The absolute-distance measurement results for a human being show that the vital signs obtained at each frequency using the proposed FSK radar have a cross-correlation. The phase difference between transmitted and received signals at each frequency is determined after calibrating the I / Q imbalance and direct-current offset using a data-based imbalance compensation algorithm, the Gram-Schmidt procedure, and the Pratt method.
#DC DOPPLER RADAR GENERATOR#
Two frequencies-2.45 and 2.5 GHz-are effectively discriminated by using the envelope detection with the frequency control signal of the signal generator in the output waveform of the FSK radar. The measurement accuracy of the proposed detector for the heartbeat is increased by using the cross-correlation between the phase differences of signals at two frequencies used by the FSK radar, which alternately transmits and receives the signals with different frequencies. The study indicated high accuracy in classifying different types ofĪ frequency-shift keying (FSK) radar in the 2.45-GHz band is proposed for highly accurate vital-signs detection. The machine learning/ deep learning models based on the collected data wereĭeveloped. The radar sensing system to develop the smart microwave radar sensing system. Artificial intelligence was then integrated with This system showed an enhancement in the accuracy and directional signals of Further investigation into the theoretical models, proposedĪ novel system that was inspired by the microbat animal’s physical structure. These models are very useful for hardware development of microwave radar sensors. System were then developed and validated to examine the accuracy of the system Models to evaluate the false alarm/detection probabilities of a microwave sensing The antennae system had an extremely large band width,
In this research, the antennae systems for vital signs detection, such asīreathing rate, were first investigated to validate their performance in a system atĭifferent frequencies. The present study has focused on microwave sensors, studying microwave theoretical models and searching for life detecting, health care and smart home applications. In general, the digital-IF Doppler radar has three layers: the RF layer, the digital-IF layer and the baseband layer.
10.1 Principles of digital-IF Doppler radar Figure 10.1 shows the simplified block diagram of a CW Doppler radar with digital-IF architecture. non-contact beat-to-beat blood pressure (BP) estimation and multi-sensor-based sleep-stage classification, are briefly introduced. After the introduction of radar sensor, two applications, i.e. The digital-IF Doppler radar can not only work as a single sensor but also serve as a sensor in the multi-sensor network. Recently, developed from the conventional application of vital sign detection, the digital-IF Doppler radar is widely applied for healthcare sensing. Then, the radio frequency (RF) layer, IF layer and optimised baseband signal processing are discussed. In this chapter, the principle of the digital-IF Doppler radar is introduced. Fortunately, the digital receiver with direct intermediate-frequency (IF)-to-digital conversion (IF sampling) is a suitable alternative. However, it encounters several problems such as quadrature channel imbalance and DC offset.
The homodyne CW Doppler radar is widely used due to its simple structure and low cost. Various types of radar sensors have been developed for non-contact vital sign detection including single-carrier continuous-wave (CW) Doppler radar, frequency-modulated CW radar, stepped frequency CW radar and ultra-wideband radar. The vital sign-induced micro-Doppler effect, which is also called vital Doppler, has been widely used for radar-based non-contact vital sign detection. breathing and heartbeat) and non-periodic body movement cause the micro-Doppler effect. Compared with walking and running, the periodic body movement (i.e. According to the definition of the Doppler effect, walking and running can generate the frequency shift when the human target is moving forth or back with respect to the radar sensor.
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