Performance analysis of radar digital signal processing

In pulse radar, digital signal processing can be divided into two parts: intra-cycle processing and inter-cycle processing. Intra-cycle processing refers to matching or optimal filtering of echo pulses in a cycle to maximize the signal-to-noise ratio of a single pulse; Interval processing refers to the matching or optimal filtering of the complex envelope of the echo pulse train in multiple periods, so as to maximize the signal-to-noise ratio at a certain time in the whole pulse train. For intra-period processing, the sampling period should be less than or equal to the resolution unit used to measure the time delay (distance). For interval processing, the sampling period can be as long as one repetition period.

Digital signal processing can be divided into four categories, namely, linear time-invariant, linear time-varying, nonlinear time-invariant and nonlinear time-varying. Theoretically, the simplest solution is to deal with linear time-invariant variables. This kind of analog processing is described by linear constant coefficient differential equations, so it can be solved by Fourier series or Fourier transform. Similarly, this type of digital processing can be described by a linear difference equation with constant coefficients, which can be solved by Z transform or discrete Fourier transform.

It is effective to solve the analysis problem of linear time-varying digital processing with state variable method. This method is especially suitable for analog analysis with electronic computer. With regard to the nonlinear digital processing, only computer simulation calculation can be carried out for specific problems, and the superposition principle cannot be applied.