Frequency Stepped Chirp Radar: Simulating and Testing Signal Processing Methods

Mr. Frank Raffaeli, Principal RF/microwave Engineer, NI and Trang D. Nguyen, Master Project Manager, NI

Date: Issue 63 - September 2015

Today’s radar systems not only serve applications areas of defense, weather and law enforcement but, radar technology is utilized in automotive and public transportation safety features, global mapping, oil exploration and even quality control for manufacturing methods requiring surface precision or material integrity. A variety of radar techniques have emerged to support this broad range of application areas. However, the fundamental ability of a radar system to process reflected radio frequency (RF) information and to identify the parameters of location, speed and direction of an object remains the primary and most utilized function of modern radar. 

Most radar systems use a pulsed microwave signal directed toward the object of interest, to collect the reflected energy via the same transmitting antenna. However, some systems achieve this measurement by using Frequency-Stepped Chirped Radar (FSCR) signals to transmit pulsed, linear frequency ramps (also known as chirps). The FSCR radar is distinguished by its ability to achieve a high range resolution in a system that has limited instantaneous bandwidth. Successive pulses increase linearly in discrete steps. The pulse modulated signal is transmitted using an antenna. The echo signal reflected back is combined with the transmitted signal to create a beat signal to calculate the round trip time, which is inversely proportional to the bandwidth (BW). Range resolution is the ability to distinguish between two different targets at the same bearing with two different ranges [Pourvoyeur, et al.].