Goto Section: 15.229 | 15.233 | Table of Contents
FCC 15.231
Revised as of October 2, 2015
Goto Year:2014 |
2016
§ 15.231 Periodic operation in the band 40.66-40.70 MHz and above 70 MHz.
(a) The provisions of this section are restricted to periodic operation
within the band 40.66-40.70 MHz and above 70 MHz. Except as shown in
paragraph (e) of this section, the intentional radiator is restricted to the
transmission of a control signal such as those used with alarm systems, door
openers, remote switches, etc. Continuous transmissions, voice, video and
the radio control of toys are not permitted. Data is permitted to be sent
with a control signal. The following conditions shall be met to comply with
the provisions for this periodic operation:
(1) A manually operated transmitter shall employ a switch that will
automatically deactivate the transmitter within not more than 5 seconds of
being released.
(2) A transmitter activated automatically shall cease transmission within 5
seconds after activation.
(3) Periodic transmissions at regular predetermined intervals are not
permitted. However, polling or supervision transmissions, including data, to
determine system integrity of transmitters used in security or safety
applications are allowed if the total duration of transmissions does not
exceed more than two seconds per hour for each transmitter. There is no
limit on the number of individual transmissions, provided the total
transmission time does not exceed two seconds per hour.
(4) Intentional radiators which are employed for radio control purposes
during emergencies involving fire, security, and safety of life, when
activated to signal an alarm, may operate during the pendency of the alarm
condition
(5) Transmission of set-up information for security systems may exceed the
transmission duration limits in paragraphs (a)(1) and (a)(2) of this
section, provided such transmissions are under the control of a professional
installer and do not exceed ten seconds after a manually operated switch is
released or a transmitter is activated automatically. Such set-up
information may include data.
(b) In addition to the provisions of § 15.205, the field strength of
emissions from intentional radiators operated under this section shall not
exceed the following:
Fundamental frequency (MHz) Field strength of fundamental (microvolts/meter)
Field strength of spurious emissions (microvolts/meter)
40.66-40.70 2,250 225
70-130 1,250 125
130-174 ^11,250 to 3,750 ^1125 to 375
174-260 3,750 375
260-470 ^13,750 to 12,500 ^1375 to 1,250
Above 470 12,500 1,250
^1Linear interpolations.
(1) The above field strength limits are specified at a distance of 3 meters.
The tighter limits apply at the band edges.
(2) Intentional radiators operating under the provisions of this section
shall demonstrate compliance with the limits on the field strength of
emissions, as shown in the above table, based on the average value of the
measured emissions. As an alternative, compliance with the limits in the
above table may be based on the use of measurement instrumentation with a
CISPR quasi-peak detector. The specific method of measurement employed shall
be specified in the application for equipment authorization. If average
emission measurements are employed, the provisions in § 15.35 for averaging
pulsed emissions and for limiting peak emissions apply. Further, compliance
with the provisions of § 15.205 shall be demonstrated using the measurement
instrumentation specified in that section.
(3) The limits on the field strength of the spurious emissions in the above
table are based on the fundamental frequency of the intentional radiator.
Spurious emissions shall be attenuated to the average (or, alternatively,
CISPR quasi-peak) limits shown in this table or to the general limits shown
in § 15.209, whichever limit permits a higher field strength.
(c) The bandwidth of the emission shall be no wider than 0.25% of the center
frequency for devices operating above 70 MHz and below 900 MHz. For devices
operating above 900 MHz, the emission shall be no wider than 0.5% of the
center frequency. Bandwidth is determined at the points 20 dB down from the
modulated carrier.
(d) For devices operating within the frequency band 40.66-40.70 MHz, the
bandwidth of the emission shall be confined within the band edges and the
frequency tolerance of the carrier shall be ±0.01%. This frequency tolerance
shall be maintained for a temperature variation of −20 degrees to + 50
degrees C at normal supply voltage, and for a variation in the primary
supply voltage from 85% to 115% of the rated supply voltage at a temperature
of 20 degrees C. For battery operated equipment, the equipment tests shall
be performed using a new battery.
(e) Intentional radiators may operate at a periodic rate exceeding that
specified in paragraph (a) of this section and may be employed for any type
of operation, including operation prohibited in paragraph (a) of this
section, provided the intentional radiator complies with the provisions of
paragraphs (b) through (d) of this section, except the field strength table
in paragraph (b) of this section is replaced by the following:
Fundamental frequency (MHz) Field strength of fundamental (microvolts/meter)
Field strength of spurious emission (microvolts/meter)
40.66-40.70 1,000 100
70-130 500 50
130-174 500 to 1,500^1 50 to 150^1
174-260 1,500 150
260-470 1,500 to 5,000^1 150 to 500^1
Above 470 5,000 500
^1Linear interpolations.
In addition, devices operated under the provisions of this paragraph shall
be provided with a means for automatically limiting operation so that the
duration of each transmission shall not be greater than one second and the
silent period between transmissions shall be at least 30 times the duration
of the transmission but in no case less than 10 seconds.
[ 54 FR 17714 , Apr. 25, 1989; 54 FR 32340 , Aug. 7, 1989, as amended at 68 FR 68546 , Dec. 9, 2003; 69 FR 71383 , Dec. 9, 2004]
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Goto Section: 15.229 | 15.233
Goto Year: 2014 |
2016
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