Carrier Current FM

Carrier current can work on FM, but not as well as AM, from what I've been reading. The problem with FM is the wave lengths are so short that the signals aren't supposed to travel very far on single wire lines, because they leak off.

In theory you can send the signal over two wires of the power system out of phase so the wires act like a transmission line, and carry the sigals some distance, the same idea used in sending high frequency data over power lines, but I hadn't seen a circuit diagram with how to do this. The date signal went up near to the low end of the FM band, so I think FM carrier current would probably work best around 88.0 Mhz.

No idea how far the receiever was on the lines, but the picture shows the signal traveling to a box on teh other end from a house, over a set of power poles, and to another box. I don't see why the second box couldn't be the FM radio in someone's house, one with the power line as an antenna, it should go right in.

AM carrier current is based on 15.209 rules I think, where the max. field strength gives a signal of no more than a few hundred feet, so it would seem if you can get carrier current working on FM, that to stay part 15 with it, the signal coming from any part of the power line the signal is on can't be more than the regs allowed, the 250 microvolt rule for the USA. The signal should stay ON the power lines though much farther than that.

Thanks for your playing of classic and progressive rock, that's some great stuff man, so many good sounds from that time that are unheard by anyone, but my classic FM station is only playing stairway to heaven and Free bird, as it's iheart Radio. It's like forgotten history, why don't they play that stuff?

You could couple the signal to the power line, telephone line, cable TV line by wrapping several turns of the antenna around the insulated cords or lines. I wouldn't try a direct connection to any conductors for safety and also, in the case of cable or phone, to avoid disrupting their signals.

I don't expect much success from this but why not try? My opinion on legality would only be a guess so you will be on your own.

Neil

I think I got it wrong about feeding the two wires of the power line with out of phase signals, it should be balanced feed, which would be in-phase signals, so that the signals on the two lines would mostly cancel out, and instead carry farther along the line than a signal could in free air from an antenna.

Thinking about it more, maintaining the balance across the two lines that the signal is on would be the most important thing, for most range, and keeping the signal on the line. To maximize it as a pro you might need adjustable balance and phasing, then to go away from the power line and adjust for minimum radiated leakage signal.

For a simple test, if you're tech-ready, you could take a regular power cord, put two capacitors in series with the ends, maybe small ones for FM, less than 100 pf, .1nf or so, then feed that with the output of a transformer sized for the high frequencies, with neither side grounded.

If I were an electrician I'd try somehing like that.  The electric lines travel right in front of my house.  When I'm on the porch I could have touched them if they were not live.  The transsormer is where the traffic light is and it travels along the neighborhood and over to the building across from me.  So its why I thought about it.  Keeping 250 uV/M would be ideal anyways as you would not want to bleed all over the FM band.  I've seen part 15 transmitters where if you have an FM Radio 10 feet from it it would bleed but when you go further away it stops and becomes normal.  That in mind I may want to cut back just a bit to prevent such an issue but be able to travel several feet maybe 1/4 mile along the lines keeping the signal clean and interference free.  I'd like to see someone try it and report what happens.  Now taking the wire from the Whole House transmitter and wrapping it around insolated wire is an idea I thought of too.  The signal would sort of follow it and if you had neighbors who like your station could listen on those radio's with those electric cord antenna's.  Neat stuff.

@the person talking about my Progressive Rock (can't remember): I am trying to bring that 70's album Rock feel that has been missing for years on Radio.  Even if my station gets out a few feet (1/4 mile on a car Radio) I can still attract listeners to tune in on the Internet if they love my music.  Its why I do what I do.  Radio needs to get back to what the people want.  When I took Radio and Cable TV I learned how a station was supposed to meet the PICN (Public Interest Convenience and Necessity) and if not they could lose their license to operate.  Adults want music other than Rap and Top 40 on air.  Hits are good to a point, but should not be the only factor in a playlist.  I play what the adults want to hear and I even say over the air that my station is an Album Rock Station.  I won't waiver from that which is sacred in Rock.  If we don't preserve good Rock it will be lost to Rap and Top 40 crap forever.  Its why I'm pushing so hard for the FCC to give us the 1,000 uV/M on FM (Without the fudge factor) wo it would be on the legal books.  Better yet we should be (on the books) allowed to run 1/4 watt into a rubber duck indoors on blank frequiencies with nothing but FFFFFFFFF They should not have any back ground music on them and be 2 decimals apart like 96.3 (transmit on) and 5 is blank and so woulod 96.1 be blank.  Good Radio could help everyone.

I do know also that ground can sort of follow the power lines too.  FM can do this I'm sure becuse the wireless intercoms from Radio Shack used the power line as an antenna.  In fact you could talk to your neighbor 1/4 mile down the road with them or accross an entire campus of dorms.  That in mind I don't see why FM Radio would be any different.

The reference i was saw was about data being sent over the power grid from one modem to another at up to VHF frequencies. The signal was broken up in a bunch of narrow signal spikes over a wide band, so if there was signal interference to one of the spikes, the others would pick up the slack. That they could do that in the VHF range, means it could possibly work on FM.

There's another article posted here in another place that says it won't work, but I wonder if they tried it, or if it's just the theory that it won't work, because the wave length is short compared to the very long wires. That's why I had the idea to specially tune the power lines as an open wire transmission line instead of a long wire system.

I agree, since it's unknown, engineering tests should be done, but casual tests wouldn't be so bad either. My idea is that any decent range increase you can get on FM with carrier current over antenna might be worth shooting for. Since FM is based on signal strength at a certain distance, not transmitter power you might be able to send more power to the line.

I like your idea about a transmitter that checks for open frequencies on FM before transmitting, and you might be able to do something like that with a software based radio transmitter. Software on a sensing antenna might be able to even keep the signal on the power lines in balance for minimum radiation at all times.

Wrapping the wire from the Talking House around cords and things like other wires is good to try. I found that sometimes the tuner couldn't lock in properly, like half the time, because it's seeing an odd load I guess. Wrapping around AC mains and stuff makes a capacity connection, so the power is going metal to metal like two plates, with the wire's insulation in between.

Yes there's so much great prog and classic rock that people just wouldn't believe it! It's a whole world that hasn't been heard since then, and forgotten. I complained about it before to a friend who said that our album rock station will only play songs that charted in the top 20 for every year that they play, which is about 1970-90, with some newer tunes in there, and maybe a couple before 1970, plus some local bands that hits in the area. Let me guess, they probably don't have a music director. They wouldn't need one. I'm guessing they play 500 songs max.

I'm blown away when I hear some of the online stations where every single song is something I've never heard and it's great! Now there's Atrain, have you listened to that guy's Free Thinker show? He plays classic rock too, in a mix with new rock, and I haven't heard a rap or top 40 in there yet, so he has seen the light.

I do think the FCC is right to keep its hands mostly off of the programming and not do PICN as you said. They can be free to fail, the stations. Was PICN ever actually serious, or just more of a guide and your station decided what that meant? I think it fails on both the listener's and the station's sides. Most stations don't have request lines or a live DJ that's always there, so they're not in direct contact with their listeners, and I think listeners have been dumb down by radio and are catatonic hearing wise and don't know what sounds to ask for, because nothing different is ever played.

Good DJs used to play the hits, but then also knew the music and would throw in a new song that they thought their audience would like, introducing them to new music. It would be like a friend making you aware of new sounds. Not on radio today, the only request lines you hear are on the national shows like Delilah and Open House Party, seems like.

Those FM intercoms, they might be FM but the frequency is way down low, kilohertz not megahertz. That's as far as I know, maybe there are VHF carrier current intercoms.

I remember the 49 Mza intercoms.  They did use the power lines and they were really good at transmitting an entire neighorhood or school campus especially wnen they had their own power transmirmer usually at the beginning of the campus.  I was able to transmit from North Wing 3 all the way to the AB cottage at Michigan School For The Blind.  Pretty nifty I thougnt.  We would talk after school up till bedtime at times.  If I wanted to get ahold of my friend Wally I'd call him.  We tried to get 49 Mhz Realistic intercoms on the same frequency so we could talk back and forth.  It was awesome.

Playing around with FM Transmitters as a kid I never tried the power line trick but I do remember connecting one to a police scanner and getting out 2-3 miles.  And I got a hold of a FM Stereo antenna (beam) and I even got out to the Grand Ledge High School wich was west of me.  Being 3 miles from the airport I didn't want to transmit east of my house.  This was backi on 79.

Yes I think more work needs to be done experimenting with carrier current FM.  Someone who knows how to wire up that kind of stuff but I really don't see why it would not work if tuned right.  Especially around 88.1 to 96 Mhz as its closer to 49 Mhz where it worked for the intercoms.

Now they sold for a short time AM Wireless Intercoms that transmitter just around 1700 Mhz.  The first cordless phones (Before the 46-49 Mhz pair was there.  I didn't play around with those too much but I do also remember the wireless phone hacks that used the 46-49 Mhz and there were a few that used the old 1700 Mhz band and they even had a high quality audio where you could use them for dial up computer connections (remember those)?

I know the FCC reads these forums you can bet that and I'm also sure we could get a lot done.  Doesn't matter how much the corporations want to bribe officials their is starting to be public support for personal micro broadcast stations.  So they can only fight so long and I do know from what I've learned in Radio there is a PICN rule.  I don't know if the FCC has enforced it in years, but nevertheless its there and one who has the right lawyer could argue that if Johnny Smith's one mile or 1/4 mile station is hurting you than your not following the PICN and YOU the licensed broadcaster need to either follow it or take a hike.

LPB (Low Power Broadcasting) issued a technical paper on "Carrier Current Broadcasting Theory." In Tech Note # 1 they said:

"Carrier current FM broadcasting is not possible because at the much higher frequencies of the FM broadcast band the loss characteristics of the low voltage power wiring would consume all the FM signal before it got more than a few feet down the AC power wiring."