Most degausser manufacturers offer some type of magnetic field sensor. They are designed to measure the internal magnetic field strength of a degausser. These sensors give the end user a measurement that indicates the strength of the magnetic field. If the strength is low, the sensor may prompt the end user to contact the manufacturer. Although these devices are handy, for those degaussers that are used to delete highly sensitive information in High Security Government Agencies (i.e. US Military) and appear on the National Security Agency (NSA) Evaluated Products List (EPL), the NSA indicates that “customers that acquire these products should have them re-tested periodically”. A re-testing through the use of a re-certification where data is actually erased and then analyzed to determine if it is recoverable is certainly a more prudent method in determining the continued functionality of the system.
Many degaussers, including the SEM Model EMP1000-HS Degausser, have built-in magnetic field sensors. These sensors are reliable in most cases because they are designed specifically for that unit. There are also external magnetic field sensors which can be placed in a variety of degaussers from different manufacturers. They are usually shaped like a small hard disk or tape. When using these external sensors it is very important to read and follow the instructions carefully. In many cases special adapters are required. The instructions may have a list of several degausser models with recommended ranges that each one should fall into. These are not pass/fail readings. It is only a range recommended based on the manufacturer’s testing. If the readings do fall out of range then it may make sense to have a recertification or maintenance performed.
The true intention of these sensors are there to help the end user know that something has changed regarding the magnetic field and that it may be necessary to have a recertification or service performed. Strong marketing campaigns have touted these sensors to be more than what they are. In some cases, organizations have made policy based on the magnetic sensors. This marketing is designed so that end users become reliant on sensors ultimately leading to more frequent service on their equipment or potential upgrade opportunities.
Are magnetic sensors a good thing? Yes, they are another line of defense to tip the end user of how their degausser is performing, but the only way to truly check degausser performance is to have it recertified and follow the required testing policies of NSA or your governing organization.
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