Offline Elliptic Curve Signature Verification Protocols for Custom Label Transponders
Offline transponder signature validation relies on compact elliptic curve keys, efficient memory framing, and compliant reader radio power limits.
FCC Part 15.225
Meaning
Federal regulatory standards define the operating conditions and electromagnetic field strength limits for intentional radiators functioning within the high-frequency band of 13.110 to 14.010 megahertz. The regulation designated as fcc part 15.225 establishes these parameters to prevent interference with authorized radio services. It applies to transceivers and active RFID readers operating at 13.56 megahertz.
Emission Limit
Strict field strength limits are imposed on the fundamental frequency to prevent degradation of adjacent bands. Under the provisions of fcc part 15.225, the field strength must not exceed 15848 microvolts per meter at a distance of 30 meters. This limit drops sharply as the frequency deviates from the 13.56 megahertz carrier.
Outside the designated band, general radiated emission limits must be met to ensure compliance.
Testing Protocol
Laboratory measurements are conducted on an open area test site or inside a semi-anechoic chamber to confirm compliance. An engineer verifies the radiated emissions of fcc part 15.225 devices across a wide frequency range. This procedure involves rotating the equipment under test and adjusting the receive antenna height.
The laboratory generates a formal test report that serves as the basis for the declaration of conformity.
Compliance Outcome
Achieving certification is a prerequisite for marketing the device in the United States. When a designer integrates an RFID module, fcc part 15.225 dictates whether the complete assembly requires full testing or can inherit the module’s modular approval. If the antenna or trace layout is modified, a class two permissive change is typically required.
This transition must be completed before the product can be legally distributed or sold.