01. Part 15 applies to:

a. Intentional radiators (low-power transmitters intended to transmit a modulated radio signal "through the air")

02. Interference and Use of Part 15 Devices

a. Part 15 devices must not cause harmful interference (that disrupts licensed radio services), even if the devices conform to the Part 15 technical standards.

b. Users of Part 15 devices must accept any interference caused by licensed radio services.

c. Any user of any Part 15 device must stop operating the device if notified by the FCC that the device is causing harmful interference, and may not use the device until the interference problem is corrected.

d. Users of Part 15 devices are not protected against each other's interference.

e. Users of Part 15 devices do not have and can not obtain any right to use any device, frequency, or emission type.

04. Part 15 devices must be constructed per good design and manufacturing practices to not emit any signal that is not in accordance with FCC Regulations.

a. Part 15 devices must suppress extraneous signals as much as practicable. In general:

(1) No extraneous signal can be stronger than the desired or intended signal.

(2) Extraneous signals must usually be at least 20 dB below the level of the desired signal.

(3) All signals less than 20 dB below the level of the desired signal must be contained within an authorized band, or a bandwidth within that band.

05. This notice must be affixed to the enclosure of a Part 15 device that is home-built or is not allowed to carry a different notice or identifier: This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions:

(1) This device may not cause harmful interference, and

(2) this device must accept any interference received, including interference that may cause undesired operation.

If the device is in two or more parts, the notice must be affixed to the enclosure of the main control unit.

If any of the enclosures is too small to affix the notice to it, the notice must be placed on the packaging or in the documentation for the device.

06. Home-built devices that are not made from a kit (any packaged collection of electronic parts, whether complete or not) and that are built in quantities of five or less for personal use, do not have to be authorized by the FCC (see Section 15.23).

Home builders who do not have test and measurement equipment to determine precise compliance with technical standards must use good engineering practice to meet those standards to the greatest extent practicable.

07. Makers and users of Part 15 devices must make those devices and any required documentation available for FCC inspection "upon reasonable request." Any information or documentation requested by the FCC must be provided promptly to the greatest practical extent. The FCC may require that any Part 15 device be shipped (at the maker's or user's expense, both ways) to the FCC Laboratory in Columbia, Maryland, to be tested for compliance with applicable technical standards in force on the date of manufacture.

08. Power measurements:

a. The maximum radiated field strength, or the input power to the device or the final RF amplifier if appropriate, must be measured:

(1) With a new battery for a battery-powered device, OR

(2) With the supplied voltage varied between 85% and 115% of normal for an AC-powered device.

b. Field strength, or input power if appropriate, must be measured with:

(1) Any user-accessible controls adjusted for maximum emitted signal, AND

(2) Any specified or appropriate leads or cables attached, each one meter (just under 39-3/8 inches) long, or as long as normally needed, generally whichever is greater.

c. Multiple-component devices or systems must be tested with all components (including available accessories):

(1) Connected and operating ("operating" including "emitting" for multiple emitters), AND (2) Arranged for maximum total emissions within the expected range of configurations.

d. Field strength is not usually measured by home builders. However, if measured:

(1) It must be measured at the prescribed distance(s) unless impractical, in which case the circumstances must be recorded and a correction factor must be determined and applied.

(2) The prescribed distance(s) apply from the point of measurement to the device, support equipment, or interconnecting cable(s), whichever is closest

09. Part 15 home-built transmitters are usually built to operate on a particular frequency, and otherwise virtually always to operate over a frequency range of 1 MHz or less. If a home builder can obtain the use of test and measurement equipment normally considered to be commercial-grade or better:

a. Signal measurements must be made when the transmitter is operating on the intended frequency or the center frequency of the range.

b. Checks for extraneous signals must be made up to a frequency that is ten times the intended frequency or the upper frequency of the range (but not higher than 40 GHz).

11. Low-power transmitters may be used in the following bands:

f. (15.239) 88-108 MHz

(1) All intended emissions confined within band limits and within bandwidth of 200 kHz centered on operating frequency

(2) Field strength of any emission:

(a) Within 200-kHz bandwidth not over 250 microvolts/meter at 3 meters (note: The June 1989 revised rule specifies a maximum of 250 µV per meter, but measured at 3 meters from your antenna. The term, "250µV per meter" means that an accurate field-strength meter with a calibrated and scaled 1-meter antenna may indicate a maximum signal field strength of 250µV)

FCC Public Notice: Permitted Forms of Low Power Broadcast Operation