[Code of Federal Regulations]
[Title 47, Volume 1]
[Revised as of October 1, 2001]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR15.35]

[Page 683-684]
 
                       TITLE 47--TELECOMMUNICATION
 
              CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION
 
PART 15--RADIO FREQUENCY DEVICES--Table of Contents
 
                           Subpart A--General
 
Sec. 15.35  Measurement detector functions and bandwidths.

    The conducted and radiated emission limits shown in this part are 
based on the following, unless otherwise specified elsewhere in this 
part:
    (a) On any frequency or frequencies below or equal to 1000 MHz, the 
limits shown are based on measuring equipment employing a CISPR quasi-
peak detector function and related measurement bandwidths, unless 
otherwise specified. The specifications for the measuring instrument 
using the CISPR quasi-peak detector can be found in Publication 16 of 
the International Special Committee on Radio Interference (CISPR) of the 
International Electrotechnical Commission. As an alternative to CISPR 
quasi-peak measurements, the responsible party, at its option, may 
demonstrate compliance with the emission limits using measuring 
equipment employing a peak detector function, properly adjusted for such 
factors as pulse desensitization, as long as the same bandwidths as 
indicated for CISPR quasi-peak measurements are employed.

    Note: For pulse modulated devices with a pulse-repetition frequency 
of 20 Hz or less and for which CISPR quasi-peak measurements are 
specified, compliance with the regulations shall be demonstrated using 
measuring equipment employing a peak detector function, properly 
adjusted for such factors as pulse desensitization, using the same 
measurement bandwidths that are indicated for CISPR quasi-peak 
measurements.

    (b) On any frequency of frequencies above 1000 MHz, the radiated 
limits shown are based upon the use of measurement instrumentation 
employing an average detector function. When average radiated emission 
measurements are specified in the regulations, including emission 
measurements below 1000 MHz, there is also a limit on the radio 
frequency emissions, as measured using instrumentation with a peak 
detector function, corresponding to 20 dB above the maximum permitted 
average limit for the frequency being investigated unless a different 
peak emission limit is otherwise specified in the rules in this part, 
e.g., see Sec. 15.255. Unless otherwise specified, measurements above 
1000 MHz shall be performed using a minimum resolution bandwidth of 1 
MHz. Measurement of AC power line conducted emissions are performed 
using a CISPR quasi-peak detector, even for devices for which average 
radiated emission measurements are specified.
    (c) Unless otherwise specified, e.g. Sec. 15.255(b), when the 
radiated emission

[[Page 684]]

limits are expressed in terms of the average value of the emission, and 
pulsed operation is employed, the measurement field strength shall be 
determined by averaging over one complete pulse train, including 
blanking intervals, as long as the pulse train does not exceed 0.1 
seconds. As an alternative (provided the transmitter operates for longer 
than 0.1 seconds) or in cases where the pulse train exceeds 0.1 seconds, 
the measured field strength shall be determined from the average 
absolute voltage during a 0.1 second interval during which the field 
strength is at its maximum value. The exact method of calculating the 
average field strength shall be submitted with any application for 
certification or shall be retained in the measurement data file for 
equipment subject to notification or verification.

[54 FR 17714, Apr. 25, 1989, as amended at 56 FR 13083, Mar. 29, 1991; 
61 FR 14502, Apr. 2, 1996; 63 FR 42279, Aug. 7, 1998]