In 1992 the FCC expanded the Ka band spectrum allocated for traffic radar use to 33.4 - 36 GHz. The radar cycles between a number of different frequencies. The main beam of the radar paints only a small portion of the road. Photo radars , or camera radars as they were first called, were in experimental stages of development as early as 1954 using S band radars. In 1983 the state of Texas tried a French-manufactured Ka band radar for a time but discontinued its use because the units were being stolen right off the road.
Some units function at night by using a flash.
Many photo radars connect to a computer or printer to retrieve stored data statistics such as number of violations, time and speed of each violation, etc. Note that the registered vehicle owner may not be the driver, but the owner still gets the ticket. Some Safety Radars only display speeds above the limit, some display all speeds measured. Some units record all speeds measured, some only record speed violations. Safety Radars usually do not record the driver or vehicle, unless connected to a camera.