Any smart parking system has to begin with an accurate detection system.  The ability to tell if a car is in the space, or not.  Sounds simple, but it's not.  Many legacy parking vendors will tout their detection system, but unfortunately single-source detection systems are notoriously inaccurate.  Each individual technology has it's own short comings that will lead to parker confusion and frustration once it is deployed out in the wild parking jungle.  We have done significant video analysis (ask legacy vendors about their video analysis) on millions of parking sessions that has led us to develop, and constantly improve, our patent-pending algorithm that uses the best that each current detection technology can provide and fuses them together to provide a more powerful and accurate solution.  Two key differences that separate Sentry from the legacy vendors are video and processing power.  The ability to "see" the space with video and use multiple computer vision algorithms and cognitive learning in concert with sensor (puck or radar) data, along with the local processing power (because we're not constrained with limited power sources) to crunch all that data in the meter itself and quickly provide the right answer a smart system requires.