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''' 4.1.1 Sirad EvalKit '''
This section describes the measurement flow of the SiRad Evaluation Kit with its parameters. The measurement parameters as well as the kind and amount of transmitted data can be adapted using the SiRad Evaluation Kit communication protocol described in the following sections.
The signal flow of the radar measurement is shown in Figure 1. Each measurement cycle is initiated by either an internal ‘Self-Trigger’ (int) or an external ‘Manual Trigger’ (ext). Continuous measurements can be triggered with a certain trigger frequency (freq). </br>
Once a trigger is received, the PLL is started that drives a frequency ramp from fBase to (fBase + BW) with the currently set base-frequency (fBase) and the currently set bandwidth (BW). The radar frontend starts its detection in the chosen frequency range. </br>
The AD converter (ADC) begins processing the chosen number of data samples (nSmp) with a certain sample frequency (fSmp). The received data is amplified either by a manually set gain value (once) or by a continuously recalculated automatically acquired gain value (cont.), further named Auto Gain Control (AGC) Mode. If set, a DC cancellation is done.
The current measurement is repeated n times (for a number of nRamps frequency ramps) and the previous ramp is processed while a new ramp is generating. Therefore, depending on the processing settings, there can be a small delay between each ramp in one set. When downsampling is active (with a certain downsampling number nDown), each nDown ramps are summed and the rest is zero-padded. </br> The downsampled data is processed by a window function and then transformed by an FFT with nFFT points. The magnitude, phase and other information is extracted from the FFT output for the target list. The targets are detected by the CFAR operator with its parameters CFsize, CFguard and CFthres that is applied to the FFT output. A target list is then created from the CFAR output and the data extracted from the FFT output.</br>
All data is always transferred immediately after a measurement took place.
