Evaluating Class Two Permissive Change Triggers for Encapsulated Modules
Class Two Permissive Changes are triggered when physical, antenna, or firmware modifications alter RF emissions or RF exposure without exceeding original grant limits.
Duty Cycle SAR Calculations
Meaning
Mathematical procedures for scaling measured specific absorption rate values account for the temporal variations in radio frequency exposure from a wireless device. Duty cycle sar calculations adjust the raw data collected during lab tests to reflect the maximum possible exposure over a specific period. These adjustments are necessary when a device does not transmit continuously at peak power.
Scaling Factor
The factor represents the ratio between the maximum rated duty cycle and the duty cycle used during the laboratory test. If a device is tested at one hundred percent transmission but is software limited to fifty percent in the field, duty cycle sar calculations reduce the reported exposure levels.
Software Implementation
Firmware controls the duration and frequency of transmission bursts to maintain the declared average power levels. Duty cycle sar calculations rely on the integrity of these software locks to stay within regulatory limits. Validation involves checking that the source based time averaging cannot be exceeded by a user or an external application.
This process requires a detailed review of the source code or an attestation from the software engineering team to ensure the duty cycle cannot be altered by third party programs.
Compliance Margin
Legal margins between the calculated exposure and the threshold determine if the device can be sold in specific markets. Failure to provide accurate duty cycle sar calculations results in testing delays or rejection of the certification filing.