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AN4378

An overview of FCC regulations

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1

An overview of FCC regulations

Low power, non-licensed devices operating in the 2400 - 2483.5 MHz band are found

everywhere, such as toys, wireless security systems, wireless telemetry, wireless automatic

meter reading applications, and so on.

The FCC is the body responsible in the USA for implementing rules limiting the potential for

interference to licensed operations by low power, non-licensed transmitters. These rules are

documented in Part 15 of Title 47 of the FCC.

For operation in the 2400 - 2483.5 MHz band, a low power, non-licensed device must meet

one of the following sub-parts of the regulation:

–

Part 15.247: devices that operate to this part are limited to frequency hopping and

digitally modulated scheme.

–

Part 15.249: this sub-part does not enforce restrictions on either modulation

scheme or the end application.

The FCC classifies Bluetooth BR/EDR as an FHSS system. However, Bluetooth LE does

not fulfill these requirements. Instead, the FCC classifies Bluetooth LE as a system using

digital modulation techniques.

1.1

Part 15.247

To be compliant with the FCC part 15.247 digital modulation scheme, the devices or

systems must meet the following requirements:

1.

The minimum 6 dB bandwidth of the signal shall be at least 500 kHz.

2.

The maximum permitted peak conducted output power is +30 dBm (1 W). However, the

power spectral density conducted from the intentional radiator to the antenna shall not

be greater than 8 dBm in any 3 kHz band during any time interval of continuous

transmission.

3.

In any 100 kHz bandwidth outside the frequency band of operation the power shall be

at least 20 dB below that in the 100 kHz bandwidth within the band that contains the

highest level of the desired power.

4.

Radiated harmonic and spurious emissions which fall within the restricted bands, as

defined in FCC part 15.205 must comply with the radiated emission limits specified in

FCC part 15.209.

A detailed guide document called “Guidance for Performing Compliance Measurements on

Digital Transmission Systems (DTS) Operating Under Part 15.247” was written from FCC

[3]. Here, this guidance is followed when performing the FCC part 15.24 compliance

measurements.

1.2

Parts 15.205 and 15.209

As previously described, radiated harmonics and spurious emissions of devices that comply

with part 15.247, which fall within the restricted bands as defined in FCC part 15.205, must

comply with the radiated emission limits specified in FCC part 15.209. For any 100 kHz

bandwidth outside the frequency band of operation and outside the restricted bands, the

power shall be at least 20 dB below that in the 100 kHz bandwidth within the band that

contains the highest level of the desired power.