FCC 15.35 Revised as of October 1, 2007
Goto Year:2006 |
2008
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) Unless otherwise specified, on any frequency or frequencies above 1000
MHz, the radiated emission limits are based on the use of measurement
instrumentation employing an average detector function. Unless otherwise
specified, measurements above 1000 MHz shall be performed using a minimum
resolution bandwidth of 1 MHz. When average radiated emission measurements
are specified in this part, including average emission measurements below
1000 MHz, there also is a limit on the peak level of the radio frequency
emissions. Unless otherwise specified, e.g. , see Sec. Sec. 15.250, 15.252, 15.255,
and 15.509–15.519, the limit on peak radio frequency emissions is 20 dB
above the maximum permitted average emission limit applicable to the
equipment under test. This peak limit applies to the total peak emission
level radiated by the device, e.g. , the total peak power level. Note that
the use of a pulse desensitization correction factor may be needed to
determine the total peak emission level. The instruction manual or
application note for the measurement instrument should be consulted for
determining pulse desensitization factors, as necessary.
(c) Unless otherwise specified, e.g. Sec. 15.255(b), when the radiated emission
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; 67 FR 34855 , May 16, 2002;
70 FR 6773 , Feb. 9, 2005]
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