NLFMNewfoundland and Labrador Federation of Municipalities (Canada)
NLFMNon-Linear Fracture Mechanics
NLFMNon-Linear Frequency Modulation
NLFMNoise Level Monitor Sonar (US Navy)
NLFMNoise Level Frequency Monitor
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According to [3], beside of other well-known methods (e.g., explicit functions cluster method etc.), the stationary phase principle-based technique is one of the most important synthesis tool of the complex modulated radar signals (e.g., NLFM signals) with a predefined shape of the PSD function.
In addition, by this method, some major disadvantages assigned to the standard weighted filtering can be also removed etc.), to achieve the synthesis of proper signal (e.g., NLFM) waveforms.
In order to obtain the structure of the proposed NLFM synthesis algorithm, some working hypothesis will be made, namely:
Finally, in order to have a complete view of NLFM signal synthesis process based on stationary phase method, it is interesting to analyse the influence of the Doppler frequency shift F on the shape assigned to the normalized complex envelope of the signal autocorrelation function.
In addition, by suitable numerical methods, the temporal samples of NLFM signal phase are thus obtained.
Having as starting point the experimental results reported in [13-15], it seems that some very good results have been obtained in case of Taylor and Blackman-Harris weighting windows as sidelobes reduction techniques, and therefore, these two types of PSD functions will be next used for synthesis and comparative analysis of the matched NLFM laws by the above described algorithm.
Synthesis and Analysis of the NLFM Signal Using a Taylor PSD Function
Synthesis and Analysis of the NLFM Signal Using a Blackman-Harris PSD Function
Finally, it is interesting to present a synthetic analysis of NLFM radio pulse based on ambiguity function tool use.
The theoretical and experimental results presented in this paper lead to the following important remarks related to the synthesis of some NLFM laws by stationary phase method as sidelobes suppression technique, namely:
c1) having as a starting point the remark that the level assigned to the signal sidelobes is determined by the shape of the spectral density function and also imposing a certain pattern to its module, a powerful synthesis algorithm by stationary phase method of a proper NLFM radio pulse which assures a level of the sidelobes of the autocorrelation function less than -40 dB and preserves the (LFM) range resolution, was theoretical discussed;