Meaning
Software modifications to a software-defined radio that alter the frequency range or modulation type require a regulatory review of the updated executable code. A Class III permissive change governs these software adjustments without requiring the physical assembly to undergo new mechanical or electrical hardware certification. This category applies exclusively to devices where the operating software is secured against unauthorized modification, ensuring that user-installed applications cannot alter the core transmission parameters.
Software Security
Manufacturers must implement cryptographic protection to prevent users from loading unapproved firmware that could exceed authorized transmission limits. The digital signature must be verified by the bootloader before any executable code runs on the radio processor. This security prevents the device from being reprogrammed to operate on forbidden frequencies.
Regulatory Submission
The documentation submitted to the certification body must include high-level descriptions of the software change and the security architecture. Testing logs must demonstrate that the updated software does not cause the radio to exceed its certified output power or bandwidth. This submission allows the original FCC grant to be updated with the new software version number.
Code Validation
Operating parameters are locked within the compiled image and cannot be modified by user-accessible interfaces. Engineers run automated regression tests to confirm that spurious emissions remain within legal limits across all operating bands. The certified firmware version is then logged in the regulatory database to maintain traceable compliance.
