An overview of FCC regulations

AN4126

4/28

Doc ID 023299 Rev 1

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An overview of FCC regulations

Low power, non-licensed devices operating in the 902 - 928 MHz band can be found

everywhere, in toys, wireless security systems, wireless telemetry or wireless automatic

meter reading, and so on.

The FCC is the USA body responsible for implementation rules to limit 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 902 - 928 MHz band, a low power, non-licensed device must meet one

of the following sub-parts of the regulation:

●

Part 15.243: operation is restricted for devices to use radio frequency energy to

measure the characteristic of a material. Voice communication or other data

transmission is not permitted.

●

Part 15.245: operation is limited to devices operating as field disturbance sensors,

excluding perimeter protection systems.

●

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

digitally modulated schemes.

●

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

the end application.

The SPIRIT1 is designed to meet the 15.247 and 15.249 sub-parts, so this document

continues with a description and measurement results of these two parts.

1.1

Part 15.247

Devices that operate to FCC part 15.247 are limited to frequency hopping and digitally

modulated schemes.

To be compliant with the frequency hopping system, the device or system must meet the

following requirements:

●

Frequency hopping systems must have hopping channel carrier frequencies separated

by a minimum of 25 kHz or 20 dB bandwidth of the hopping channel, whichever is

greater.

●

The system must hop to channel frequencies that are selected at the system hopping

rate from a pseudo randomly ordered list of hopping frequencies. Each frequency must

be used equally on the average by each transmitter.

●

If the 20 dB bandwidth of the hopping channel is less than 250 kHz, the system must

use at least 50 hopping frequencies and the average time of occupancy on any

frequency must not be greater than 0.4 seconds within a 20 second period; if the 20 dB

bandwidth of the channel is 250 kHz or greater, the system must use at least 25

hopping frequencies and the average time of occupancy on any frequency must not be