Realizing that FCC measurement of Part 15 signals probably allow something akin to driving 5-miles over the speed limit, we have variously called this mystical number "fudge factor" or "gray area."
In fact the scientific word used in specifying a "range of laxness" is TOLERANCE.
Licensed stations are fortunate because their RF output tolerance is specified in the rules: they are "tolerated" up to 5% above authorized power.
Of course at the tiny signal levels of Part 15, ...5% wouldn't be too much, so there's probably a "sliding scale" that gives a wider allowance for deviation.
In Kentucky there is no tolerance for deviation, but perhaps the Part 15 rules might not be as strict as the Rule Keeper would have it.
And 5% toleration above authorized antenna length???
Rob Veld
Are we tlking AM or FM here? If FM will that could be from 250 uV/m to say 700 uV/M at 3 meters. But when you talk 4000 uV/M @ 3 meters that is a big sway.
Should i ask Kim Davis?
Heh, Never mind. She still has no clue.
RE: Reply #3 above
Are we talking AM or FM here? If FM will that could be from 250 uV/m to say 700 uV/M at 3 meters.
Note that for other things equal, a power increase of 5% from any transmitter will increase the received field at a given distance only by the square root of that power increase -- which is about 2.5%.
IOW, a field of 250 µV/m would increase only to 256 µV/m for that change in tx power, rather than (to say) 700 µV/m.
Back in my pre-part 15 days I spent time with a Christian woman who said, "If you don't let Jesus Christ into your heart you will die!"
I asked, "Are you threatening me?"
She replied, "I don't have to!."
Mr Blare - Please explain/justify what you posted in your Reply 6 above.
Maybe they have huge FM Radio stations in Heaven. As A kid about 5 I said "When I get to heaven I'll get ahold of a BIG transmitter and transmit back to Earth so people will know what it is like up there. Dad laughed at that idea. But then again what about spirit boxes? Has anyone actually received a FM signal from Heaven? Are there Progressive Rock stations up there?
TheLegacy I've actually been to heaven and it's smaller than expected and very much like a theme park.
Mr. Rich my Post # 6 follows the character Kim Davis referenced in Mr. Rock95seven's Post # 4 mentioning the religious fundamentalist elected woman in his state who refuses to fulfill the oath she swore to God to uphold the duties of her office, based on religious grounds. Self-conflicted.
My lady friend came from the same mold, although she was quite pleasant when she dropped the Bible and spent time being human, often visiting me at the radio station.
If you are concerned about how this all relates to Part 15 radio there are at least two justifications: many of our stations broadcast topical information as news or comment, and as far as government officials are concerned consider the FCC.
All of a sudden it strikes me... we have several skepticly themed and atheist radio stations... imagine if you will, a fundamentalist Christian FCC inspector!
Federal lightning bolts!
Ideally the lab that tested a device for part 15 compliance would have a calibrated meter. Ideally any 2 calibrated meters would read the same field strength for the same source. Ideally every transmitter off an assembly line would have the same field strength. Ideally the environment a FM transmitter is mounted in and the way it is connected to audio source and power would not change the maximum field it radiates. Ideally the meter an inspector uses would agree with the meter used to test the original device for part 15 compliance. For all those ideallies to be real a bunch of money would have had to be spent by people who probably did not spend it. The meter at the testing lab was calibrated at one point, but who knows how it was doing the day of the test. The transmitters coming off the assembly line could have small differences in inductance or capacitance on the output making the antenna more or less efficient. The meter the inspector uses could have had a hell of a ride and may have gotten bumped so it will read just wrong. Tolerance from the desired or expected value hopefully covers all the above.
Hot rodding a FM transmitter and hoping it is below 250uv/m@3m + FCC tolerance seems like a risky thing to do. The NOUO for 640.901 microvolts per meter (uV/m) at 3 meters seems to show the New York FCC office thinks they have 6 significant figures when they measure field strength.