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here is a story of a project done during the 70’s by some colledge students using Carrier Current AM Transmitters.
maybe some one could take this idea and run with it.
Total posts : 45366Interesting that they were shut down by the FCC.
Total posts : 45366Agreed. I could not find any details about this in the links but I suspect it is because they bent the rules and went beyond a college campus with their carrier current system.
It is also interesting that they were able to use utility poles as transmitter mounts. Utilities do not want other non utilites using their poles and for good reasons.
Neil
Total posts : 45366Just think what you could do if you put a system on the 13KV lines. You really could cover an entire small town. I’d have to check the part 15 rules, but I don’t think carrier current is limited to a college campus. It is limited to a certain distance from the wires though. And it might be easy to exceed that distance. If you had a small power company you might be able to get permission to use the poles. Chances of find a small power company like this are now extremely rare.
Total posts : 45366Greg,
You are correct that the rules for carrier current are not exclusively for campus operations but it does appear that they are very restrictive regarding field strength. I have no idea why in the link above they were “shut down” and I can only speculate. For those who are interested, here are the pertenent rules revised Sept. 05:
[quote]
Section 15.221 Operation in the band 525 – 1705 kHz.
(a) Carrier current systems and transmitters employing a leaky coaxial cable as the radiating
antenna may operate in the band 525-1705 kHz provided the field strength levels of the radiated
emissions do not exceed 15 uV/m, as measured at a distance of 47,715/(frequency in kHz) meters
(equivalent to Lambda/2Pi) from the electric power line or the coaxial cable, respectively. The field
strength levels of emissions outside this band shall not exceed the general radiated emission limits in
Section 15.209.
(b) As an alternative to the provisions in paragraph (a), intentional radiators used for the
operation of an AM broadcast station on a college or university campus or on the campus of any other
education institution may comply with the following:
(1) On the campus, the field strength of emissions appearing outside of this frequency
band shall not exceed the general radiated emission limits shown in Section 15.209 as measured from the
radiating source. There is no limit on the field strength of emissions appearing within this frequency
band, except that the provisions of Section 15.5 continue to comply.
(2) At the perimeter of the campus, the field strength of any emissions, including those
within the frequency band 525 – 1705 kHz, shall not exceed the general radiated emissions in Section
15.209.
[/quote]The field strength of 15.209 is less than that produced (by virtue of the power and antenna restrictions) by 15.219 so it would seem that the 3 meter, 100 mW rules would allow better coverage except this is from essentially a point source where carrier current seems to be OK with a lower field strength but it can be spread along miles of wire. I don’t know of anyone who has done this other than on a campus and maybe someone will volunteer their experience. My city has installed underground concrete conduit and fiberoptic cables which they lease to anyone willing to pay. Maybe such conduits would be available for leaky coax, but again, I don’t know how this would work underground. Outdoor fiber optic cable has two “messenger” wires and perhaps they could be used for RF. Just brainstorming.
As far as tapping into the 13 kV lines, I can think of easier ways to achieve suicide. Also, the RF doesn’t get through the distribution transformers so this system would be back to the radiation limits mentioned above. It may work but I don’t think it is worth pursuing.
Here, there is one transformer for two houses. There is a 22 kV. 3 phase distribution trunk 4 feet underground in my front yard and I have to wonder if I could detect a RF signal if it was on this trunk. Fun to think about but not workable here.
A leaky coax system may work if one could get permission and bear the cost of installing the coax on the utility poles. Maybe I am thinking small but I would not even pursue it. Perhaps it makes more sense to stream on the internet?
Just some stuff to think about.
Neil
Total posts : 45366Have you looked at what RIAA wants to charge for your internet stream? If you had a popular commercial station the fees would be incredible.
The reason I thought about the higher 13KV or more lines is that they do not have as many transformers effecting them, so you get a longer run between transmitters. Not exactly a safe hook up, but a different twist to carrier current.
Just an aside… When I worked at one of the local TV stations, our power company put together a seminar aimed towards TV station live truck operators. It was pretty interesting. Even dry wooden ladders are no good against a 13kv line.
Total posts : 45366Greg wrote:
[quote]Have you looked at what RIAA wants to charge for your internet stream? If you had a popular commercial station the fees would be incredible.
[/quote]No, I haven’t, but it seems to me that if you had a popular commercial station, internet based, licensed or not, then the income should exceed the expenses. If not, then it is time to consider why you are doing this. Some do it for the hobby pleasure at no profit or even a loss and others expect to make money. You have to spend money to make money if that is your objective.
Considering the range limitations of legal unlicensed broadcasting it appears to me that the chances of an economically viable commercial unlicensed enterprise are slim. Read again the link in the original post here which describes an unlicensed operation which tried to be commercially successful as an example of what I am talking about. I don’t know why they failed but they did.
Some posters on this board report “successful” part 15 operations and perhaps they could offer some input other than links to very nicely designed websites which could explain their successes. Are any commercially successful? I know “them’s fightin’ words” but I would be interested in hearing about any financially self sustaining commercial (not supported by grants, donations, or hobbiest expenditures) unlicensed over the air stations.
Neil
Total posts : 45366[quote]Have you looked at what RIAA wants to charge for your internet stream?
—
No, I haven’t
[/quote]Many have argued that the RIAA fees were put in place to pretty much prevent streaming guild materials completely. The fees for internet streaming are really, really high for the audience size and operator revenue.
The best work-around seems to be using a third party clearing house, like the firms who sell streaming bandwidth and also license content.
Are there any profitable operations, Part 15 or streaming? Not that I’ve ever heard of. I think you’ll make more more money, and a much better ROI, on an espresso stand – plus, you could broadcast to your customers while they waited in your drive through 🙂
Come to think of it, I haven’t heard of that many profitable licensed AM stations these days either – even hot talk and Hispanic seem to do better on FM 🙂
Total posts : 45366I had talked to one of these guys a while back, and first off – this wasn’t a campus station: This was a commercial venture.
At the time they di this, there were a lot more FCC Field agents, and they were VERY tough on everyone.
They got permission from the town to do this (small town, definate/obvious benefit to the town), and worked hard to get the tiny trannys up and running and synched.
Carrier Current has to be within some field str from the power line (I forget exactly) – and they were within the limits except where the lines ran along the waterfront. The mindset was that they could up the power, because no one was going to measure from the oceanside. Ha.. guess they were wrong.
Now there has got to be more to this story than was published, even at the time I couldn’t see the FCC just popping in and closing them down without giving them an opportunity to fix the problem. So either someone at the FCC took a dislike to these guys (probable), or they founght “the man” (not as likely, but possible, since people usually boast these things), or some large station felt they were being infringed upon (most likely).
Nath, the assumptions are strictly that: Assumptions, and my own opinion.
Who knows?
I know that MLR ran a CC unit that covered about 1sq mile (not a whole lot) in conjunction with the free radiate, and never had issues.
Total posts : 45366For stream licensing it’s cheaper to go with someone like LoudCity (http://www.loudcity.net/) than to strike it out on your own with licensing.
Obviously this doesn’t cover your AM/FM side but it’s a cheaper alternative for streamers.
We just black out (alternative programming) our Part 15 AM during licensed performance pieces.
Total posts : 45366[quote=mlr]
Now there has got to be more to this story than was published, even at the time I couldn’t see the FCC just popping in and closing them down without giving them an opportunity to fix the problem. So either someone at the FCC took a dislike to these guys (probable), or they founght “the man” (not as likely, but possible, since people usually boast these things), or some large station felt they were being infringed upon (most likely).
[/quote]I emailed Greg from the addy on the website and asked about what happened. He didn’t go into as much of the technical side for me, but some of his comments on the situation…
“Had we been successful, small and low power radio stations could have popped up just about anywhere. This would take advertising revenues away from otherwise struggling and licensed radio stations in small markets with limited sources of income.”
and
“When you are 20 years old and armed marshals come to your door and tell you to stop what you are doing, you do it.”
..would tend to lead me to think that your “most likely” guess is probably it.
I passed Greg the address to this thread, since we’re talking about his project/history. He did mention that he may update the story on his website when he’s on the road again and has more time on his hands.
Hope he does, or maybe decides to come on in here and chat a bit about it, since I find the story interesting. Looked like they really were getting the idea flying before they were shut down, and I enjoyed reading about it.
Daniel
Total posts : 45366I would love for him to come here as a regular. Prof Nutmeg’s station and WOCR were the stations that made me really want to do this.
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