MIL-STD-461G Tests: What CE102, RE102 and RS103 Mean
The naming logic of the MIL-STD-461G tests that military equipment must pass, and the most requested CE102, RE102 and RS103 tests, in plain language.
3 min readOctober 21, 2026
Distance Is Also Protection
Unintended signals from computers and displays weaken with distance from the source. How close someone who wants to eavesdrop can get to the equipment determines whether the leakage can be captured.
TEMPEST zoning is based on this simple fact. Each area within a facility is assigned to a zone according to its distance to the nearest uncontrolled point and the attenuation the walls provide.
Zones and Equipment Levels
In NATO practice, zones are usually numbered 0 to 3. Zone 0 refers to unprotected areas very close to the outside; Zone 3 refers to areas deep within the facility that provide high attenuation.
Equipment is also classified by SDIP-27 levels. In an area offering less protection, lower-emission equipment must be used. Assessing zone and equipment level together gives balanced protection.
How Is a Zone Measured?
Zoning is based on measuring the attenuation an area provides to the outside. Measurements are taken at different frequencies along building walls, windows and doors, and the results are evaluated using the method described in SDIP-28.
If the measured result doesn't achieve the expected zone, there are two options: choose a more protected area, or shield the area to increase attenuation. The second means building a TEMPEST room.
Raising the Zone with a Shielded Room
A shielded room can raise a low-zone area to the highest zone in a single step. That way an office processing classified information can be used safely even if it's close to the building facade.
Costs fall when zoning is addressed at the very start of facility planning. During the survey we measure the areas and decide together which rooms need shielding. For the basics, see our What is TEMPEST article.
Frequently Asked Questions
Who performs zoning measurements?
Organizations authorized by national security authorities, or specialist teams working with methods those authorities accept.
Must every room processing classified data be shielded?
No. If the area already provides enough attenuation and suitable-level equipment is used, shielding may not be needed.
Can a zone change over time?
Yes. New buildings nearby, new windows or renovations can affect attenuation, so periodic checks are recommended.
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