From this paper, it can be seen that different waveform length have different Debye length effects. The real incoherent scattering requests that the operating wavelength (λ) of radar must be far less than the Debye length (λD) of plasma, while the operating wavelength (λ) we detect in actually is longer than or far longer the λD. This paper introduces the design concept of a low cost, low power software defined ISR system, SDISR, which can continuously probe the real time plasma parameters in the