Sample quantity is determined by the test items and worst-case combinations, not by a fixed number. The conventional approach is to reserve one testable unit for each of the four categories—conducted emissions, radiated emissions, bandwidth, and power—plus one spare unit for retesting and teardown inspection.
| Certification/Test Type | Recommended Sample Quantity | Key Conditions |
|---|---|---|
| FCC SDoC (wired/unintentional radiator) | 2-3 units | Includes 1 spare; must be openable |
| FCC ID (wireless) | 3-4 units | Add 1 unit for each additional RF format on multi-format products |
| CE RED (wireless) | 3-4 units | Must support fixed-frequency and adjustable power modes |
| CE EMC + LVD | 2-3 units | Must run continuously at full load |
| Multi-mode/multi-band products | 4+ units | Stacked by number of RF combinations |
The SDoC cycle is 1-2 weeks. FCC ID and CE RED with radio frequency typically take 3-6 weeks, with remediation time counted separately. The direct consequence of insufficient samples: a unit that finishes radiated emissions cannot proceed to immunity testing, so new samples must be submitted and the entire schedule slips.
Because certification tests the unit that will actually be sold, not a tweaked prototype in the lab. Common errors cluster into these categories:
These differences are invisible in the lab but will be caught by market surveillance. The certification report corresponds to the submitted state; once the production state diverges from the submitted state, the report becomes invalid.
The critical component list (CDF/BOM) must be finalized before sample submission, and every critical component must have a traceable certificate. Critical components typically include: wireless modules, crystals, power adapters, batteries, optocouplers, transformers, fuses, and flame-retardant enclosure materials.
Documentation to prepare:
A certified module does not mean the complete product is exempt from testing. The complete product still requires radiated emissions, conducted emissions, and other partial tests; the module's FCC ID can only serve as a basis for exemption from certain tests, and the specific exemption scope follows the conditions under which the module was certified.
Because RF parameters are determined by software—change the firmware and test results cannot be reproduced. Before sample submission, freeze the following and record version numbers:
After freezing, if firmware changes are needed and RF-related parameters are involved, reassess whether supplementary testing is required. Changes involving only display, UI, or non-RF functions can be filed with a change description, but version comparison records must be retained.
First determine whether the non-conformance is a "test problem" or a "state problem"—the remedies differ. A test problem means insufficient margin or exceedance, requiring remediation and retesting; a state problem means the sample does not match production or documentation is missing, requiring new samples.
Common remediation measures include: adjusting filter component parameters, adding shielding and grounding, modifying antenna matching, reducing power at specific frequencies, and optimizing PCB layout. After remediation, run a pre-test to confirm margin before formal retesting. If critical components are replaced, update the critical component list and corresponding certificates accordingly.
The number of retests and the cycle depend on remediation rounds; typically each round of remediation plus retest takes 1-2 weeks. It is advisable to reserve a spare unit at first submission so that testing is not blocked during remediation.
No—you cannot submit only the mainboard. Radiated emissions, immunity, and other tests are closely tied to the complete product's structure, cabling, and enclosure, so data measured from a mainboard alone cannot represent the complete product. Complete-product submission is the minimum requirement.
Typically 2-3 units. Module certification can exempt certain test items, but the complete product still requires radiated emissions, conducted emissions, and other tests; the specific exemption scope is determined by the conditions of the module certification.
Yes, but it lengthens the cycle. Test items have sequential dependencies, and the time for round-trip shipping and re-commissioning usually exceeds the cost of preparing enough samples at once.
Firmware changes involving RF parameters should halt testing and be reassessed. Changes involving only non-RF functions require retaining version comparison records and informing the testing party.
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