Users need to know about GPS jammers for better use
GPS jammers come in a variety of sizes and configurations, the design you're most likely to encounter includes an adapter that includes 1-3 antennas and plugs into a cigarette lighter. Employees have been using GPS technology since its introduction in 1990. Since then, a game of cat and mouse has been played between GPS engineers and staff. In most organizations, employees inform their colleagues of the ability to "beat" the system, leading to increased use of GPS jammers in stores, regions, or companies.

So how do you know someone is using a GPS blocking device to jam the signal? It's not that simple. They make decisions based on the lack of information. Many employers blame GPS devices, lost cellular service, or dead GPS signal spots. Recorded data is difficult to record due to the lack of information to record anything. Since most employers don't understand wireless technology, they think these excuses are all within the scope of opportunity, so they place the blame on GPS tracking devices.
GPS jammers can cause random loss of GPS data. In most cases it doesn't happen at a specific time on a specific day of the pattern. Employees use GPS jammers to do what they need to do to schedule company time, such as having lunch with friends, doing business, picking up kids from school or going home early.
These behaviors are mostly random, which could be a clue. Another clue is seeing similar GPS tracking behavior across business units and industries. Because the driver provides a "jump system," others will mimic the behavior you'll see over time, adding to the random loss of GPS data between vehicles.
You can compare a number of data sources showing accumulated mileage, RPM rises and falls, lower tank levels, and more. All of these things don't solve the mystery, but they create enough environmental evidence to warrant action.