-accuracy measurement of the measured frequency can be realized. The testing results indicate that the accuracy of the frequency measurement in the radiofrequency range can achieve the $10^{-12}$ order of magnitude. Compared with the traditional frequency standard comparison technology, this technology has many characteristics, such as simple operation, low cost, low noise, and high measurement accuracy.