Mitigating Notch Filtering: Compensation Techniques for Notching a Received Waveform

In recent years, the demand for spectrum usage has surged significantly. This increased activity has led to congested spectral environments, presenting challenges for radars in operation. While ultra-wideband radars are useful for highprecision range detection, they are difficult to realize due to the presence of interference in many geographic locations within the receiver band. Interference to radar receivers can cause a variety of challenges, including signal distortion from saturated low-noise amplifiers (LNAs) and decreased signal-to-interference-plus-noise ratio (SINR). A solution to avoid these issues is by implementing notch filters into the radar front-end. Adding a notch filter will effectively block known interferers prior to the LNA, helping to prevent saturation and SINR issues. However, the notch filter addition distorts the received waveform, reducing precision in the correlation operation. This paper discusses how compensation can be performed for the presence of a known receiver filter notch to improve the precision of the correlation and, hence, range detection. The compensation is performed in both magnitude and phase of the received signal, and can return most of the precision initially lost through the notch filter.