Specialized computing system for determining parameters of periodic radio signals based on wavelet analysis

The article considers practical issues of wavelet analysis application using the Morlet function in systems for measuring parameters of periodic signals. The use of direct conversion of input radio signals is becoming increasingly widespread, including in such areas as SDR. For efficient implementation of such a radio system, a computing platform is required that converts the input stream of digital samples. Digital signal convolution methods with a special kernel are used as conversion algorithms. Of interest are kernels belonging to the class of wavelet functions, but their application requires streaming execution of the "multiplication with accumulation" operation. The Morlet wavelet function known in the literature provides an optimal ratio of integration time and bandwidth, but does not allow the use of fast conversion algorithms similar to FFT. In addition, an increase in the order of the filter based on the Morlet wavelet leads to the need to implement a specialized computing system that can provide high computing performance, as well as storage or generation of digital samples that form the Morlet wavelet. In this paper, the structure of a digital sample generator based on CORDIC modules is considered. The use of a combination of harmonic and hyperbolic functions provides the creation of samples of the basic harmonic series and modulation by the Gaussian function, which ultimately yields the required Morlet wavelet. The applied pipeline architecture corresponds to modern approaches in the field of digital microcircuit synthesis, and allows, in particular, the creation of high-performance digital signal processing devices based on FPGA. The paper evaluates the logical capacity and performance characteristics of the meter when implemented on FPGA with 28 nm technology and better. The pipeline architecture of the computing device with switched operations at the pipeline stages is considered, which makes it possible to perform not only step-by-step calculations of the "multiplication with accumulation" type, but also a step of the algorithm for determining harmonic and hyperbolic functions, on the basis of which it becomes possible to generate samples of the Morlet wavelet function in real time. This architectural approach, which allows for the configuration of computing device functions during operation, is becoming increasingly relevant due to the constant growth of the cost of preparing the production of electronic component base. Increasing the order of the convolution kernel allows for improving the metrological characteristics of the digital device being developed for processing periodic radio signals.