So I started thinking about carrier current again, and the "prohibitive cost" of the radio systems gear. The coupler itself is not priced too bad; 495.00 US - its the transmitter that is a real kick in the pants.
Which made me poke around a bit, and think "hey, I can get one of these things from greece at 6watts, pump that into the coupler, and have carrier current for under a grand."
As soon as I talk my wife out of the 500 bucks for the coupler, I'll test my idea 🙂
There is an electric storm starting here at the moment, so I hope I don't get blown away, but hold up on spending that $500 until you check the rules more closely.
I just spent 2-hours slowly reading through sections of Part 15, it seems that the subject of "carrier current" is covered in various ways and while we focus on 15.221, the main rule for doing AM broadcast on the electric lines, if you dig deeper there are other sections that are cross-referenced.
One thing very interesting to think about is "15.3, Definitions, (f) Carrier current system. A system, or part of a system, that transmits radio frequency energy by conduction over the electric power lines. A carrier current system can be designed such that the signals are received by conduction directly from connection to the electric power lines (unintentional radiator) or the signals are received over-the-air due to radiation of the radio frequency signals from the power lines (intentional radiators)."
The interesting fact there is that carrier current is both unintentional AND intentionally radiated, covered in Subparts B and C.
But here's my main point, and the one which may keep you from buying the Greek transmitter..... I am fairly certain that transmitters used for carrier current must be FCC "verified," something described in very hard to follow language, and does not even seem to allow "home made" transmitters, as is possible with the 3-meter antenna approach.
But to be sure, we need other experienced members to comment on this and let us know what is true and what is not true on this point.
ever since i started part 15 radio when i was 12 years old in 2007. i started the original KDSX which was known back then as carl street radio (kinda like e street radio or b street radio on satellite radio) and started as that on carrier current fm.
the carrier current fm transmitter i have always used were mp3 car transmitters real cheap you as can get, the antenna is inside the 12 volt hookup and the end of the inside antenna touching the tip of the 12 volt hookup and the transmitter and internal antenna is sent through the car ac to wall adapter, and couples and hooks up at the wall plugin under the studio desk and is sent through the power lines throught the neighborhood and several blocks around it (the blocks here are very short). serves about 40-120 households depending on the conditions outside and serves anywhere from 120-360 people inside the coverage area.
Not being much of a rule thumper I am somehwat lost right now trying to find definitions of language used in Part 15 regarding "authorized, verified, and in one place it says.. authorized by verification."
The Definitions section in Subpart A - General - does not give the definitions for either "authorized" or "verified" in connection with subjects of unintentional radiators and intentional radiators.
We have a good idea of what "certification" means, as that is often discussed here.
For transmitters used in carrier current applications, what "authorization" or "verification" is necessary?
I see in one part of the rules the reference is "authority to market a device." But I think the language also applies, at times, to "using" certain devices.
i started ... that on carrier current fm.
Just wondering -- explicitly which Part 15 rule permits carrier current FM transmission where the transmitter directly drives an a-c power line?
Although it has been years since I've seen an article on home brew Carrier Current transmitters, I have read several over the years.
So, at least way back then, it must have been permissable to use a home brew transmitter for Carrier Current operation.
In the early days of CC "broadcasting,"
at colleges and universities, students
(engineering and otherwise) would
sometimes build the transmitters.
No problem there, at least in the
old days. If the unit (homemade or
even a kit) is clean as far as
RF spectrum is involved - I can't
think of anything that could go
wrong signal wise. And I am always looking
for "weird glitches" in the rules.
That is - glitches that favor Part 15 or - just
the reverse - those that could limit what
we can do with RF power or whatever.
I'm not a lawyer or an engineer, but
that's my 2 cents.
Bruce, DOGRADIO
but it was way before the term neutral injection came about. At the time, I had no knowledge of that concept.
I had a 35 watt LPB transmitter feeding into a coupler on our outdoor electrical pole. In the house, and back yard, where the lines were, the station, on 1120, sounded like a local. A transformer on the east side of the back door stopped the signal completely. It was not listenable in the driveway - which is long, but still..barely audible on the north side of the house.
Nevertheless I ran that thing 5 years before letting a "camp radio station" have the LPB system. Coupler is still on the pole, although I haven't used it since 1996.
Overall I was disappointed with carrier current. Earlier this year I asked Dan Braverman of Radio Systems about the pros and cons of their carrier current system vs the iAM with the ATU, and his response indicated that for most folks, the iAM would be ideal and less expensive. I still want one of those!
Many lawyers aren't lawyers.
What I mean by that is, many lawyers don't practice the kind of law you ask them about, and they don't know the answer.
Lawyers specialize, and I run into this in conversations with my corporate lawyer. He can't answer questions about broadcast law, copyright law or patent law.
What you've got to have is a team of lawyers, budget not with standing.
I actually play a lawyer on radio, named Stag Pinstripe, of the law firm Pinstripe, Stripmine and Shaft. In that role I can answer many of your questions, but for the drinking.
What happened to "The Last
Minute Radio Theater?" That was
one of the funniest things I ever
heard you do. Genius, really.
Sorry to depart from the subject.
I will keep this short.
Bruce, DOGRADIO
Bruce, you are every bit as great as you are, and have once again influenced the future.
Carl has been working on LPH#79, and now for sure he will include another Last Minute Radio Theatre. I have several written.
This is already fun and hasn't even begun.
Carl
Awsome!
Bruce, DOGRADIO
...So, at least way back then, it must have been permissable to use a home brew transmitter for Carrier Current operation.
The FCC added authorization under Part 15 for unlicensed operators to use a carrier-current system in the AM broadcast band on a legitimate educational campus, under certain conditions.
Could anyone quote FCC Part 15 sections/paragraphs permitting such unlicensed operations in the FM broadcast band?
http://www.gpo.gov/fdsys/pkg/CFR-2008-title47-vol1/content-detail.html
That's the entire "Title 47 - Telecommunication" rules spanning Parts 0 - 301. Our favorite Part 15 is only one of 302 "Parts"!
Drill down to Chapter I, Subchapter A, Part 2, Subpart J for the definitions of autorization, certification, verifican.
Happy reading! Cancel your book club membership and tear up your library card. This will keep you busy reading for years.
Thank you PhilB for the link to everything, and I will sit here for years browsing around.
Rich, although almost always right about everything you post, the carrier current rule is not strictly limited to colleges.
The section Part 15.221 is quite muddied up by ALSO including a provision for special campus regulation in the case of intentional radiation transmission, but the carrier current portion is not restricted to campuses.