One of the main constraints of a radar in an environment with buildings, vehicles and infrastructure is called saturation. Saturation occurs when the RF energy reflected from the objects around the radar is so high that it exceeds the capacity of the receive circuit, effectively creating a “wash out” effect, causing dropped tracks, ghost tracks, and overall system confusion.
A good way to visualize what is happening for a scanning radar is to use a camera (even a simple cellphone camera), a mirror, and a flashlight with a focused beam. Set up the camera so it faces the mirror. Turn off all other lights and then point the flashlight at the mirror so the light reflected from the mirror lines up with the camera's lens. This will cause the camera light sensor to “wash out”, turning the screen white.
The screen "washes out" because the light is so concentrated that it overwhelms the camera's light-intake capacity. Because of this, the camera's light sensor can't distinguish the more subtle light sources in the room, which means it can't see the objects, shadows, or even the dimensions of the room. It is temporarily blind. Almost anything could happen in the room, and the camera wouldn't pick it up.
Scanning radars are more susceptible to this type of issue because they spend less time on target and have to pack more energy into the small time they spend on one spot. That means that when reflections occur with a scanning radar, it causes a bright flash that washes out the picture or causes ghost tracks similar to what is shown above.
In comparison, a Volumetric Persistent Radar (VPR)—or Staring radar—transmits less energy with a wide beam for a longer period of time. That way, even when there is light reflected, incoming data is much less likely to create the “wash out” effect, ensuring that all of the targets remain visible. Here is an example below using a diffuse light source, which is similar to what a VP radar does.
In conclusion, VP radars maintain more reliable threat-detection awareness, especially over large areas, than scanning beam radars. Modern security threats, including drones, are fast—too fast for vital locations to afford the occurrence of ghost tracks, false alerts, and "wash outs" in their security systems.
Early detection is paramount to protecting critical infrastructure sites, soldiers, and high-value private property from increasingly fast and destructive modern security threats. Security systems that provide constant, uninterrupted situational awareness empower faster and more accurate threat responses. In other words, if you're first to detect, you can be first to protect.