Why, and when did 15.219 originate

[R. Fry]

...There are numeous newspaper articles quoting this guy about being compliant and not wanting to run afoul with the FCC rules.  BTW, this is a FM not a Part 15 AM. Sheesh...

Your comments were directed at one operator/FCC field office.

Mine were not.

[Ermi Roos]

If you live in Oregon, you have nothing better to do than go after Ken Cartwright, I suppose. The N.W. has its own enforcement problems. Lately, there have been a lot of transmitters popping up in Oregon and Washington on 1710 kHz, all broadcasting in the same foreign language (I won't say which language in order not to imply criticism of any nationality). Regardless of where the district office is, the enforcement should be done in an even-handed manner.

[R. Fry]

For Perspective, and Quoted Without Comment

RE: 1710 frequency

Published on another website on October 23, 2009 - 07:48 by someone other than R. Fry:

Mainly for (name redacted), but others please chime in.

The 1710 frequency is available on virtually all modern car radios, and it is dead clear in my area, sounds the same night or day, very quiet, nothing there.

It would be perfect, but the problem is that under Part 15, you must attenuate your signal, which will kill the range, will it not? So, how do you get around this restriction at the (location redacted) station?

Response to the above post, submitted by (responder's name redacted) on October 23, 2009 - 14:33.

I run 100 mW and I don’t worry about it. The Rangemaster I use is certified at 1710. The FCC is 30 miles south of here. One FCC agent's opinion is, the certified transmitter is compliant and splitting hairs over 50KHZ with no interference complaint, is a total waste of his time, given the amount of FM pirate activity here in Florida. Your mileage may vary. :-)

[druidhillsradio]

Response to the above post, submitted by (responder's name redacted) on October 23, 2009 - 14:33.

I run 100 mW and I don’t worry about it. The Rangemaster I use is certified at 1710. The FCC is 30 miles south of here. One FCC agent's opinion is, the certified transmitter is compliant and splitting hairs over 50KHZ with no interference complaint, is a total waste of his time, given the amount of FM pirate activity here in Florida. Your mileage may vary. :-)


OK.  I wrote that I admit it.  But since reconsidered due to commitments with another Part 15 operation.  However the pirate activity comment still stands. The Miami and Tampa offices have a hands full situation chasing high power pirates all over the state.  High power meaning >25 mW on FM. 

[druidhillsradio]

Here is a predicted Longley-Rice plot of the 25 mW Wkid station in Clearwater.  Assuming 25 mW is what they are running, (might be less) a Comet 5/8 at 10 feet above ground, and a receiving antenna 1 meter above ground, (car radio).  Not taken into consideration, cable/connector loss.  The location is exactly where the station is located.

http://s1055.photobucket.com/albums/s510/qstradio/

The red is pretty much full quieting wuth the blue getting noisy.

[R. Fry]

It wouldn't matter what their transmitter output power, antenna gain or antenna height might be -- none of that is defined by FCC 15.239 for unlicensed operators/systems in the FM broadcast band.

Compliance with 15.239 requires that the maximum field intensity in any direction 3 meters from the transmit antenna cannot exceed 250 µV/m, period.  Many combinations of transmitter power and antenna gain could produce that field, although doing so with a transmitter applying ~25 mW to a matched, 5/8-wave antenna is not one of them.  That combination will far exceed 15.239.

One example of a compliant system would be a transmitter supplying about 11 nW (0.000 000 011 watts) to a matched, 1/2-wave dipole.

If the station shown in druidhillsradio's clip actually met Part 15.239, then the limit of its 10 µV/m signal that might be useful to average FM receivers over a line of sight, unobstructed path will be about 250 feet -- which is about the radius distance of the smallest coverage circle on that linked map.

NOUOs have been issued to unlicensed operators where it can be calculated that the non-compliant fields measured by the FCC were produced by powers of less than 25 mW radiated by a 1/2-wave dipole antenna.

[druidhillsradio]

My point is: Mr Fry, et al, there are tools out there to show "functional compliance" if and when a FCC agent comes knocking.

[pianoplayer88key]

Is it permissible on FM to use a directional antenna so the signal exceeds 250 µV/m in some azimuths and elevations (and is attenuated in others), so long as the 3D/spherical RMS/average value does not exceed 250 µV/m?  For example could you have 2,000 µV/m peak on a 30° beam, average 10 µV/m on the "back" 300° (leaving 30° for the transition from lobe to null), 40-60 dB attenuation at elevations greater than 15° (which pattern I'm guessing would still have an RMS below 250 µV/m) and be in compliance?  And if so, what about using multiple synchronized co-channel transmitters with directional antennas, each aimed in a different direction?
Or, if I wanted to cover my entire ~ 90 by 250 foot (1/2 acre) yard (conductivity "8" according to the M3 map but is probably actually a lot less although I don't have a way of measuring it) with a signal that indicates at least 89 to 94 dBµ on a Tecsun DSP PL-xxx using only the built-in antenna (or at least 72-88 dBµ on the 2nd harmonic even though that'd severely overload the fundamental), would I be better off using LW (under 15.217), MW (under 15.219) or SW (under 15.225)?

[R. Fry]

Is it permissible on FM to use a directional antenna so the signal exceeds 250 µV/m in some azimuths and elevations (and is attenuated in others), so long as the 3D/spherical RMS/average value does not exceed 250 µV/m?

It is permissible under FCC 15.239 to set up a compliant operation using a directional transmit antenna, as long as the field intensity measured 3 meters in every direction from it does not exceed 250 µV/m -- including the maximum field intensity radiated by that directional antenna. 

IOW, using a directional transmit antenna in compliance with FCC 15.239 does not allow radiating fields greater than 250 µV/m in some desired direction(s) 3 meters from the antenna, while reducing fields in other directions.

The FCC doesn't care about how little field is radiated, it cares about how much field is radiated.

Or, if I wanted to cover my entire ~ 90 by 250 foot (1/2 acre) yard ... would I be better off using LW (under 15.217), MW (under 15.219) or SW (under 15.225)?

Assuming that all of these choices are functionally compliant with current FCC Rules and enforcement actions, and without running the comparison numbers, that area easily could be covered by a MW operation under 15.219 -- which for a good installation could provide a groundwave field intensity of more than 0.5 mV/m in a circular area with a radius of 650 feet around the transmit antenna.

[Richard J Powers]

Good grief.. start a new topic about the subject. How does all this have to do with this thread?