答：其實準確的說 FCC Part 15 B應該是FCC Part 15 Class B（B級數(shù)字裝置）。
Class A和Class B的定義：
Class A digital device－A級數(shù)字裝置.
A digital device that is marketed for use in a commercial, industrial or business environment, exclusive of a device which is marketed for use by the general public or is
intended to be used in the home.投放市場供在商業(yè)、工業(yè)或商務環(huán)境中使用的數(shù)字裝置，但不包括投放市場供一般公眾或家庭使用的裝置。
Class B digital device－B級數(shù)字裝置.
Class B digital device. A digital device that is marketed for use in a residential environment notwithstanding use in commercial, business and industrial environments. Examples of such devices include,
but are not limited to, personal computers, calculators, and similar electronic devices that are marketed for use by the general public. Note: The responsible party may also qualify a device intended to
be marketed in a commercial, business or industrial environment as a Class B device, and in fact is encouraged to do so, provided the device complies with the technical specifications for a Class B digital device.
In the event that a particular type of device has been found to repeatedly cause harmful interference to radio communications, the Commission may classify such a digital device as a Class B digital device, regardless
of its intended use.投放市場不僅供在商業(yè)、工業(yè)或商務環(huán)境中使用而且要在居住環(huán)境中使用的數(shù)字裝置。這類裝置的例子包括（但不限于）：個人計算機、計算器以及其它投放市場供一般公眾使用的類似電子裝置。
注：職責部門也可以把投放市場以供商業(yè)、工業(yè)或商務環(huán)境中使用的裝置定義為B級裝置；事實上FCC也鼓勵這一舉措，只要該裝置能滿足B級裝置的技術規(guī)范。若某類型裝置反復地對無線電通訊產生有害干擾，
則FCC可能會將之歸為B級數(shù)字裝置而不管其用途如何。
問題1：FCC的目錄？
答：下面是FCC PART 15目錄章節(jié)內容：
Subpart A – General（一般要求）
Subpart B - Unintentional Radiators（無意輻射體）
Subpart C - Intentional Radiators（有意輻射體）
Subpart D - Unlicensed Personal Communications Service Devices
Subpart E - Unlicensed National Inbation Infrastructure Devices
Subpart F – Ultra-Wideband Operation
Subpart G – Access Broadband Over Power Line (Access BPL)
問題3：有意輻射體和無意輻射體的定義
答：Intentional radiator（有意輻射體）－定義. A device that intentionally generates and emits radio frequency energy by radiation or induction. 通過輻射或感應的方式有意產生和發(fā)射RF（射頻）能量的裝置。
注：紅外線設備（比如：紅外線遙控器）因為紅外線不屬于RF（射頻），所以它不屬于有意輻射體。另外，如果紅外線設備的clock frequency（時鐘頻率）小于9KHz，那么它也不需要FCC Doc測試；
如果clock frequency（時鐘頻率）大于9KHz，那么它需要FCC測試，必須符合FCC Part 15.209（Radiated emission limits.－輻射測試）
Unintentional radiator（無意輻射體）－定義. A device that intentionally generates radio frequency energy for use within the device, or that sends radio frequency signals by conduction to associated equipment via
connecting wiring, but which is not intended to emit RF energy by radiation or induction.有意產生射頻能量供給裝置內部使用或通過連線將射頻信號傳送給有關設備使用，但不是有意輻射或感應的方式來發(fā)射射頻能量的任一裝置。
