Part 15 In A Heavily Chinese-American Populated Area?

[Bongwater]

You might want to check this out:

http://www.chinamericahitradio.com/

Looks like they can use some affiliates. I don't see any Part 15 restrictions (though you might want to check.....)

It's Chinese CHR for the Chinese-American community. There's a smattering of English vocals from Chinese/Chinese-American artists in here. It actually sounds pretty good. It looks like a great way to serve a woefully underserved market - especially in college towns with a lot of Chinese exchange students. They went on last year and it looks like they're trying to build up.

If I were in such an area, I'd jump at this......

 

[stormy01]

Many of the Asians I have met are so Tech Savvy and often own 3G phones that it would be better to get on a Mobile Streaming App. for C.A.H.R.
They also seem so "on the go" that they would lose interest in something that they would only be able to listen to at home, or in a small radius...

 

[Black_Shire]

This notion of Part 15 broadcasting in densely populated ethnic areas (not necessarily Chinese-American) raises an interesting possibility. Depending on the types of buildings and the distribution of overhead power lines, telephone lines, and cable television (CATV) coax lines, a simple "hybrid" Carrier Current/NVIS (Near-Vertical Incidence Skywave) Part 15 AM broadcasting system could serve such areas very well. Instead of directly injecting the signals into the power lines or bouncing the signals off the ionosphere, however, a horizontally-mounted "stock" Part 15 AM antenna would couple the signals into the overhead lines, which would conduct and re-radiate the signals. I accidentally set up such a system one day a few years ago, and I was pleasantly surprised with the range it achieved.

I had set up a Talking House TH II transmitter connected to the outdoor ATU/102" whip antenna. All of the equipment was on the floor of the living room in my house (an old log house with a corrugated metal roof). The ungrounded ATU/whip was lying on the floor. When I walked around my neighborhood with a pocket AM radio, I was surprised to discover that the signal remained rock-steady for over two blocks, and I noticed that it was strongest under the overhead power lines, telephone wires, and CATV coax lines. Beyond about 30 feet on either side of the lines, the signal began to fade out. When I checked the orientation of the whip antenna after I returned home, it was nearly parallel to the overhead lines. I was more impressed when I saw that the whip antenna was about 50 feet away from the nearest overhead lines (the telephone lines and CATV coax) and was obscured by my house's metal roof (from the point of view of the overhead lines).

An operational system of this type could use several spaced-apart transmitters that are synchronized to avoid having a "beat" in the audio (the Rangemaster would be the ideal transmitter for this). The transmitters would be mounted to convenient existing outdoor supports near the overhead lines, with their whip antennas oriented parallel to the lines. In spots where no outdoor supports are available but non-metallic buildings (wooden houses, sheds, etc.) are located near the overhead lines, the transmitter/whip antenna units could be installed inside these structures. (In neighborhoods with many wooden structures, it might be possible for all of the transmitter/whip antenna units to be installed indoors.) For safety, the outdoor-mounted transmitter/whip antenna units should be mounted near the overhead lines rather than directly under them.

Overhead lines are usually detrimental to the performance of Part 15 AM stations, but they can be allies if one works with them.


-- Black Shire

 

[stormy01]

What if the transmitter/ATU/Antenna was purposely placed as close as possible to the Cable or Telephone lines? RF coupling should be more efficient, wouldn't it? Would one get better results further away from the transmitter?

http://www.kungpaoradio935.com/ Kung Pao Radio - You WILL listen

 

[Black_Shire]

What if the transmitter/ATU/Antenna was purposely placed as close as possible to the Cable or Telephone lines? RF coupling should be more efficient, wouldn't it? Would one get better results further away from the transmitter?

http://www.kungpaoradio935.com/ Kung Pao Radio - You WILL listen

Another poster on this board once mounted a Part 15 AM transmitter/whip antenna unit about 10 feet from a high-voltage power line, which carried the signal for miles. It could be heard within 150 feet or so of the power line.

When coupling the signal into a power line, the antenna should never be close enough that the power line could fall on it if it was ever broken loose in a storm. If you want to couple the signal into a telephone line or CATV coax (without a power line nearby) the antenna can be located closer to the line. Even then, though, it would be prudent to follow the telephone line or coax to make sure it doesn't run within the "fall/contact distance" of a power line somewhere else. Having seen fallen, live power lines "dance" on the ground, I would never want to get my Part 15 radio equipment or myself close enough to a power line to possibly get zapped by a fallen one. "Electrocution is Forever."


-- Black Shire

 

[stormy01]

What if the transmitter/ATU/Antenna was purposely placed as close as possible to the Cable or Telephone lines? RF coupling should be more efficient, wouldn't it? Would one get better results further away from the transmitter?

http://www.kungpaoradio935.com/ Kung Pao Radio - You WILL listen

Another poster on this board once mounted a Part 15 AM transmitter/whip antenna unit about 10 feet from a high-voltage power line, which carried the signal for miles. It could be heard within 150 feet or so of the power line.

When coupling the signal into a power line, the antenna should never be close enough that the power line could fall on it if it was ever broken loose in a storm. If you want to couple the signal into a telephone line or CATV coax (without a power line nearby) the antenna can be located closer to the line. Even then, though, it would be prudent to follow the telephone line or coax to make sure it doesn't run within the "fall/contact distance" of a power line somewhere else. Having seen fallen, live power lines "dance" on the ground, I would never want to get my Part 15 radio equipment or myself close enough to a power line to possibly get zapped by a fallen one. "Electrocution is Forever."


-- Black Shire

If I were to try the power line approach - my power lines are underground - don't have any idea if the range is worse than above-ground wires. What about people that live near high tension wires (100-800kV), does more voltage give more range? Or are the common 4-15kV lines that run through residential areas and higher voltage lines that run along state highways [25-75kV] better suited for this? There are transformers at least every block (500-700 feet) whether underground or above-ground and I've read that transformers reduce range when coupling an RF signal to a power line [I believe that was discovered with AM carrier current systems in college dormitories]

 

[Black_Shire]

The method I described above won't work with underground power lines. Also, the voltage on overhead power lines has no bearing on how far the signal will travel down them (although 60 Hz AC noise might be more pronounced with high-voltage lines), as the wires are just being used to conduct and re-radiate the signal.

Carrier Current radio systems, which inject the signal into the power lines, will work with underground power lines, but there are five "catches":


[1] To pick up the signal, the radio receivers (AC powered) must be plugged into the power line;

[2] Using this method often results in 60 Hz AC "hum" in the receiver audio, although line or AC plug filters can help;

[3] The signal is often blocked by AC line transformers, although neutral-injection systems can sometimes overcome this;

[4] The impedance at the signal injection point varies as AC appliances that share the line are turned on and off, and;

[5] The field strength must be monitored and kept within the Part 15 limits (the rules favor lower AM frequencies).


With these caveats, Carrier Current AM radio stations can and do operate successfully, even with underground power lines. Radio Systems, Inc. manufactures Carrier Current AM transmitters and power line signal couplers, and I think (but I'm not sure) LPB, Inc. does as well.


-- Black Shire

 

[radiocph]

I remember the carrier-current radio station we had when I was in college.

You could only hear it in the on-campus dorms.
It was used as a training ground for prospective DJ's: in order to get a show on the
FM station, you had to train at the carrier current station for an (academic) quarter or
so.

The sound quality wasn't great. There was some 60-HZ hum, not a lot, but some. Also
the audio frequency response was like listening to the radio through a telephone.

Of course, not being subject to FCC content rules, the DJ's there could get away with
a lot of stuff not permitted to the FM announcers....