W1RFI
join:2003-05-12
Burlington, CT | reply to lerandell
Re: No faith in humanity? > For all we know the emitted RF could be -85 dB and
> require you to be 1 inch from the line to get
> interference.
If that were the case, would anyone be concerned about interference?
I realize this is an old thread, but I ran across is and wanted to respond to this one point.
The permitted levels on 30 MHz are 30 uV/m, 30 meters from the source. This will translate to extremely strong received noise levels, greater than S9 on receiver signal strength meters and several tens of dB greater than the other man-made noise in any environment. Above 30 MHz, the limits are 90 uV/m, 10 meters from the source, almost as strong, in what would otherwise be a quiet noise environment.
BPL emits at or near these levels across several to tens of MHz of spectrum, completely filling that spectrum, virtually all of the time and along significant lenghts of power line. ARRL tests have shown BPL to be strong along over a mile of power line, and at levels strong enough to cause interference for as much as 1000 feet away for mobile stations and 1 mile away for fixed stations with rotable gain antennas.
ARRL has not completely abandoned other services, having provided them with substantial information about the EMC aspects of BPL. In the long run, however, they do need to speak for themselves. Some have, to some extent. But ARRL does not have the standing to speak for them.
Last, one point. The "30-50" MHz systems actually use 32-48 MHz, from what I have seen, and the 10- and 6-meter Amateur bands are not affected.
Ed Hare, W1RFI@arrl.org
ARRL Lab |
