Radio-frequency signal synthesis and digital signal processing technique for software defined radar system

This work presents a complete hardware and standalone implementation of a cost-effective software-defined radar system based on the architecture proposed during the thesis work of Hui Zhang, a former Ph.D. student. One objective of this implementation is to realize the planarization and miniaturization of such a radar system by deploying the substrate integrated waveguide (SIW) technology.;Echoed by the target, the EMW are received by two receiving antennas and then they are sent to a receiver front-end. According to the use of Doppler Effect, the speed measurement is accomplished by using the CW waveform while the range is measured by the FMCW waveform. Moreover, the presented radar system yields the angle measured by using a phase difference between the two receiving channels.;The subsystem following the receiver is the digital signal processing unit with an analog digital converter (ADC) as the interface between the analog and the digital parts. The ADC samples the analog signal with a rate of 80 kHz and a resolution of 8 bit. Then FFT calculations are carried out to generate the waveform data from both channels and, the frequency information about the target is found from which the speed, range and angle information of the target can be obtained.;The entire radar system integrated with the SIW technique is completely realized and verified. The presented system has successfully demonstrated the design and application of cost-effective planar radar.;The requirement of software-defined radar systems is to measure the speed, range and angle of a target by an integrated planar circuit platform. In order to satisfy this requirement, this developed software-defined radar system combines two functions, namely, frequency modulated continuous wave (FMCW) and continuous wave (CW), and the switching between them is controlled by software running in a micro-processor. In our implementation, the frequency synthesizer is configured by a direct digital synthesizer (DDS) which can flexibly generate various signals such as CW and FMCW. In addition, a phase-locked loop (PLL) is used to up-convert the signal from DDS to an upper frequency platform. Subsequently, the generated high frequency signal is transmitted by a power amplifier and radiated by an SIW antenna. Electromagnetic waves (EMW) are radiated in a narrow angle range thanks to attractive characteristics of the SIW antenna such as high gain, small size, and planar implementation.