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The frequency domain signal is the result of applying the FFT to one ramp modulation interval of the 2048 sampled IF radar signal captured samples.<br>
You can see the spectrum of the radar IF signal in real time thanks to the power of the OMAP processor, by clicking on the "F(jw)" icon:
[[Image:WEB_HOME_PAGE_FWEB HOME PAGE F(jw)_NEWNEW.jpg]]
The radar application takes the samples of a single ramp and, if needed, it completes the rest with zeros (padding), thus completing the 2048 samples. Then it performs the FFT over these 2048 samples, resulting on the spectrum of the signal with 2048 points resolution:
<br> [[Image:FFT_2m_FFT 2m -T_600_NEWsT 600 NEWs.jpg]]<br>
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Following our example, the above picture shows the FFT of the measurement. Y axis represents signal strenght and X axis represents the FFT sample. Note that only the 500 first samples are shown.
We can see a dominant peak centered about sample number 16. This peak should correspond to the measured dominant sinus of 45,609KHz 760KHz on time domain graphic.<br>
The sampling rate used by the equipment with the default modulation is 590Ksps. This means that each sample of the FFT represents 590000/2047=288,2Hz.
If the peak is centered about sample 16 20 it means the frequency represented is 1620*288,2Hz=45,611KHz764KHz, thus corresponding with accuracy with the calculations made on time domain.
We can see other small peaks at about samples 40 and 50. These peaks are due to other reflections on the room at a longer distance. So here an example of the possibilities of the radar to detect several targets at different distances. But by the moment is better if we pay our attention on a single target scenario to keep learning about the radar signal and later we will be able to analyse more complex scenarios.
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