🚀 go-pugleaf

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   Herb Poppe asks questions about FCC Part 15 standards:

   | 1) Is every "device" used in the home that contains a "computer" (micro-
   | processor, microcontroller, etc.) consider a "Class B computing device"?
   | Is that fancy microwave oven, washing machine or toaster(?) containing
   | a single-chip micro have to be certified by the FCC?  If not, what are
   | the rules associated with allowing such devices to be exempted.

   Yes, those fancy home appliances that use microprocessors
   as  control  elements  are computing devices if they meet
   FCC's definition.

   FCC Part 15J (Technical Standards  for  Computing  Equip-
   ment) defines a COMPUTING DEVICE as any electronic device
   or system that generates and uses timing signals or  pul-
   ses  at  a  rate  in excess of 10,000 pulses (cycles) per
   seconds and uses digital techniques.

   A CLASS A device is a computing device that  is  marketed
   for use in a commercial, industrial, or business environ-
   ment.

   A CLASS B device is a computing device that  is  marketed
   for  use in a residential environment notwithstanding its
   use in commercial, business, and industrial environment.

   Class B standards for radiated are stricter than Class A.


   | 2) A micro is just a (relatively) high speed digital circuit. Certainly
   | other high speed digital circuits that are not "computers" also generate
   | RF energy that could interfere with radio/TV reception. If such circuits
   | appear in products used in the home must they be certified as Class B
   | computing devices? If so, what is considered "high"?

   The rules apply to end products and peripherals (I/O dev-
   ices), not to subassemblies and components.


TABLE 1.  FCC Part 15 Subpart J Limits  for  Radiated  Emis-
          sions

       _________________________________________________
      |                    |    Class A       Class B  |
      | Freq(MHz)   Dist(m)|  uV/m   uV/m   uV/m   uV/m|
      |____________________|___________________________|
      | 30-88          3   |  300    49.5   100     40 |
      | 88-216         3   |  500    54     150    150 |
      | 216-1000       3   |  700    56.9   200     46 |
      |                    |                           |
      | 30-88         30   |   30    29.5              |
      | 88-216        30   |   50    34                |
      | 216-1000      30   |   70    36.9              |
      |____________________|___________________________|



   If the device is connected to an AC power line,  it  must
   also meet FCC standards for conducted emissions.


TABLE 2.  FCC Part 15 Subpart J Limits for  Conducted  Emis-
          sions

                  __________________________
                 | Class   Freq(MHz)   uV  |
                 |_________________________|
                 | A       0.45-1.6    1000|
                 |         1.6-30      3000|
                 |                         |
                 | B       0.45          30|
                 |_________________________|




   | 3) How is the "hobbyist" affected by the rules? Can I "homebrew" a system
   | and be legal? If so, can I make systems for my friends?
   | Can I describe such a system in the hobby press and be
   | legal? If so, can I offer "kits" for the described project at cost? for a
   | profit?


   FCC rules don't specify what articles you  can  write  in
   the hobby press.  If you offer "kits" for sale, they must
   comply with the FCC Part 15.

   Keep in mind that even if a device complies with Part  15
   standards,  but  still  causes  harmful interference, the
   user may be required to stop operation.

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Bob Parnass,  Bell Telephone Laboratories - ihnp4!ihuxz!parnass - (312)979-5414