By studying the discrete Fourier transform properties of the band-limited digital signal

the authors introduce alternating projection neural networks into the paper

expand APNN's application scope from real field to complex field

and present several important conclusions on APNN.Analyzing and discussing network's tolerance to noise

convergence rate and the spectral leakage problem of the truncated signal expected to be extrapolated by using these conclusions

the paper presents an extrapolation algorithm for band-limited signals based on alternating projection neural networks.A lot of simulation experiments show that the algorithm is effective.In addition

the algorithm is also effective to spectrum extrapolation.Owing to adopting network structure

the algorithm is prone to parallel computation and VLSI design

and consequently can satisfy real time military processing needs.