Sec. 15.31  Measurement standards.

    (a) The following measurement procedures are used by the Commission 
to determine compliance with the technical requirements in this part. 
Except where noted, copies of these procedures are available from the 
Commission's current duplicating contractor whose name and address are 
available from the Commission's Consumer Assistance Office at 202-632-
7000.
    (1) FCC/OET MP-1: FCC Methods of Measurements for Determining 
Compliance of Radio Control and Security Alarm Devices and Associated 
Receivers. Note: This procedure may be used only for testing devices for 
which verification is obtained, or for which an application for 
equipment authorization is filed before June 1, 1995. For compliance 
testing of these devices after that date, see paragraph (a)(6) of this 
section.
    (2) FCC/OET MP-2: Measurement of UHF Noise Figures of TV Receivers.
    (3) FCC/OET MP-3: FCC Methods of Measurements of Output Signal 
Level, Output Terminal Conducted Spurious Emissions, Transfer Switch 
Characteristics, and Radio Noise Emissions from TV Interface Devices. 
Note: This procedure may be used only for testing devices for which 
verification is obtained, or for which an application for equipment 
authorization is filed before June 1, 1995. For compliance testing of 
these devices after that date, see paragraph (a)(6) of this section.
    (4) FCC/OET MP-4 (1987): FCC Procedure for Measuring RF Emissions 
from Computing Devices. Note: This procedure may be used only for 
testing digital devices for which verification is obtained, or for which 
an application for equipment authorization is filed before May 1, 1994. 
For compliance testing of digital devices on or after May 1, 1994, see 
paragraph (a)(6) of this section.
    (5) FCC/OET MP-9: FCC Procedure for Measuring Cable Television 
Switch Isolation. Note: This procedure may be used only for testing 
devices for which verification is obtained, or for which an application 
for equipment authorization is filed before June 1, 1995. For compliance 
testing of these devices after that date, see paragraph (a)(6) of this 
section.
    (6) Digital devices authorized by verification, Declaration of 
Conformity, or for which an application for equipment authorization is 
filed on or after May 1, 1994, and intentional and other unintentional 
radiators for which verification is obtained, or for which an 
application for equipment authorization is filed on or after June 1, 
1995 are to be measured for compliance using the following procedure 
excluding section 5.7, section 9 and section 14: American National 
Standards Institute (ANSI) C63.4-1992, entitled ``Methods of Measurement 
of Radio-Noise Emissions from Low-Voltage Electrical and Electronic 
Equipment in the Range of 9 kHz to 40 GHz,'' published by the Institute 
of Electrical and Electronic Engineers, Inc. on July 17, 1992 as 
document number SH15180. This incorporation by reference was approved by 
the Director of the Federal Register in accordance with 5 U.S.C. 552(a) 
and 1 CFR part 51. The Commission encourages the use of this procedure 
for testing digital devices, intentional radiators, and other 
unintentional radiators as soon as practical. Copies of ANSI C63.4-1992 
may be obtained from: IEEE Standards Department, 455 Hoes Lane, P.O. Box 
1331, Piscataway, NJ 08855-1331, telephone 1-800-678-4333. Copies of 
C63.4-1992 may be inspected during normal business hours at the 
following locations:
    (i) Federal Communications Commission, 2025 M Street, NW., Office of 
Engineering and Technology (Room 7317), Washington, DC 20554,

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    (ii) Federal Communications Commission Laboratory, 7435 Oakland 
Mills Road, Columbia, MD 21046, or
    (iii) Office of the Federal Register, 800 North Capitol Street, NW., 
suite 700, Washington, DC.

    Note: Digital devices tested to show compliance with the provisions 
of Secs. 15.107(e) and 15.109(g) must be tested following the ANSI C63.4 
procedure described in paragraph (a)(6) of this section.

    (b) All parties making compliance measurements on equipment subject 
to the requirements of this part are urged to use these measurement 
procedures. Any party using other procedures should ensure that such 
other procedures can be relied on to produce measurement results 
compatible with the FCC measurement procedures. The description of the 
measurement procedure used in testing the equipment for compliance and a 
list of the test equipment actually employed shall be made part of an 
application for certification or included with the data required to be 
retained by the party responsible for devices authorized pursuant to a 
Declaration of Conformity or devices subject to notification or 
verification.
    (c) For swept frequency equipment, measurements shall be made with 
the frequency sweep stopped at those frequencies chosen for the 
measurements to be reported.
    (d) Field strength measurements shall be made, to the extent 
possible, on an open field site. Test sites other than open field sites 
may be employed if they are properly calibrated so that the measurement 
results correspond to what would be obtained from an open field site. In 
the case of equipment for which measurements can be performed only at 
the installation site, such as perimeter protection systems, carrier 
current systems, and systems employing a ``leaky'' coaxial cable as an 
antenna, measurements for verification or for obtaining a grant of 
equipment authorizaton shall be performed at a minimum of three 
installations that can be demonstrated to be representative of typical 
installation sites.
    (e) For intentional radiators, measurements of the variation of the 
input power or the radiated signal level of the fundamental frequency 
component of the emission, as appropriate, shall be performed with the 
supply voltage varied between 85% and 115% of the nominal rated supply 
voltage. For battery operated equipment, the equipment tests shall be 
performed using a new battery.
    (f) To the extent practicable, the device under test shall be 
measured at the distance specified in the appropriate rule section. The 
distance specified corresponds to the horizontal distance between the 
measurement antenna and the closest point of the equipment under test, 
support equipment or interconnecting cables as determined by the 
boundary defined by an imaginary straight line periphery describing a 
simple geometric configuration enclosing the system containing the 
equipment under test. The equipment under test, support equipment and 
any interconnecting cables shall be included within this boundary.
    (1) At frequencies at or above 30 MHz, measurements may be performed 
at a distance other than that specified provided: Measurements are not 
made in the near field, and it can be demonstrated that the signal 
levels to be measured at the distance employed can be detected by the 
measurement equipment. Measurements shall not be performed at a distance 
greater than 30 meters unless it can be demonstrated that measurements 
at a distance of 30 meters or less are impractical. When performing 
measurements at a distance other than that specified, the results shall 
be extrapolated to the specified distance using one of the following 
formulas: For measurements above 30 MHz that are not performed in the 
near field, an inverse linear-distance extrapolation factor (20 dB/
decade); for measurements performed in the near field, an inverse 
linear-distance-squared extrapolation factor (40 dB/decade).
    (2) At frequencies below 30 MHz, measurements may be performed at a 
distance closer than that specified in the regulations; however, an 
attempt should be made to avoid making measurements in the near field. 
Pending the development of an appropriate measurement procedure for 
measurements performed below 30 MHz, when performing measurements at a 
closer distance than specified, the results shall

[[Page 622]]

be extrapolated to the specified distance by either making measurements 
at a minimum of two distances on at least one radial to determine the 
proper extrapolation factor or by using the square of an inverse linear 
distance extrapolation factor (40 dB/decade).
    (3) The applicant for a grant of certification shall specify the 
extrapolation method used in the application filed with the Commission. 
For equipment subject to notification or verification, this information 
shall be retained with the measurement data.
    (4) When measurement distances of 30 meters or less are specified in 
the regulations, the Commission will test the equipment at the distance 
specified unless measurement at that distance results in measurements 
being performed in the near field. When measurement distances of greater 
than 30 meters are specified in the regulations, the Commission will 
test the equipment at a closer distance, usually 30 meters, 
extrapolating the measured field strength to the specified distance 
using the methods shown in this section.
    (5) Measurements shall be performed at a sufficient number of 
radials around the equipment under test to determine the radial at which 
the field strength values of the radiated emissions are maximized. The 
maximum field strength at the frequency being measured shall be reported 
in an application for certification.
    (g) Equipment under test shall be adjusted, using those controls 
that are readily accessible to or are intended to be accessible to the 
consumer, in such a manner as to maximize the level of the emissions. 
For those devices to which wire leads may be attached by the consumer, 
tests shall be performed with wire leads attached. The wire leads shall 
be of the length to be used with the equipment if that length is known. 
Otherwise, wire leads one meter in length shall be attached to the 
equipment. Longer wire leads may be employed if necessary to 
interconnect to associated peripherals.
    (h) For a composite system that incorporates devices contained 
either in a single enclosure or in separate enclosures connected by wire 
or cable, testing for compliance with the standards in this part shall 
be performed with all of the devices in the system functioning. If an 
intentional radiator incorporates more than one antenna or other 
radiating source and these radiating sources are designed to emit at the 
same time, measurements of conducted and radiated emissions shall be 
performed with all radiating sources that are to be employed emitting. A 
device which incorporates a carrier current system shall be tested as if 
the carrier current system were incorporated in a separate device; that 
is, the device shall be tested for compliance with whatever rules would 
apply to the device were the carrier current system not incorporated, 
and the carrier current system shall be tested for compliance with the 
rules applicable to carrier current systems.
    (i) If the device under test provides for the connection of external 
accessories, including external electrical input signals, the device 
shall be tested with the accessories attached. The device under test 
shall be fully exercised with these external accessories. The emission 
tests shall be performed with the device and accessories configured in a 
manner that tends to produce maximized emissions within the range of 
variations that can be expected under normal operating conditions. In 
the case of multiple accessory external ports, an external accessory 
shall be connected to one of each type of port. Only one test using 
peripherals or external accessories that are representative of the 
devices that will be employed with the equipment under test is required. 
All possible equipment combinations do not need to be tested. The 
accessories or peripherals connected to the device being tested shall be 
unmodified, commercially available equipment.
    (j) If the equipment under test consists of a central control unit 
and an external or internal accessory(ies) (peripheral) and the party 
verifying the equipment or applying for a grant of equipment 
authorization manufactures or assembles the central control unit and at 
least one of the accessory devices that can be used with that control 
unit, testing of the control unit and/or the accessory(ies) must be 
performed using the devices manufactured or assembled by that party, in 
addition

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to any other needed devices which the party does not manufacture or 
assemble. If the party verifying the equipment or applying for a grant 
of equipment authorization does not manufacture or assemble the central 
control unit and at least one of the accessory devices that can be used 
with that control unit or the party can demonstrate that the central 
control unit or accessory(ies) normally would be marketed or used with 
equipment from a different entity, testing of the central control unit 
and/or the accessory(ies) must be performed using the specific 
combination of equipment which is intended to be marketed or used 
together. Only one test using peripherals or accessories that are 
representatve of the devices that will be employed with the equipment 
under test is required. All possible equipment combinations are not 
required to be tested. The accessories or peripherals connected to the 
device being tested shall be unmodified, commercially available 
equipment.
    (k) A composite system is a system that incorporates different 
devices contained either in a single enclosure or in separate enclosures 
connected by wire or cable. If the individual devices in a composite 
system are subject to different technical standards, each such device 
must comply with its specific standards. In no event may the measured 
emissions of the composite system exceed the highest level permitted for 
an individual component. For digital devices which consist of a 
combination of Class A and Class B devices, the total combination of 
which results in a Class A digital device, it is only necessary to 
demonstrate that the equipment combination complies with the limits for 
a Class A device. This equipment combination may not be employed for 
obtaining a grant of equipment authorization or verifying a Class B 
digital device. However, if the digital device combination consists of a 
Class B central control unit, e.g., a personal computer, and a Class A 
internal peripheral(s), it must be demonstrated that the Class B central 
control unit continues to comply with the limits for a Class B digital 
device with the Class A internal peripheral(s) installed but not active.
    (l) Measurements of radio frequency emissions conducted to the 
public utility power lines shall be performed using a 50 ohm/50 uH line-
impedance stabilization network (LISN).

    Note: Receivers tested under the transition provisions contained in 
Sec. 15.37 may be tested with a 50 ohm/5 H LISN.

    (m) Measurements on intentional radiators or receivers, other than 
TV broadcast receivers, shall be performed and, if required, reported 
for each band in which the device can be operated with the device 
operating at the number of frequencies in each band specified in the 
following table:

                                                                        
------------------------------------------------------------------------
 Frequency range over which device    Number of    Location in the range
              operates               frequencies       of operation     
------------------------------------------------------------------------
1 MHz or less......................           1   Middle.               
1 to 10 MHz........................           2   1 near top and 1 near 
                                                   bottom.              
More than 10 MHz...................           3   1 near top, 1 near    
                                                   middle and 1 near    
                                                   bottom.              
------------------------------------------------------------------------

    (n) Measurements on TV broadcast receivers shall be performed with 
the receiver tuned to each VHF frequency and also shall include the 
following oscillator frequencies: 520, 550, 600, 650, 700, 750, 800, 
850, 900 and 931 MHz. If measurements cannot be made on one or more of 
the latter UHF frequencies because of the presence of signals from 
licensed radio stations or for other reasons to be detailed in the 
measurement report, measurements shall be made with the receiver 
oscillator at a nearby frequency. If the receiver is not capable of 
receiving channels above 806 MHz, the measurements employing the 
oscillator frequencies 900 and 931 MHz may be omitted.
    (o) The amplitude of spurious emissions from intentional radiators 
and emissions from unintentional radiators which are attenuated more 
than 20 dB below the permissible value need not be reported unless 
specifically required elsewhere in this part.
    (p) In those cases where the provisions in this section conflict 
with the measurement procedures in paragraph (a) of this section and the 
procedures were implemented after June 23, 1989,

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the provisions contained in the measurement procedures shall take 
precedence.
[ 54 FR 17714 , Apr. 25, 1989, as amended at  56 FR 13083 , Mar. 29, 1991; 
 57 FR 24990 , June 12, 1992;  57 FR 33448 , July 29, 1992;  58 FR 37430 , 
July 12, 1993;  58 FR 51249 , Oct. 1, 1993;  61 FR 14502 , Apr. 2, 1996;  62 FR 41881 , Aug. 4, 1997;  62 FR 45333 , Aug. 27, 1997]