FCC required tests: Part 15, licensed radio, RF exposure

Hugues Orgitello updated 7 Oct 2026 14 min read

An FCC test report answers a short list of rule sections: 15.107 and 15.109 for the digital circuitry, 15.247 or 15.407 (or another Subpart C section) for an unlicensed radio, 2.1046 to 2.1057 for a licensed transmitter, and 1.1310 with 2.1091 or 2.1093 for RF exposure. The methods are ANSI C63 standards, in the editions the FCC has incorporated: ANSI C63.4-2014 for unintentional radiators and, since October 30, 2025, only ANSI C63.10-2020 for unlicensed transmitters. This page goes through each test as the eCFR prints it on October 7, 2026, with the parameter, the limit, the rule and the FCC guidance, and ends with the readings the texts contradict. Like the European CISPR standards, the ANSI C63 methods set how to measure; the limits themselves sit in the rules.

The test map

Test	Applies to	Rule with the limit	Method (edition in force)
AC power line conducted emissions	Unintentional radiators connected to the AC line	15.107	ANSI C63.4-2014 (15.31(a)(4))
Radiated emissions, digital device	Class A and Class B digital devices	15.109	ANSI C63.4-2014
AC power line conducted emissions, transmitter	Intentional radiators connected to the AC line	15.207	ANSI C63.10-2020 (15.31(a)(3))
Unlicensed transmitter: power, bandwidth, PSD, unwanted emissions	902-928 MHz, 2.4 GHz and 5.8 GHz DTS and frequency hopping	15.247, 15.209, 15.205	ANSI C63.10-2020, KDB 558074
U-NII transmitter, including DFS and TPC	5 GHz and 6 GHz Wi-Fi	15.407	ANSI C63.10-2020, KDB 789033, KDB 905462
Licensed transmitter: power, modulation, bandwidth, spurious, frequency stability	Cellular and other licensed services (Parts 22, 24, 27, 90 and others)	2.1046 to 2.1057 and the service Part	ANSI C63.26-2015 accepted (2.1041(b))
RF exposure	Every RF source in a certification application	1.1310, 2.1091 (mobile), 2.1093 (portable)	KDB 447498 and related KDBs (guidance, not binding)

Part 15 contains no immunity test. The 15.19 statement that a device "must accept any interference received" is a condition of operation, not a test. Which Part and section applies to which technology is on FCC Parts; which devices need Certification or SDoC is on FCC scope.

Unintentional emissions: Part 15 Subpart B

Digital devices are tested to ANSI C63.4-2014, with clauses 4.5.3, 4.6, 6.2.13, 8.2.2, 9 and 13 excluded (15.31(a)(4)). The FCC kept this edition in its 2023 standards update (88 FR 67108).

Conducted emissions (15.107)

Measured with a 50 μH/50 ohm LISN (15.31(l)), 150 kHz to 30 MHz, on each power line.

Frequency (MHz)	Class B quasi-peak (dBμV)	Class B average (dBμV)	Class A quasi-peak (dBμV)	Class A average (dBμV)
0.15-0.5	66 to 56 (decreasing with log f)	56 to 46 (decreasing with log f)	79	66
0.5-5	56	46	73	60
5-30	60	50	73	60

The Class A margin over Class B is not a fixed figure: it is 13 dB quasi-peak and 10 dB average at 150 kHz, widening to 23 dB and 20 dB at 500 kHz as the Class B limit falls, then 17 dB and 14 dB from 0.5 to 5 MHz, and 13 dB and 10 dB from 5 to 30 MHz. A device that runs only from batteries is exempt (15.107(d)); one that operates while charging from the AC line is not. The bench practice is on conducted emissions and the LISN.

Radiated emissions (15.109)

Frequency (MHz)	Class B at 3 m	Class A at 10 m
30-88	100 μV/m (40.0 dBμV/m)	90 μV/m (39.1 dBμV/m)
88-216	150 μV/m (43.5 dBμV/m)	150 μV/m (43.5 dBμV/m)
216-960	200 μV/m (46.0 dBμV/m)	210 μV/m (46.4 dBμV/m)
Above 960	500 μV/m (54.0 dBμV/m)	300 μV/m (49.5 dBμV/m)

The rule gives the μV/m values; the dBμV/m figures are 20 log of them. Detectors come from 15.35: quasi-peak up to 1000 MHz (peak allowed as an alternative), average above 1000 MHz with at least 1 MHz resolution bandwidth, and a peak limit 20 dB above the average limit. So above 1 GHz a Class B device must stay under 54 dBμV/m average and 74 dBμV/m peak at 3 m. A lab may measure at another distance above 30 MHz and extrapolate at 20 dB per decade, but not beyond 30 m without justification (15.31(f)(1)).

How high the scan goes (15.33(b))

Highest frequency generated or used in the device (MHz)	Upper limit of the radiated scan
Below 1.705	30 MHz
1.705-108	1000 MHz
108-500	2000 MHz
500-1000	5000 MHz
Above 1000	5th harmonic of the highest frequency, or 40 GHz, whichever is lower

The rule counts the highest frequency generated or used, not only the main clock. The side-by-side comparison with CISPR 32, which also prints 3 m limits, is on radiated emissions EMC test.

Intentional emissions: Part 15 Subpart C and E

Since October 30, 2025, unlicensed transmitters other than UPCS devices are measured to ANSI C63.10-2020 only; the 2013 edition was accepted for measurements made before that date (15.31(a)(3), 15.37(s)). The IEEE amendment C63.10a-2024 is not incorporated by the FCC.

Conditions common to every Subpart C test

Condition	Rule	What the text says
Supply voltage	15.31(e)	Fundamental power or field strength measured with the supply varied from 85% to 115% of nominal; battery equipment tested with a new battery
Test channels	15.31(m)	One channel (middle) if the device tunes over 1 MHz or less; two (top and bottom) for 1 to 10 MHz; three (top, middle, bottom) above 10 MHz
Configuration	15.31(g), (i)	Controls set to maximise emissions; accessories attached, one of each type of port
Radiated scan range	15.33(a)	From the lowest frequency generated (not below 9 kHz) to the 10th harmonic or 40 GHz below 10 GHz; higher ranges for 10 GHz and above; extended to the digital device range if that is higher
General radiated limits	15.209	30-88 MHz: 100 μV/m, 88-216 MHz: 150 μV/m, 216-960 MHz: 200 μV/m, above 960 MHz: 500 μV/m, all at 3 m; average detector above 1000 MHz
Restricted bands	15.205	Only spurious emissions allowed there, and they must meet 15.209
Reporting threshold	15.31(o)	Emissions more than 20 dB below the limit need not be reported

15.247: what is measured

KDB 558074 (DTS and frequency hopping measurement guidance) sets the procedures; 15.247 sets the limits.

Parameter	Limit	Rule
6 dB bandwidth, digital modulation	At least 500 kHz	15.247(a)(2)
Channel count, frequency hopping	At least 15 channels at 2.4 GHz; 75 for the full 1 W	15.247(a)(1)(iii), (b)(1)
Output power, digital modulation	1 W peak conducted; maximum conducted output power may be measured instead	15.247(b)(3)
Antenna gain	Limits assume 6 dBi or less; above that, conducted power drops dB for dB (relief for fixed point-to-point links)	15.247(b)(4), (c)
Power spectral density, digital modulation	8 dBm in any 3 kHz band; no PSD limit for frequency hopping	15.247(e)
Unwanted emissions	20 dB below the in-band peak in any 100 kHz (30 dB when power is measured as an RMS average); 15.209 in restricted bands	15.247(d)
RF exposure	1.1307(b), 1.1310, 2.1091 and 2.1093 apply	15.247(i)

Systems using DSSS or OFDM fall under the digital modulation limits; frequency hopping systems have their own channel and dwell rules in 15.247(a)(1). Each parameter is measured on the 15.31(m) channels.

15.407: what is measured

KDB 789033 covers the general U-NII procedures, KDB 905462 the DFS tests and KDB 987594 the 6 GHz devices. The full power and PSD table by band and device type is on FCC Parts.

Test	Requirement	Rule
Maximum conducted output power	Measured over any interval of continuous transmission, RMS-equivalent	15.407(a)(12)
Power spectral density	Conducted; 500 kHz reference bandwidth in 5.725-5.895 GHz, 1 MHz elsewhere (or the 26 dB bandwidth if smaller)	15.407(a)(13)
Unwanted emissions in 6 GHz	Outside 5.925-7.125 GHz, at most -27 dBm/MHz EIRP	15.407(b)(6)
Transmit power control	5.25-5.35 and 5.47-5.725 GHz: able to operate 6 dB below a mean EIRP of 30 dBm; not required below 500 mW EIRP	15.407(h)(1)
Contention-based protocol	Every 6 GHz U-NII transmitter except standard power APs and fixed clients	15.407(d)(6)
AFC	Standard power APs and fixed clients in U-NII-5 and U-NII-7 (5.925-6.425 and 6.525-6.875 GHz)	15.407(k)
Device security	Security features that protect against software modification of the RF parameters	15.407(i)

DFS parameters in 15.407(h)(2)

DFS applies to any device with part of its 26 dB emission bandwidth in 5.25-5.35 GHz or 5.47-5.725 GHz.

Parameter	Value in the rule
Detection threshold, 200 mW to 1 W EIRP	-64 dBm
Detection threshold, below 200 mW EIRP and PSD below 10 dBm/MHz	-62 dBm
Threshold definition	Received power averaged over 1 μs, referenced to a 0 dBi antenna
Sensing bandwidth	100% of the emission bandwidth
Channel availability check	60 s without radar before using a channel (master mode)
Channel move time	All transmissions cease within 10 s; normal traffic for at most 200 ms after detection
Non-occupancy period	At least 30 minutes

Licensed transmitters: Part 2 and the service Parts

A cellular module or device is certified under the licensed-service Part for each band (22, 24, 27 and others), with the measurements listed in Part 2 Subpart J. ANSI C63.26-2015 is an acceptable procedure (2.1041(b)).

Measurement	Part 2 section	What the text asks
RF power output	2.1046	Measured at the RF output terminals, with the load stated
Modulation characteristics	2.1047	Curves or data according to the modulation type
Occupied bandwidth	2.1049	Bandwidth containing 99% of the mean power (0.5% outside each edge)
Spurious emissions at antenna terminals	2.1051	Each harmonic and spurious emission, into a suitable artificial antenna
Field strength of spurious radiation	2.1053	Emissions radiated from cabinet, control circuits and power leads
Frequency stability	2.1055	With temperature varied (from -30 °C to +50 °C for most equipment) and supply voltage varied
Spectrum to investigate	2.1057	From the lowest frequency generated (not below 9 kHz) to the 10th harmonic or 40 GHz below 10 GHz

The limits come from the service Part. For example, emissions outside the authorized frequency range must be attenuated by at least 43 + 10 log(P) dB below the transmitter power P, in 22.917(a) for cellular and 24.238(a) for broadband PCS; Part 27 has the same formula with stricter values in some bands (27.53). Part 2 does not ask for EVM or for 3GPP conformance suites such as TS 36.521 (LTE) or TS 38.521 (5G NR); those belong to industry certification such as PTCRB or GCF, compared on PTCRB vs GCF.

RF exposure: SAR and MPE

The device category decides the method. A portable device is used with its radiating structure generally within 20 cm of the user's body (2.1093(b)); a mobile device is normally used at 20 cm or more and is not fixed in place (2.1091(b)).

Case	Quantity	Rule
Portable device, 100 kHz to 6 GHz	SAR	2.1093(d)(1), 1.1310(a) to (c)
Portable device above 6 GHz	MPE (power density)	2.1093(d)(1), 1.1310(e)
Mobile and fixed sources, 300 kHz to 6 GHz	MPE may be used instead of whole-body SAR	1.1310(d)(2)
Any source above 6 GHz	MPE	1.1310(d)(3)

Not every device is evaluated: a single RF source of at most 1 mW available maximum time-averaged power is exempt regardless of distance, and others are exempt below the power thresholds of 1.1307(b)(3). Even then, under the KDB 447498 transition in force since August 13, 2022 "until further notice", every certification application includes at least one RF exposure exhibit, including when it claims an exemption. Applicants use either KDB 447498 D01 v06 or the interim D04 v01, without mixing them.

SAR limits (1.1310)

Exposure	Whole body	Peak spatial average	Extremities (hands, wrists, feet, ankles, pinnae)	Averaging time
General population / uncontrolled (1.1310(c))	0.08 W/kg	1.6 W/kg over any 1 g cube	4 W/kg over any 10 g cube	30 minutes at most
Occupational / controlled (1.1310(b))	0.4 W/kg	8 W/kg over any 1 g cube	20 W/kg over any 10 g cube	6 minutes at most

Consumer devices are always assessed against the general population limits; no advisory or manual text allows them to use the occupational limits (2.1093(d)(6)). SAR can be measured or computed with a validated numerical method (2.1093(d)(2)). The EU basic restrictions in Council Recommendation 1999/519/EC average localised SAR over 10 g of contiguous tissue and over six minutes, so a US 1 g result and an EU 10 g result are not interchangeable: each market needs its own evaluation. Measurement detail is on SAR procedures; the FCC SAR guidance is in KDB 865664 (100 MHz to 6 GHz) and KDB 248227 (802.11).

MPE limits, general population (1.1310(e)(1), Table 1)

Frequency (MHz)	Power density (mW/cm²)	Averaging time
0.3-1.34	100	30 minutes or less
1.34-30	180/f²	30 minutes or less
30-300	0.2	30 minutes or less
300-1,500	f/1500	30 minutes or less
1,500-100,000	1.0	30 minutes or less

f is in MHz. The occupational limit above 1,500 MHz is 5 mW/cm², for people aware of and able to control their exposure. For a mobile device, the application states compliance with 1.1310, evaluated in general at maximum time-averaged power, and the technical basis is supplied on request; unlicensed NII devices always use the general population limits (2.1091(d)(1)). When a module or desktop transmitter cannot easily be classed as mobile or portable, the applicant sets the minimum compliance distance from SAR, field strength or power density, whichever fits (2.1091(d)(4)).

Test labs and test sites

Rule	Requirement
2.948(a)	Equipment under Certification is tested in a lab accredited under 2.948(e) and recognized by the FCC under 2.951
2.948(e)	Accreditation to ISO/IEC 17025 by an accreditation body recognized by OET, with a scope covering the measurements
2.948(f)	A lab outside the United States is accepted only if designated under a government-to-government MRA, or, where no MRA exists, accredited by a body recognized under 2.949 for that country
2.948(b)	The lab keeps a description of the test site: location, photographs, dimensions, supporting structures, measuring equipment, calibration dates and site attenuation data
2.948(d)(1) to (3)	Site validation: ANSI C63.4a-2017 or C63.4-2014 clause 5.4.4 for 30 MHz to 1 GHz; ANSI C63.25.1-2018 for 1 to 18 GHz; C63.4-2014 clause 5.5.1 with CISPR 16-1-4:2010 criteria for 18 to 40 GHz
2.948(d)(4)	Test site revalidation at intervals not exceeding three years
2.906(a)(1)	SDoC testing needs no accredited lab, but not a lab owned, controlled or directed by a prohibited entity (since FCC 25-27)

The rule speaks of accreditation plus recognition, not of an "FCC accreditation". Which TCB grants the product and how the filing works is on FCC procedure.

Dated changes that affect testing

Date	Text	Effect on testing
August 13, 2022	KDB 447498 transition	Interim D04 v01 RF exposure guidance usable "until further notice"; RF exposure exhibit in every application
October 30, 2023	FCC 23-14, 88 FR 67108	ANSI C63.10-2020 incorporated with a two-year transition; C63.4a-2017 and C63.25.1-2018 added for site validation; ISO/IEC 17025:2017 for accreditation
May 5, 2025	90 FR 11373	Very low power devices allowed across 5.925-7.125 GHz, with their own limits
September 8, 2025	FCC 25-27, 90 FR 38045	Labs owned, controlled or directed by a prohibited entity lose recognition; SDoC testing barred in such labs
October 30, 2025	15.37(s)	ANSI C63.10-2013 no longer accepted; only C63.10-2020 for new measurements
April 27, 2026	91 FR 9140	Geofenced variable power devices in U-NII-5 and U-NII-7, with their own limits; see FCC Parts

Comparison with European tests (RED)

Aspect	FCC	EU
EMC emissions method	ANSI C63.4-2014	CISPR 32 / EN 55032
Radio method	ANSI C63.10-2020 (unlicensed), ANSI C63.26-2015 (licensed)	Harmonised standards such as EN 300 328 and EN 301 893
Radiated limit distance	Class B at 3 m, Class A at 10 m	CISPR 32 gives 10 m and 3 m limits
2.4 GHz power	1 W conducted with up to 6 dBi antenna gain	100 mW (20 dBm) EIRP under EN 300 328
Immunity	None in Part 15	Required (EN 55035 for multimedia equipment)
SAR averaging	1 g cube, 30 minutes	10 g contiguous tissue, six minutes
Cybersecurity	No mandatory test in the equipment authorization rules	RED Article 3(3)(d), (e), (f) delegated act applies from August 1, 2025

Claims the texts contradict

Common claim (some made by this page before October 2026)	What the text says
Intentional radiators are tested to "ANSI C63.10", any edition	Only ANSI C63.10-2020 since October 30, 2025 (15.31(a)(3), 15.37(s)); C63.10a-2024 is not incorporated
Class A limits are "typically 10 dB" looser than Class B	15.107 gives 10 to 23 dB depending on frequency and detector; radiated Class A is at 10 m, not 3 m
Above 960 MHz the 500 μV/m limit is a peak limit, with 500/√2 μV/m average above 1 GHz	15.35(b): above 1000 MHz the limit is average-detector based, with a peak limit 20 dB higher
FCC limits are at 3 m and CISPR limits at 10 m	FCC Class A is at 10 m; CISPR 32 prints both 10 m and 3 m limits
DFS threshold is -62 dBm for any device below 200 mW	-62 dBm needs both EIRP below 200 mW and PSD below 10 dBm/MHz; otherwise -64 dBm (15.407(h)(2))
FCC cellular tests follow 3GPP TS 36.521, TS 38.521 and TS 51.010, including EVM	Part 2 lists power, modulation, occupied bandwidth, spurious and frequency stability (2.1046 to 2.1057); 3GPP suites are industry certification
SAR testing is mandatory for every device used within 20 cm	Sources at or below 1 mW, or below the 1.1307(b)(3) thresholds, are exempt from evaluation, though an RF exposure exhibit is still filed
Labs need "FCC accreditation", or A2LA or ILAC equivalence	ISO/IEC 17025 accreditation by an OET-recognized body plus FCC recognition (2.948(a), (e)); foreign labs through an MRA or 2.949 (2.948(f))
Cost and lead-time ranges per test campaign	No FCC text sets them; lab and TCB prices are commercial (2.962(e) for TCB fees)