Simulation and Performance Evaluation of Three Types of ISR Coding Systems

Incoherent scatter radar can measure a variety of ionospheric plasma parameters, but the associated radar echo signals are very weak. To extract the effective ionospheric parameters, complex coding schemes are used with modern incoherent scatter measurements. Long pulse code, Barker code, alternating code, and alternating code modulated by Barker code (i.e., composite code) are some of the more frequently used coding systems. In practice, ionospheric signals are easily disturbed by external factors, and thus, the echo signals contain substantial amounts of noise. Therefore, it is important to investigate the antinoise performances of these codes. According to the basic theory of the ambiguity function, simulations of the 2-D ambiguity functions of these four codes were conducted. In addition, waveform processing simulations were performed for the four codes. According to this letter, the composite code exhibits a greater range of detection, a higher range resolution, and better antinoise performance than the other three types of codes and is more conducive to the detection of weak signals.