Total posts : 45366
Actually, if you take a look at one of Rich’s graphs, it is likely that the Decade CM10 Tim received was Canadian tuned – depending on the height of the transmitting antenna, the field strength at 30 meters would be somewhere between 97 to 140+ (I can’t remember exactly, somewhere between 140-150uv) / m.
But the problem with measuring FM compliance with field strength is that field strength varies greatly depending on a number of factors, such as height of the transmitting antenna, height of the receiving antenna, never mind obstructions.
So a transmitter could be (Canadian) compliant at one height, but way over (by 50% according to Rich’s graph) at another height. And yet it’s still certified. And the typical end user has no way to tell.
In those new rules being proposed by the FCC for wireless microphones, they talk mainly about watts, not field strength. That would be the way to go for Part 15 FM – I doubt they would ever allow even 1 milliwatt, but perhaps 1 micro watt to the antenna? The Canadian standard specifically states under 1 microwatt, in addition to the field strength requirement.