Spectrum Analysis Considerations for Radar Chirp Waveform Spectral Compliance Measurements

The measurement of a radar chirp waveform is critical to assessing its spectral compliance. The Fourier transform for a linear frequency-modulated chirp is a sequence of frequency-domain impulse functions. Because a spectrum analyzer measures the waveform with a finite-bandwidth intermediate-frequency (IF) filter, the bandwidth of this filter is critical to the power level and shape of the reported spectrum. Measurement results are presented that show the effects of resolution bandwidth and frequency sampling interval on the measured spectrum and its reported shape. The objective of the measurement is to align the shape of the measured spectrum with the true shape of the signal spectrum. This paper demonstrates an approach for choosing resolution bandwidth and frequency sampling interval settings using the example of a linear frequency-modulation (FM) chirp waveform.