An example of a modern set-up might work as follows: the employee carries a portable electronic sensor (PES) or electronic data collector which is activated at each checkpoint. Checkpoints can consist of iButton semiconductors, magnetic strips, proximity microchips such as RFIDs or NFC- or optical barcodes. The data collector stores the serial number of the checkpoint with the date and time. Later, the information is downloaded from the collector into a computer where the checkpoint's serial number will have an assigned location (i.e. North Perimeter Fence, Cell Number 1, etc.). Data collectors can also be programmed to ignore duplicate checkpoint activations that occur sequentially or within a certain time period. Computer software used to compile the data from the collector can print out summaries that pinpoint missed checkpoints or patrols without the operator having to review all the data collected. Because devices can be subject to misuse, some have built-in microwave, g-force, and voltage detection.