## Zoom FFT - MATLAB & Simulink

Understanding FFTs and Windowing Overview Learn about the time and frequency domain, fast Fourier transforms (FFTs), and windowing as well as how you can use them to improve your understanding of a signal. This tutorial is part of the Instrument Fundamentals series. Contents wwUnderstanding the Time Domain, Frequency Domain, and FFT a. This example showcases zoom FFT, which is a signal processing technique used to analyze a portion of a spectrum at high resolution. DSP System Toolbox offers this functionality in MATLAB through the ushealthlife.mlT System object, and in Simulink through the zoom FFT library block. The Zoom FFT is interesting because it blends complex down conversion, lowpass filtering, and sample rate change through decimation in a spectrum analysis application. The Zoom FFT method of spectrum analysis is used when fine spectral resolution is needed within a small portion of a signal’s.

Richard Lyons. Richard LyonsFebruary 22, The Zoom FFT is interesting because it blends complex down conversion, lowpass filtering, and sample rate change through decimation in a spectrum analysis application. This technique is more efficient than the traditional FFT in such a situation. Think of the spectral analysis situation where we require fine frequency resolution, closely spaced FFT bins, over the frequency range occupied by the signal of interest shown in Figure 13—52 a below.

The other signals are of no interest to us. Figure 13— Zoom FFT spectra: a input spectrum; b processing scheme; c downconverted spectrum; d filtered and decimated spectrum. We could collect many time samples and perform a large-size applications of zoom fft FFT to satisfy our fine spectral resolution requirement, applications of zoom fft. The Zoom FFT can help us improve our computational efficiency through:.

The Zoom FFT technique requires narrowband filtering and decimation in order to reduce the number of time samples prior to the final FFT, as shown in Figure 13—52 b. Unlike the case of real inputs, where the positive and negative frequency ranges are redundant. The implementation of the Zoom FFT is given in Figure 13—53 belowwhere all discrete sequences are real valued.

Figure 13—53 Zoom FFT processing details. Relating the discrete sequences in Figure 13—52 b and Figure 13—53, the complex time sequence xc n is represented mathematically as:. Plotting Eq.

We see that the Zoom FFT affords significant computational saving over a straightforward FFT for spectrum analysis of a narrowband portion of some X m spectrum - and the computational savings in complex multiplies improves as the decimation factor D increases.

You may be able to use a simple, efficient, IIR filter if spectral phase is unimportant. If phase distortion is unacceptable, then efficient polyphase and half-band FIR filters are applicable, applications of zoom fft. Computationally efficient frequency sampling and interpolated FIR filters should be considered.

If the signal of interest is very narrowband relative to the fs 1 sample rate, requiring a large decimation factor and very narrowband computationally expensive filters, perhaps a cascaded integrator-comb CIC filter can be used to reduce the filtering computational workload. Used with the permission of the publisher, Prentice Hall, this on-going series of articles on Embedded. The book can be purchased on line, applications of zoom fft. Richard Lyons is a consulting systems engineer and lecturer with Besser Associates. Understanding FFTs and Windowing Overview Learn about the time and frequency domain, fast Fourier transforms (FFTs), and windowing as well as how you can use them to improve your understanding of a signal. This tutorial is part of the Instrument Fundamentals series. Contents wwUnderstanding the Time Domain, Frequency Domain, and FFT a. Section 6 shows applications of differ-ent approaches in radar signal processing for estimation of preted as a zoom-FFT similar to the zoom-FFT method 1 to find the band of interest with a high resolution. In Fig. 1 a(n) and b(n) are the low-pass and high-pass. Dec 21,  · I know one application is large integer multiplication. Since a number n in base b can be represented by a series of coefficients {N}={n_k, n_(k-1), n_0} is equivalent to the polynomial p(x)=n_k*x^k+n_(k-1)*x^(k-1) +n_0*x^0 evaluated at x=b.