The more elaborate broadcaster may follow applicable rules such as 15.221 for Carrier Current installations, which utilize a buildings existing wire system and/or power lines, but most opt for the simpler stand alone installation with a single whip or wire antenna.
- Following Rule 15.229 for FM is excellent if your objective is to cover your house and yard.
- Equally sufficient for covering your home area is 15.209 for AM.
- But if your objective is to reach your whole neighborhood and possibly beyond, then following rule 15.219 for AM is the only capable option (other than CC).
But where did these particular rules of Part 15 originate?
It's a rather important question because had not these particular subsets been provided by the FCC, we would not be able to legally broadcast without a license over the public airwaves at all without a license.
A long time ago I had asked the question: "Why, and when did 15.219 originate?" over in the Radio Discussions "LPFM and Community" forum, which is the remnant, or rather, a attempted revival of its previous incarnation "Community Radio USA", which was in it's day the most predominate and active Part 15 resource on the web.
My question was specifically in regard to a 2005 NOUO in which a AM1000 Rangemaster transmitter had been cited with 15.209, yet 15.219 had not even been mentioned. This cause me to speculate if perhaps 15.219 had not yet been in existence in at the time of the citation in 2005.. But it had been in existence.. So then why hadn't the NOUO considered the alternative .219 rule?
The question was eventually answered by member named Neil who explained:
It's an accurate answer, however, it doesn't account for the fact that in most cases NOUO's for AM always cite both rules and detail how neither compliance had been met. It appears to actually be a requirement that FCC inspecting agents consider both rules (based on the feud agents manual). But on rare occasion 15.219 does not get addressed for whatever reason, such occurrences are perhaps just due to the inspecting agent forgetting to include it in his report.
John Reed of the FCC seems to have addressed this in the following quoted comment:
"A transmitter is certified under Section 15.209 or 15.219. If it was certified under Section 15.209, the radiated emissions must comply with the limits in that section. If it was certified under Section 15.219, the input power and the combined lengths of the antenna, connecting cable and ground must comply with the limits in that section.
There is no need to check for compliance under Section 15.209 when the transmitter was certified under Section 15.219. If the 15.219 system exceeds the standards in that section, it is in violation of the rules.
Of course, if the 15.219 system exceeds those specifications the radiated emissions also will exceed the 15.209 limits. The field inspection folks may check for both simply to show that the system is not compliant under any of the possible standards." -John Reed
In Neil's research, he had deduced a feasible possibility of the origins of Part 15 broadcasting from bits and pieces puzzled together over the span of the years, and suggested a reasonable possibility of how it was Part 15 had originally came into existence, and voiced it to the community....
"..The best I have been able to piece together is that following the "Communication Act of 1934" is that in 1937 the rules were amended to allow for what we now know as Part 15 for AM. The intent, as I understand it, was to allow for the use of "phono oscillators" whereby the very expensive audio amplifiers and speakers already used for ratio reception could serve double duty by not only providing for off the air material but also for folks to play their own records through their existing radios..
|Phono oscillators were the first part 15 type devices.|
Used to broadcast from record player to a nearby radio
Neil also had some intriguing theories (not included here) on why the specific 100mw input measurement was implemented, which might have had to do with the actual operating components, voltage and temperatures of the fore mentioned phono-occilators. Neil's proposal, even to an non-technical minded person as myself makes reasonable sense. You can read about in the mist of discussion in the linked thread. But for the sake of getting staying on track, we're going to take a look at what Ermi was discovering...
It is true that, as we learned from Neil, that, in the 1930s, the FCC originally intended Part 15 AM for phono oscillators inside the home. However, Part 15.221, which is intended for outdoor use that is something like community broadcasting, was not adopted until 1990. The FCC uses impractically low field strength limits for 15.221. ..
|LBP provided the Part 15 carrier current system at Disney World|
Ermi, who also was turning up only bits and pieces, sought to track down more specifics about, amongst other things, the story behind the .219 rule, and eventually delved into official channels of communications with the FCC and succeeded in receiving an official response from John A. Reed, the Senior Engineer in the FCC Office of Engineering and Technology, Technical Rules Branch. Ermi was surprised by the wealth of information which had been provided...
"...The only question I asked the FCC was: When did they first enact the rules that are presently in Section 15.219? I was pleased when I received much more than what I asked for. John Reed told me the complete history of the rules governing unlicensed transmitting on the AM broadcast band. He provided a valuable service to the Part 15 AM community by explaining the intent of the rules and showing that the intent had not changed at all since they were first established in 1938..." -Ermi Roos Post #42
Ermi had basically received the entire story of Part 15, and in-turn presented it to us (in post #40), as explained verbatim from the corresponded response of John Reed (shown below)..
Beginning in 1938 as Rule 25.02, and ended with our present day Rules 15.209 and 15.219.
This is how all of our Part 15 stations came to be.
Below is a copy of John Reeds response in it's entirety. The BOLD CAPITALS inserts and paragraph breaks are mine, and not from the actual letter. I've included this to emphasize key points and make it easier to follow the history provided. Other than that, all info is exactly as stated, and in the sequence as John Reed presented it.
FROM THE DESK OF JOHN A. REED, SENIOR FCC ENGINEER, TECHNICAL RULES BRANCH:
OUR ORIGINAL PART 15 RULE:
"The original regulation, Rule 25.02, adopted November 21, 1938, (and currently stated only in Section 15.221(a)) permitted any operation on any frequency provided the field strength did not exceed 15 uV/m at a distance of Lambda/ 2 Pi.
RENUMBERINGS OF THE RULE:
Sometime after July 1, 1939, and before October 27 , 1939, this rule was renumbered Rule 2.102.
On July 21, 1948, in FCC 48-1837, this rule was again redesignated as Section 15.02.
On December 21, 1955, in Docked No. 9288, this rule was again redesignated as Section 15.7.
FIRST MAJOR RULE MODIFICATION:
ALTERNATE PROVISION FOR UNLICENSED OPERATION PROVIDED:
"On July 18, 1957, in Docket No. 9288, the Commission provided specific provisions for unlicensed operation in the AM band in what would be designated as Sections 15.202, and 15.204 of its regulations.
Section 15.202 stated that the field strength limits shall not exceed 24000[/f(kHz)] uV/m at a distance of 100 feet.
Section 15.204 was adopted as an alternative to the field strength limit to avoid the difficulties in making field strength measurements, provided that the input power to the final stage did not exceed 100 mW and the combined length of the antenna plus connecting lead did not exceed 10 feet.
PROPOSED 200 MILLIWATT INPUT:
While the Commission originally proposed to permit an input power of 200 mW in the AM band (3rd Notice of Proposed Rule Making in Docket 9288 adopted November 8,
1956), the adopted limit was reduced to 100 mW to reduce the potential area of interference.
SECOND MAJOR RULE MODIFICATION:
GROUND LEAD RESTRICTION:
"In an Order adopted on November 12, 1974 (FCC 74-1221), the rules were again modified, redesignating 15.202 as Section 15.111 and Section 15.204 as Section 15.113.
Section 15.113 was modified to include the length of the ground lead in addition to the length of the antenna and connecting lead in the 10 feet maximum. This change
was added because the earlier rules had not contemplated anyone using an extended ground plane [lead] to extend the range. The change was made to stop this practice.
UNEXPECTED RESULTS PROMPT A PROPOSAL FOR RULE CHANGE TO INSURE LIMITED RANGE: NO RULE CHANGE WAS ADOPTED:
"On April 14, 1976, in Docket No. 20780, the Commission proposed several changes in Sections 15.111 and 15.113, but did not adopt any of these changes. Paragraph 16, however, made the Commission's intentions clear that it implemented the alternative power measurements in lieu of a field strength limit to make it easier for home builders, that didn't have the means to perform field strength measurements, to demonstrate that their products complied with the standards. However, this rule was never intended to provide a greater operating range than the original field strength limit. The operating ranges were expected to be about equal, but improvements in efficiency were starting to result in increased range, and increased potential interference, for systems operating under Section 15.113.
RENUMBERING OF RULES TO THE CURRENT 15.209 and 15.219:
"Finally, on March 30, 1989, in ET Docket 87-389, the Commission adopted the current regulations. Section 15.111 was incorporated into Section 15.209 without changing the radiated emission limits except to specify the measurement range as 30 meters instead of 100 feet. Section 15.113 was redesignated as Section 15.219 with the only change to the limit being to specify the combined length of the antenna, connection lead and ground lead as 3 meters instead of 10 feet.
CREATION OF RULES FOR EDUCATIONAL CAMPUS BRODCASTING
Also in this order, the Commission established Section 15.221 to permit unlicensed operation in the AM broadcast band on the campus of any educational institute provided the emissions do not exceed the limits in 15.209 as measured from the campus boundary. On November 26, 1990, again in ET Docket No. 87-389, the Commission modified section 15.221 to permit carrier current systems to operate under the older limit of 15 uV/m at Lambda/2 Pi as an alternative to the field strength limits in Section 15.209.
That's the basic history. Let me know if you have any further questions.
The day we almost lost the benefits of 15.219
It should be closely noted that the regulation which is now our 15.219, underwent the amended change in 1974 to include the ground lead in the 100ft/3meter rule, specifically with the objective to completely insure that only a very limited range was achievable.. and when the FCC realized that even without that radiating ground lead, 15.219 was still very capable of exceeding the imposed limitations as of that in .209..
It was at this point in 1976 that the FCC had came very close to amending the 15.219 rule for the second time, with an even further limit imposed in .219, so to finally put a stop to extended range capability altogether...
Why they ultimately chose not amend the rule is unclear, but it is certain that if they had, most of our part 15 stations would more likely be broadcasting to the next room, and not the entire neighborhood. I suspect they didn't change it perhaps as not to hinder it's other industry uses, but that's just speculation.
The point is: We're fortunate to have what we've got, because we never were intended to have it, not to the extent of which we received. Beneficial to us is that it's the actual rules and not the original intentions themselves that govern the legality of our installations.
Ermi commented the same, in his observation concerning the information provided by John Reed, which equally emphasize how fortunate we really are that the proposed rule change in 1976 was never adopted, we got lucky, which is something which should be considered before anyone considers bending the rules or petitioning for greater Part 15 allowances as some have expressed..
"..The original rule had a field strength limit that was close to what is in Section 15.209 today. Section 15.209 appears to us to be very restrictive compared to 15.219, but the FCC's intent in establishing 15.219 was to provide a means for hobbyists, who are not likely to have access to a field strength meter, to demonstrate compliance with the original rule, which is similar to 15.209. The FCC did not intend for 15.219 to allow greater range than 15.209.."-Ermi Roos
So again, keep that in mind, and realize how lucky we are that the proposed changes to 15.219 in 1976 was not adopted, and run your stations in a respectable and legal manner, so not to incite possible reactions by the FCC to possibly again consider an amendment to this rule, which as it stands, provides us the ability of serving our local community on the public airwaves in a less limiting and reasonable capability.
By the way.. Don't you wish they had followed through with the original 200mw input proposal instead of the 100mw which it decided on?... sigh..
The elusive FCC 22 page document and it's relation to 15.219
NOUO Notices of Unlicensed Operation
Every NOUO in the AM band from Jan. 2011 thru Jan. 2014 (There were 7 of them).
Intended use of Part 15 in the eyes of the FCC
"..Moreover, regardless of strict adherence to the technical limitations in Part 15, a Low Power Communication Device is permitted to operate on a sufferance basis
only,.. ..The Commission never intended that Part 15 be used to establish a low power broadcast facility to service an entire community..."
The 200 Foot Elephant
The rule that's not a rule.
Part 15 Distiction and the Battle Against Piracy
FCC “Pirate” Advisory Flawed