I am curious about this. I have been reading the large assortment of posts, and have commented on one that was dead with a question. Not wanting to continue growing that dead thread with another question, I will ask it here.
It appears that at least one of you are running Carrier Current succesfully. I am wondering if anyone else is doing it. Or if you have tried it, and failed.
I, like some of you, have a desire to bring a service to my small town. I missed the LPFM filing due to bad timing.
It appears the FM terrestrial is not an option due to the restrictions imposed.
I haven't ruled out AM linked terrestrial broadcasters, or a combination of AM Carrier Current and AM terrestrial broadcasters.
As a side note, I even popped an email concerning LPFM, or even FM filing windows to one of our local politicians. He is now a presidential candidate. I guess I didn't warrant a response, as I got none!!
So, to reiterate, who is running Carrier Current / AM or FM?
Successes or failures?
On the hot tap or neutral tap?
What equipment?
Problems with powerline owners i.e. did they care?
Perhaps I should have posted a questionare!!
I haven't decided how far I will go with this quest. But on a side note, there is a hamfest in central TX this weekend. There is usually a lot of "stuff" Who knows I may run a cross a LPB transmitter set up there. I already have a TH 5.0 that I am experimenting with.
Craig
I'm glad someone is thinking about carrier current, it's a pretty well unsung technology in part15 land it seems to me, and there are very few articles that clearly deal with the subject and lay it all out.
I read a comment by a commercial radio engineer who said that carrier current is becoming a lost art because the people who pioneered the technology back in the day are gone now. That makes sense since some of the examples of people discovering it are from the 1930s, and ham operators using it during World War II.
I did another post about my setup with the Talking House, it's pretty informal, and the effect, since no one else has apparently named it, I'm calling it "Incidental Carrier Current". It deals with a regulation 3 meter antenna wire, in close proximity to a power line, situated in such a manner as to induce in the line an inductive signal that travels along the line for a certain distance, while at the same time reducing direct antenna radiation.
There's the abstract from my patent application. Heh, joking. I like it because it's safer, unless the antenna was naked and would fall into the open fuse box across the 240 volt main. 🙂
I've wondered about rights issues with feeding RF signal power into AC lines, but can't find any instances of that being brought up, good or bad. My take on it is that as long as your station wasn't causing any interference to other stations for listeners, it doesn't concern people that much.
If you think about it, with all of the AM radio stations around, they'd put large amounts of RF in power lines already, the lines acting like longwire antennas. I'd imagine other problems more, like a worried landlord over apparatus connected to the breaker box, if it becomes known, otherwise Carrier Current seems to be very stealth. People won't tend to believe there's a radio station in a building, because they can't see an antenna.
I'd learn more about it and just try it. I'd check with Blue Bucket Radio who is using Incidental Carrier Current as well, and Carl Blare, he has some heavy pro carrier current equipment, though I think it's been out of commission lately due to a crystal break, but he has run it before. Those were some posts I read last year.
The AC powerline utility companies do not themselves police what gets connected to their lines unless a disturbance is caused to power distribution.
The all important matter of safety is addressed by the local and federal electrical codes which are a function of government, and the question of electromagnetic frequency radiation from powerlines is addressed by FCC rules.
Some electric companies themselves use carrier current communications on their own power lines, also regulated by the FCC, and because of that the frequencies used by power customers are regulated by FCC... you cannot use every possible frequency... only certain frequencies are free to use by the public, defined by FCC rules.
Effecient transmission of radio signals over powerlines is generally possible from long wave, medium wave, and high frequency up to a practical limit of approximately 30 MHz (if I have that number right).
FM is not considered possible on carrier current, unless it can be done at a very short distance (?)
FM is possible on cable systems, and some cable systems have included an FM band with cable only FM stations that serve FM customers whose FM tuners are connected to the cable systems in lieu of an antenna.
My station, KDX, was originally intended as a cable FM station after I witnessed a cable FM service in use in Little Rock Arkansas (in the 1970s), but when I checked I found that cable FM was not available in my hometown which only offered cable TV, so I switched to Part 15 AM, SW, FM, using transmitter/antennas.
As Tim in Bovey has shown it is possible to transmit radio on the audio portion of a video channel on cable TV. He does it I think on the program guide channel in his city.
The efficiency of AM carrier current is a very unpredicatble beast because the properties of power lines differ wildly from one location to another.
While my carrier current station was running I was unable to match properly to the power lines (for unknown reasons) but was able to match using neutral injection, with a coverage area that was no different than I was also able to achieve using an SSTran AMT5000 Transmitter with antenna and ground radials.
Others, including MRAM, have covered much larger areas using carrier current.
Thanks to Jeff Station8 the ALPB website has a nearly complete collection of papers and schematics published by LPB (Low Power Broadcasting) while the company served the carrier current field.
I was using Carrier Current prior to building out a new studio/workshop. The station was taken down when I moved out of the house and I haven't had time to put it back up. Soon I hope.
I was running about 5 watts using neutral injection. The range was substantally better than the Part 15.219 installation.
The plan is to install the transmitter in the 2nd floor studio/workshop and the CC coupler on the first floor. RG-8 or LMR-400 cable will interconnect the two.
The reason for placing the coupler at ground level is to facilitate connection to an isolated ground rod located outside the building, a necessary component of neutral injection.