Improvement of the Performance of FM-CW Radar Systems by using Direct Digital Synthesizers: Comparison with Voltage Controlled Oscillators

Abstract

linear frequency modulated continuous wave (LFM-CW) radars require high linearity and good phase noise characteristics of its modulated signal to obtain a good resolution and sensitivity. Direct digital Synthesis (DDS) is becoming an increasingly competitive alternative to traditional Voltage Controlled Oscillators (VCO) to perform the modulation. Although there are plenty of publications describing the performance of the DDS, there has up to now not been any direct comparison between the performance of the DDS and the VCO as applied in FM-CW radars. In this paper the performance of DDS is analyzed both theoretically and with measurements. The performance of DDS in a linear frequency modulated continuous wave (LFM-CW) radar system, (the Transportable Atmospheric Radar TARA developed in IRCTR), is compared to a VCO demonstrating its superiority. DDS is, therefore, expected to play an important role in radar systems in the near future.