FCC Part 15 Testing — The Definitive Guide

FCC part 15 testing governs the use and marketing of electronic devices in the United States that emit radio frequency (RF) energy, whether intentionally or unintentionally. Compliance with these rules is mandatory before you sell or put most electronic products into the U.S. market.

1. What Is FCC Part 15?

FCC Part 15 is part of Title 47 of the Code of Federal Regulations. The rules aim to prevent harmful interference to licensed services like broadcast radio, mobile phones, emergency communications, and aviation systems.

Part 15 applies to three broad categories of devices:

• Incidental Radiators: Devices that unintentionally produce RF emissions as a byproduct (e.g., power tools, motors, switching power supplies).

• Unintentional Radiators: Digital electronics that generate RF energy internally but don’t intentionally transmit it (e.g., computers, microcontroller systems).

• Intentional Radiators: Devices designed to emit RF energy intentionally (e.g., Wi‑Fi modules, Bluetooth, remote controls).

Every regulated device must comply with specific limits on emissions and undergo appropriate testing before it can be marketed.

2. Why FCC Part 15 Testing Matters

Part 15 testing is critical for several reasons:

🎯 Legal Market Access — Without compliance, products cannot legally be sold or marketed in the U.S.
🔊 Interference Protection — Ensures devices operate without disrupting licensed communications.
📑 Regulatory Documentation — Test results and reports form the legal basis for FCC authorization.

Manufacturers and importers are responsible for ensuring compliance — the FCC does not routinely test every product itself, but reviews the testing data manufacturers submit.

3. Types of FCC Part 15 Authorization

Different kinds of equipment require different procedures:

A. Certification

Required for intentional radiators (wireless transmitters).
A Telecommunications Certification Body (TCB) or the FCC reviews test data and issues a Certification and an FCC ID.

B. Supplier’s Declaration of Conformity (SDoC)

Usually used for unintentional radiators and some digital devices.
The manufacturer tests the device at an accredited lab and declares conformity without direct FCC review.

C. Verification

Occasionally used for basic devices with predictable emissions; manufacturers maintain records that show compliance.

Each path requires specific documentation and labeling. The details vary by device type and use case.

4. Core FCC Part 15 Tests

The heart of Part 15 compliance is Electromagnetic Compatibility (EMC) testing, which includes:

A. Radiated Emissions

Measures RF energy leaking into the air from the device across defined frequency ranges. Testing is typically performed in an Open Area Test Site (OATS) or an anechoic chamber, at a set distance like 3 meters.

B. Conducted Emissions

For devices connected to AC mains, measures RF energy injected back onto power lines via a Line Impedance Stabilization Network (LISN).

Tests follow recognized standards like ANSI C63.10 for unlicensed wireless devices — this standard defines how to set up the test, stimulate the equipment under test (EUT), and measure emissions.

5. Radiated Emissions — What It Looks Like in Practice

In a typical radiated emissions test:

• The device (EUT) is placed on a turntable.

• A test antenna is positioned several meters away.

• The EUT operates in its worst‑case mode to maximize emissions.

• The antenna rotates and changes polarization to capture maximum signal levels.

This helps ensure the most conservative measurement of emissions for compliance.

6. Key Standards and Reference Rules

Compliance testing generally adheres to:

📌 47 CFR Part 15 – The FCC’s legal rules for emissions and RF devices.
📌 ANSI C63.10 – Test procedures for unlicensed wireless devices.
📌 ANSI C63.4 – Methods for measuring RF emissions from low‑voltage equipment.

Depending on device type and frequency of operation, other regulatory standards may also apply.

7. Testing Workflow — Step by Step

Here’s a practical workflow for FCC Part 15 compliance:

1. Design for Compliance:
   Build with EMC in mind (good grounding, decoupling, shielding, module reuse).

2. Classify the Device:
   Determine intentional vs. unintentional radiator and applicable subparts.

3. Pre‑Scan / Pre‑Compliance Testing:
   Optional — helps catch issues early using in‑house tools.

4. Lab Testing:
   Submit the device to an FCC‑recognized, accredited lab for emissions testing.

5. Documentation:
   Collect test reports, procedure descriptions, labeling, and manuals.

6. Submit for Authorization:
   For intentional radiators, submit to a TCB or FCC for certification.

7. Labeling & User Manual:
   Add FCC ID (if applicable) and required compliance statements.

8. Maintain Records:
   Keep test results and documentation for FCC inspection if requested.

8. Costs, Timelines & Tips

• Costs vary widely — from a few thousand dollars for basic emissions testing to $10,000+ for intentional radiators.

• Timelines typically range from 2 weeks (SDoC/Verification) to multiple months (Certification).

• Using pre‑certified modules (e.g., Wi‑Fi or Bluetooth radio modules) can reduce testing scope.

• Work with experienced accredited labs — they can help interpret applicable standards and avoid costly re‑tests.

9. After Certification — Ongoing Compliance

Even after passing initial testing and receiving authorization, it’s important to:

✅ Monitor for design or component changes (which can affect compliance)
✅ Maintain records in case the FCC requests them
✅ Keep up with regulatory updates

Part 15 rules and referenced standards are periodically updated, so staying informed helps avoid future compliance issues.

10. Common Mistakes to Avoid

❌ Waiting until the final prototype to test — early testing saves time and cost.
❌ Assuming a pre‑certified chip or module covers the entire product.
❌ Ignoring documentation and labeling requirements.
❌ Attempting to self‑certify without proper lab support.

Conclusion

FCC Part 15 testing isn’t optional — it’s a legal gateway to selling electronic products in the U.S. market. Whether your device is a simple digital sensor or a complex wireless radio, understanding what Part 15 requires and planning for compliant design and testing will save time, money, and headaches.