In recent years, the most significant problem for police radar equipment has been radio frequency interference (RFI). The Stalker Radar company has reported the development of radar units that address this problem by digitizing the antennas that receive the Doppler signal. The units use third-generation computer technology with two sets of microwave circuits and amplification circuitry to create a high-speed, bi-directional communications link that transmits the information between the antenna and the counting unit. Decatur Electronics Inc. touts a "RFI hardened" radar system that uses twin signal filters in the Genesis II Select radar unit. MPH Industries and Kustom Signals have also developed radar designs that claim to solve the RFI problem. A related interference issue pertains to radar use in motion, which requires compensating for the ground speed of the cruiser. This article explains the technologies developed by various companies to address this issue. Other challenges that are being addressed with new radar technology are the detection of a faster target in the presence of a larger vehicle, the distinction between approaching and departing vehicles, methods for defeating radar detectors, and improved unit construction. The article concludes with an explanation of the technology as well as the advantages and limitations of lidar (light detecting and ranging), which uses light instead of radar for speed determination.