excerpts from FCC "Part 15" rules
(Title 47 of the Code of Federal Regulations, Part 15)


Subpart A -- General


15.1 Scope of this part.

(a) This part sets out the regulations under which an intentional,
unintentional, or incidental radiator may be operated without an
individual license.  It also contains the technical specifications,
administrative requirements and other conditions relating to the
marketing of part 15 devices.


15.5 General conditions of operation.

(b) Operation of an intentional, unintentional, or incidental radiator
is subject to the conditions that no harmful interference is caused
and that interference must be accepted that may be caused by the
operation of an authorized radio station, by another intentional or
unintentional radiator, by industrial, scientific and medical (ISM)
equipment, or by an incidental radiator.

(c) The operator of a radio frequency device shall be required to cease
operating the device upon notification by a Commission representative
that the device is causing harmful interference.  Operation shall not
resume until the condition causing the harmful interference has been
corrected.


15.23 Home-built devices.

(a) Equipment authorization is not required for devices that are not
marketed, are not constructed from a kit, and are built in quantities
of five or less for personal use.

(b) It is recognized that the individual builder of home-built equipment
may not possess the means to perform the measurements for determining
compliance with the regulations.  In this case, the builder is expected
to employ good engineering practices to meet the specified technical
standards to the greatest extent practicable.  The provisions of 15.5
apply to this equipment.


15.35 Measurement detector functions and bandwidths.

(b) ...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.


Subpart C -- Intentional Radiators


15.207 Conducted limits.

(a) For an intentional radiator which is designed to be connected to the
public utility (AC) power line, the radio frequency voltage that is
conducted back onto the AC power line on any frequency or frequencies
within the band 450 kHz to 30 MHz shall not exceed 250 microvolts.
Compliance with this provision shall be based on the measurement of
the radio frequency voltage between each power line and ground at the
power terminals.

(c) The limit shown in paragraph (a) of this section shall not apply
to carrier current systems operating as intentional radiators on
frequencies below 30 MHz.  In lieu thereof, these carrier current
systems shall be subject to the following standards:
 (1) For carrier current systems containing their fundamental emission
within the frequency band 535-1705 kHz and intended to be received
using a standard AM broadcast receiver: no limit on conducted emissions.
 (2) For all other carrier current systems: 1000 uV within the frequency
band 535-1705 kHz.


15.209 Radiated emission limits; general requirements.

(a) Except as provided elsewhere in this subpart, the emissions from
an intentional radiator shall not exceed the field strength levels
specified in the following table:

                 |   Field strength       |   Measurement distance
Frequency (MHz)  |   (microvolts/meter)   |   (meters)
-----------------+------------------------+-----------------------
0.009-0.490          2400/F(kHz)               300
0.490-1.705          24000/F(kHz)               30
1.705-30.0           30                         30
30-88**              100**                       3
88-216**             150**                       3
216-960              200**                       3
Above 960            500                         3
-----------------+------------------------+-----------------------

**Except as provided in paragraph (g), fundamental emissions from
intentional radiators operating under this Section shall not be
located in the frequency bands 54-72 MHz, 76-88 MHz, 174-216 MHz or
470-806 MHZ. 

  {Editor's note: paragraph (g) allows perimeter protection systems
  and biomedical telemetry devices to use the frequency bands 54-72 MHz, 
  76-88 MHz, 174-216 MHz or 470-806 MHZ.  These are TV broadcast channels.
  No other unlicensed transmissions on TV frequencies are permitted.}
  
  
15.215 Additional provisions to the general radiated emission limitations.

(a) The regulations in 15.217 through 15.251 provide alternatives to the
general radiated emission limits for intentional radiators operated in
specified frequency bands.  Unless otherwise stated, there are no
restrictions as to the types of operation permitted under these sections.


15.217 Operation in the band 160-190 kHz.

(a) The total input power to the final radio frequency stage (exclusive
of filament or heater power) shall not exceed one watt.

(b) The total length of the transmission line, antenna, and ground lead
(if used) shall not exceed 15 meters.

(c) All emissions below 160 kHz or above 190 kHz shall be attenuated at
least 20 dB below the level of the unmodulated carrier.  Determination
of compliance with the 20 dB attenuation specification may be based on
measurements at the intentional radiator's antenna output unless the
intentional radiator uses a permanently attached antenna, in which case
compliance shall be demonstrated by measuring the radiated emissions.


15.219 Operation in the band 510-1705 kHz.

(a) The total input power to the final radio frequency stage (exclusive of
filament or heater power) shall not exceed 100 milliwatts.

(b) The total length of the transmission line, antenna and ground lead
(if used) shall not exceed 3 meters.

(c) All emissions below 510 kHz or above 1705 kHz shall be attenuated at
least 20 dB below the level of the unmodulated carrier.  Determination
of compliance with the 20 dB attenuation specification may be based on
measurements at the intentional radiator's antenna output unless the
intentional radiator uses a permanently attached antenna, in which case
compliance shall be demonstrated by measuring the radiated emissions.


15.221 Operation in the band 525-1705 kHz.

(a) Carrier current systems and transmitters employing a leaky coaxial
cable as the radiating antenna may operate in the band 525-1705 kHz
provided the field strength levels of the radiated emissions do not
exceed 15 uV/m, as measured at a distance of 47.715/(frequency in kHz)
meters (equivalent to Lambda/2Pi) from the electric power line or the
coaxial cable, respectively.  The field strength levels of emissions
outside this band shall not exceed the general radiated emission limits
in 15.209.

(b) As an alternative to the provisions in paragraph (a) of this section,
intentional radiators used for the operation of an AM broadcast station
on a college or university campus or on the campus of any other
education institution may comply with the following:
 (1) On the campus, the field strength of emissions appearing outside
of this frequency band shall not exceed the general radiated emission
limits shown in 15.209 as measured from the radiating source.  There
is no limit on the field strength of emissions appearing within this
frequency band, except that the provisions of 15.5 continue to comply.
{Editor's note: they probably meant "continue to apply."}
 (2) At the perimeter of the campus, the field strength of any emissions,
including those within the frequency band 525-1705 kHz, shall not exceed
the general radiated emission in 15.209.
 (3) The conducted limits specified in 15.207 apply to the radio
frequency voltage on the public utility power lines outside of the
campus.  Due to the large number of radio frequency devices which may
be used on the campus, contributing to the conducted emissions, as an
alternative to measuring conducted emissions outside of the campus,
it is acceptable to demonstrate compliance with this provision by
measuring each individual intentional radiator employed in the system
at the point where it connects to the AC power lines.

(c) A grant of equipment authorization is not required for intentional
radiators operated under the provisions of this Section.  In lieu
thereof, the intentional radiator shall be verified for compliance with
the regulations in accordance with subpart J of part 2 of this chapter.
This data shall be kept on file at the location of the studio, office
or control room associated with the transmitting equipment.  In some
cases, this may correspond to the location of the transmitting equipment.

(d) For the band 535-1705 kHz, the frequency of operation shall be chosen
such that operation is not within the protected field strength contours
of licensed AM stations.


15.239 Operation in the band 88-108 MHz.

(a) Emissions from the intentional radiator shall be confined within a
band 200 kHz wide centered on the operating frequency.  The 200 kHz band
shall lie wholly within the frequency range of 88-108 MHz.

(b) The field strength of any emissions within the permitted 200 kHz
band shall not exceed 250 microvolts/meter at 3 meters.  The emission
limit in this paragraph is based on measurement instrumentation employing
an average detector.  The provisions in 15.35 for limiting peak emissions
apply.

(c) The field strength of any emissions radiated on any frequency outside
of the specified 200 kHz band shall not exceed the general radiated
emission limits in 15.209.