From: ornitz@kodak.kodak.com (Barry Ornitz)
Subject: Re: "Part 15"
Originator: wdp@gagme
Organization: Eastman Kodak Company, Eastman Chemical Company Research Labs
Date: Mon, 24 Aug 1992 22:44:48 GMT

In article <1992Aug20.220649.28684@gagme.chi.il.us> yag@eng.umd.edu 
(Eric Funk) writes:
>Does anyone know where the infamous "Part 15" of FCC rules and regs can be
>found? 

All of the FCC Rules and Regulations may be found in Title 47 of the Code of
Federal Regulations (47 CFR).  Most good libraries should carry this.  You can
also order copies of the FCC rules from the Superintendent of Documents, 
Government Printing Office.

>Part 15 describes rules regarding unlicensed, low power emissions. It
>allows operation of ``Mr. Microphone'' as well as wireless telephones etc.
>I understand that FM broadcast band emissions were recently included. I also
>believe the 100 mW power limit is on INPUT power to the final stage RF amp.
>Can anyone verify this?

Part 15 covers both intentional and unintentional radiating devices and 
unlicensed transmission.  Specific broadcast devices for the FM broadcast
band have been included in Part 15 rules for perhaps thirty years or more.

The 100 milliwatt power limit for Part 15 broadcast in the 88-108 MHz band is
a MYTH.  At one time this was true, but I beleive it was in the early 1960's.
My earliest copy of the FCC rules for Part 15 is 1981.  At that time the
standards specified a maximum field strength of 50 microvolts per meter
measured at a distance of 15 meters from the device.  The current rules
specify a maximum field strength of 250 microvolts per meter at a distance of
three meters, a much more restrictive limit.

> I am specifically interested in starting a low power unlicensed station, and
>am wondering if there are any rules governing program content or modulation
>mode (ie  is music officially allowed, is SSB modulation allowed). 

Do not expect much range if you remain legal.  I did the near field
calculations to determine how much power could be supplied to a simple
quarter-wave groundplane antenna and meet the Part 15 rules - the answer
was approximately 3 NANOWATTS.  This works out to slightly less than 1 
MILLIVOLT peak-to-peak to the transmitting antenna.  I am not aware of
specific rules governing program content.  No specific modulation modes
are required but emissions must be confined to a band 200 kHz centered on
the operating frequency and must lie wholly within the 88-108 MHz band.
The 3 nW power level is about 33 million times lower than the ancient 0.1 W
limit.  I think you can understand from this that the FCC is serious about
reducing interference.

>I've also heard that there is a longwave experimenter's band allowing up to
>2 Watts unlicensed emissions. I'm intent on keeping the operation legal.
>Hopefully I can use a good high gain antenna and efficient modulation method
>such as SSB to get a good range. Any help would be appreciated.

This band, 160 - 190 kHz, requires that the total input power to the final
radio frequency stage not exceed 1 watt.  The total length of the antenna,
transmission line, and ground lead may not exceed 15 meters.  A high gain
and efficient antenna is impossible!  Bandwidth considerations for antenna
impedance matching make the only realistic transmission mode CW (Morse Code),
or perhaps some very slow on-off digital modes.

I hope you are sincere about the wish to remain legal.  You should read the
article "Radio Frequency Interference from Non-Licensed Devices" by Robert
Weller of the FCC in the August 1992 issue of RF Design magazine.  Fines for
illegal operation now start at the $7000 level according to Weller [FCC Policy
Statement, "In the Matter of Standards for Assessing Forfeitures", adopted
July 11, 1991 (FCC 91-217)].  Some of the FM broadcasting kits on the market
today do NOT meet the Part 15 standards; unfortunately it is YOU not the kit
manufacturer who gets fined.

Your best bet for any significant range (and it will still be small) is the
AM broadcast band where higher power levels are allowed.  You can also operate
in the 1600 to 1705 kHz region to avoid most of the interference.  You really 
need to consult the full FCC rules and regulations before you go further.  If 
your library does not carry 47 CFR, ask them to order a copy.  You might also 
check with any attorney who handles Federal cases for the CFR.

Questions about Part 15 unlicensed broadcasting seem to be growing lately on
the net.  Unfortunately misconceptions abound.  Perhaps a FAQ should be
developed on this.
				73, Barry
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|  ___  ________  |       Dr. Barry L. Ornitz          WA4VZQ
| |  / /        | |       Eastman Kodak Company
| | / /         | |       Eastman Chemical Company Research Laboratories
| |< < K O D A K| |       Process Instrumentation Research Laboratory
| | \ \         | |       P. O. Box 1972, Building 167B
| |__\ \________| |       Kingsport, TN  37662       615/229-4904
|                 |       INTERNET:   ornitz@kodak.com
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