Chris, The rule that supersedes the others is: Don't interfere. However... there's a general perception that Class A is cheaper to build than Class B and not to ask for stricter standards if aiming at a better deal. This can result in specifying Class A limits if there is any justification at all for claiming non-residential operation. We do know that even Class B isn't good enough all the time, and Class A would not be better, but worse than that, but what I am looking for is some evidence that there is a de-facto standard applied by the regulatory authorities (in my case the FCC) to the introduction into or near a residential neighborhood of equipment only verified to meet Class A.
Cortland ====================== Original Message Follows ==================== >> Date: 25-Aug-97 13:20:16 MsgID: 1054-3884 ToID: 72146,373 From: Chris Dupres chris_dupres Subj: RE: Antenna Calibration/Site Attenuation Chrg: $0.00 Imp: Norm Sens: Std Receipt: No Parts: 1 Hi Cortland. You asked: <(As an aside, can anyone here say if the COmmission has ever specifically ruled on how far away from residences Class A equipment must be kept? > In my meanderings around the Compliance Biosphere, I've spoken to many enforcement people, competent bodies, even Government administrators. The general opinion seems to be 'If you meet the general intention of the Directives via the Standards, then the world will be a better trading place'. Note the deliberate absence of the word 'distance' and 'field strength, and 'interference'. In general, the advice I live with, and give, is that you shouldn't expect a TV to work perfectly on top of a Microwave cooker, and you wouldn't expect an electric pencil sharpener to reverse if you use a portable phone nearby. I feel that in any one typical domestic situation, the RF signature of a location is so far removed from an OATS or screened room as to be almost meaningless in practical terms, but you gotta put some rules down somewhere. I akin it to judging how fast a car can go by the shape of the hub caps. (They only put Hot Hub Caps on fast cars?) I had a case of a TIG welder interfering with a VHF radio some 200 metres away, awful wide band hash whenever the TIG fired up. I've also had Quadrupole Mass Spectrometers (pico and femto amps) behaving perfectly when 600mA 2kV Argon Arcs are being started in the same vacuum chamber. In answer to your question, I'm not aware of any requirements for distances between emitters and receptors, notwithstanding that there may be local by-laws which prohibit people camping beside arc furnaces, or something. In the UK, if you regularly get nuisance interference from anything at all, one can approach British Telecom, the monopoly holder, who will investigate and find the source of the intereference, and politely suggest to the source that they do something about it, but I'm not sure what teeth they have. The point is, is that they don't seem to take distance into account. It's all to do with the Wireless Telegraphy act, I think. That should be as clear as mud... Chris Dupres Surrey, UK. **Primary Recipient: Cortland Richmond 72146,373 ====================== End of Original Message =====================
