DDS Based Low Phase Noise LFM Generator for Multi Object Tracking Radar

Direct Digital Synthesizer (DDS) based L-Band Linear Frequency Modulation (LFM) Generator is used as the transmitter in Multi Object Tracking Radar to identify and track multiple targets. Its applications include tracking of launch vehicles and remote sensing satellites for orbit prediction as well as space debris tracking in Low Earth Orbit (LEO). Pulse compression of LFM signal is used to improve range resolution of the radar, without compromising its range. Since LFM generation by Phase Locked Loop (PLL) method has disadvantages like instability and nonlinearity, a different technique of generating IF modulated signal with DDS, followed by up-conversion is proposed. The system generates a chirp signal having center frequency tunable from 1.3GHz to 1.4GHz, with dynamically configurable chirp direction, pulse width and chirp bandwidth. The synergistic combination of latest high speed digital, mixed signal and RF ICs helped in achieving a low phase noise of −90dBc/Hz at 100Hz offset, which is required for high range accuracy and for tracking slow moving targets.