Design and implementation of a digital impulse generator for a 24GHz UWB radar

In this paper, we design and implement a digital impulse generator using a DCM block and an OSERDES block for a 24GHz UWB impulse-Doppler radar. The Federal Communications Commission (FCC) has confirmed the spectrum from 22 to 29GHz for UWB radar with a limit power of -41.3dBm/MHz. UWB signal possesses an absolute bandwidth larger than 500MHz or a relative bandwidth up to 20%. The vehicle radar is the key technology with the inherent advantage detected the distance and the velocity regardless of weather. Radar has a role to measure the distance and the velocity of long-distance vehicle. But, the radar with 1m resolution is difficult to satisfy the detection performance in the blind spot zone because the blind spot zone needs high resolution. So, UWB impulse-Doppler radar with 30cm resolution is suitable for the blind spot zone. The designed impulse generator has a 2ns pulse width and 100us PRI. We perform simulations through Xilinx ISE; experiments use a spectrum analyzer and a digital oscilloscope. For UWB radar, we use an AD9779 DAC module with a 1Gsps maximum sampling rate. For equipment, we use a TDS5104B oscilloscope of Tektronix with 3dB bandwidth at 1GHz for the analysis of the time domain and an E4448A spectrum analyzer of Agilent with a 50GHz spectrum for the analysis of the frequency domain. The results of the digital impulse measurement show a 2ns pulse width in the time domain, a 500MHz bandwidth, and a 10KHz spectrum peak in the frequency domain.