Basically these technologies rely on a number of components working in harmony. There are the various technologies that are all built into an ankle bracelet, including GPS devices and a cellphone type of device. These devices also rely on networks working.
Regarding the statement about 40% to 60% inaccuracies, that type of inaccuracy has never been my experience. When we look at the fact that a typical GPS bracelet can collect hundreds and up to thousands of points in the space of only four hours, that has never been my experience. A very small percentage of those might occasionally not be accurate.
The inherent accuracy of these devices falls within 10 meters, or about 30 feet, when we're talking about GPS signals. They're a little less accurate if we're talking about indoor tracking technology, which is not the same as satellite technology.
The 40% to 60% inaccuracy has not been my experience. It's not even close, but that has to be taken in the context of setting up these technologies for use on offenders or accused persons. If the zones that they should or should not be in are not properly configured, that can lead to what I would call “nuisance alerts”. These are alerts that weren't meant to be triggered but happen because of an improper configuration.
The 40% to 60% has certainly not been our experience. These devices have a lot of moving parts. Generally speaking, of the thousands of points that are collected in a day, a very small number may be inaccurate.