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Leagl Part 15 FM Transmitter
- Thread starter DCBurns
- Start date
That's just not the way it works.. Any improvement you make will just make you hit the limit which is flea power (If it's read above so many MV at so many feet (the number escapes me..) Basically if you can hear it outside your house your illegal. Why do you think those XM-Sirius radio makers kept getting in trouble. To stay in part 15 on FM your talking feet in coverage. Which is the way it should be! People do not have a right to be broadcasters no matter how passionate they feel that their music tastes are the best. Go become a club DJ and see if you can make money or blast your boom box but stay off the air.
Scroll down or use link for an entire section devoted to this topic:
http://boards.radio-info.com/smf/index.php?board=186.0
The short answer (IIRC): 200 feet if you're lucky. AM Part 15 xmtrs get out further, but not much.
http://boards.radio-info.com/smf/index.php?board=186.0
The short answer (IIRC): 200 feet if you're lucky. AM Part 15 xmtrs get out further, but not much.
"Talking House" transmitters (you pretty much have to park in front of the house for a few minutes to hear the real estate spiel)
A church or school Part 15--which may get out a bit further than 200 feet (go to downtown Lynnfield--there's a Part 15 for Tower School or something which can be heard for a few
blocks on the expanded band AM--1640 or something. They have announcements and stuff
like third graders singing a song, and I think a church on the corner of Summer and Main had
one going for awhile that went for a block or two)*
*--actually may be one and the same--part of that church?
http://www.towerdayschool.org/
Rare, but some drive in movie theatres--tune to a freq to hear the movie. There was one up
in Vermont next to a motel--if you checked into the motel you could see the movie from
your room (maybe) and hear it on a radio
Stuff like Companion Radio, which I've mentioned picking up on Brimball Ave in Beverly at 98.9
(If you're at intersection of Essex St and Brimball and start driving toward 128, after awhile you
pick it up--it's from Blueberry Hill nursing facility--then after a block or so you lose it)
Info on the VT motel
http://www.fairleedrivein.com/drivein.html
>>SPEAKERS!!! please plan on using your car stereo (88.7FM)
for the movie sound or come early to find a parking spot
next to one of the remaining speakers that work.
A church or school Part 15--which may get out a bit further than 200 feet (go to downtown Lynnfield--there's a Part 15 for Tower School or something which can be heard for a few
blocks on the expanded band AM--1640 or something. They have announcements and stuff
like third graders singing a song, and I think a church on the corner of Summer and Main had
one going for awhile that went for a block or two)*
*--actually may be one and the same--part of that church?
http://www.towerdayschool.org/
Rare, but some drive in movie theatres--tune to a freq to hear the movie. There was one up
in Vermont next to a motel--if you checked into the motel you could see the movie from
your room (maybe) and hear it on a radio
Stuff like Companion Radio, which I've mentioned picking up on Brimball Ave in Beverly at 98.9
(If you're at intersection of Essex St and Brimball and start driving toward 128, after awhile you
pick it up--it's from Blueberry Hill nursing facility--then after a block or so you lose it)
Info on the VT motel
http://www.fairleedrivein.com/drivein.html
>>SPEAKERS!!! please plan on using your car stereo (88.7FM)
for the movie sound or come early to find a parking spot
next to one of the remaining speakers that work.
ya those pesky morals and legal thingies always seem to get in the way of people doing what they damn please
F
FPB
Guest
DCBurns said:
If you don't want a morals lesson on this subject, you came to the WRONG PLACE! These people are not your friends. Try Hobby Broadcaster instead - http://hobbybroadcaster.net.
But I do agree with posts saying that you'll get better performance out of AM than you will FM. I use a Talking House myself. It's not up to the full performance I would like (that would take a couple hundred more bucks) but there is longterm potential. You could stop by at www.radioindependentvoice.weebly.com.
The short answer is: about 250ft radius. I have heard it said by FCC Enforcement Bureau personnel that if an FM Part 15 transmission can be received on a radio...good or bad...at more than 250ft radius, then it's probably illegal.
The actual standard is 250 microvolts per meter (uV/m) measured 3 meters from the radiating element (i.e. antenna). That's a very low power. I know in some cases the FCC had a "handshake deal" that allowed college campus "leaky/radiating cable" (i.e. Andrew NF-2d) Part 15's to do the measurement 3 meters from the exterior of the building, because 3 meters from the actual radiating cable might be hard to physically get to in some dorms. But that still means the signal would be receivable, at best, some 150-250ft from the building. Still very weak.
Granted, FM reception is as much about the RECEIVER as it is about the TRANSMITTER. If you have a good radio with a good antenna, you can receive signals even at lower levels (i.e. greater distance) than a bad radio and/or bad antenna. So that can stretch the concept a little...but not much. I'd say even with the best radio and best antenna and a clear frequency, you'd be hard-pressed to receive a Part 15-legal FM transmission more than 1000-1500ft away.
Now, one little wrinkle that I've never seen anyone explore is HD Radio under Part 15 rules. Since HD Radio operates at -20dBc from the analog carrier (or -14dBc to -10dBc for some stations) it is theoretically possible to have a digital-only HD Radio signal that is Part 15 compliant. The FCC is not licensing any digital-only stations but since this is Part 15 I don't think a license is necessary. Granted, you'd have to pay for the HD Radio license from iBiquity (Not cheap! They're well into five figures.) and it's likely if anyone tried it that the FCC would change the rules pretty quickly to block it. And the ROI would be marginal...even though digital signals are, by definition, 100 times more efficient than analog...a Part 15-compliant HD-only signal would still only be receivable out to a half-mile or mile AT BEST. Probably a lot less than that for indoor listening.
To give an example, at WEOS we have W212BA, a 48 watt translator that is HD-enabled at -20dBc. The digital signal is receivable in a car for about a mile or two (terrain-dependent) covering pretty much all of Geneva. That's 0.48 watts ERP of digital going for a mile or two, but I assume that's well above the 250 uV/m threshold, too; I'm not really sure how you'd calculate what the uV/m reading is at 3 meters from our antenna?
F
FPB
Guest
aaronread said:
Ya, but you're missing the point. Under Pt-15 AM or FM, the FCC ALLOWS broadcast without a license. That doesn't mean they would allow it on HD. Anyway, how can you produce an HD signal that is "Pt-15 compliant" when there are no guidelines for it? Compliant with what?
Technically possible under AM, but have realistic expectations. I know a lot about what happened at Allston-Brighton Free Radio back in the day, and they were able to make a Part 15-compliant AM "RangeMaster" transmitter range about 0.5 to 1 mile by putting it on a billboard that was top of a large coverted-industrial building. By connecting the ground to the metal of the billboard, which in turn was coupled to the metal of the building, it was a pretty good ground and that helped get the signal out a lot more than the usual RangeMaster-style system's range (which is perhaps a quarter-mile).
However, that "mile radius" was only in cars, and wasn't exactly crystal-clear out that far, either. Legal Part 15 transmitters are limited to 100mW (milliwatts) and a 3 meter-long antenna (horribly inefficient) so even on higher frequencies (i.e. expanded band, 1610 to 1700kHz) there's just so little power coming out that it can't penetrate buildings at all.
If you need in-building listening, you need a carrier-current AM system and those are limited to a building-by-building coverage. Great for large dorms at colleges, not much good elsewhere save for very specific applications.
FWIW, I have heard of Part 15 stations synchronizing several (like 3 or 4) RangeMaster transmitters together and putting them all on a solid earth ground (like a metal billboard frame) and seeing noticeable improvement in range...out to 2 or 3 miles. Still no building penetration, but it's food for thought. Try talking to the guys at "WLOY" at Loyola College in Baltimore.
Very true. Like most language in the Code of Federal Regulations...of which Parts 11 (EAS), 15 (unlicensed), 73 (licensed) and 74 (translators/boosters) are of prime concern to broadcasters...the rules are set up to specify what you can NOT do. So if it's not in there, you are allowed to do it. That's not universally true, but for the most part it is. Of course, it's also confusing as hell and why you need lawyers to help parse all that crud. Anyways, my goofy idea about "Part 15 HD Radio" is along the same lines as using TV6 as a "Frankenstein FM" station on "87.7FM". A clever gent figured out that the rules didn't prohibit it, and away he went. I think the FCC allowed it to happen in no small part because they knew it'd be moot with the DTV migration, but nevertheless, they allowed it.
On the other hand, a similarly clever person figured out you could move AM stations 1000's of miles and make it a minor change in certain circumstances. The FCC put an official stop to that pretty quickly. And thanks to rampant abuse of minor change moves for FM translators, there's an unofficial clampdown on that (I've heard: 1st hop gets a 3 month review, 2nd hop gets a 6 month review, 3rd hop gets ignored until you go away). The FCC giveth and the FCC taketh away. And I imagine there's no guarantee that iBiquity would grant you a license to operate a digital-only HD Radio station in a Part 15 manner, either; it's up to them to grant or not grant you a license to use their technology. While excessive denial of grants would raise the FCC's ire in most cases, in this situation the FCC might view it as a favor! :
Part 15 has decent Building penetration. I use Part 15 FM and cover roughly 79 houses.
I've listened to a Part 15 AM Signal that was probably about a mile away inside a house. and as long as you were near a window it came in alright. I'm sure if had I been closer its transmitter would have been much stronger.
So the comment that part 15 has NO building penetration isn't true. But keep in Mind it can be limited if the Transmitting antenna is not above the roof line.
I've listened to a Part 15 AM Signal that was probably about a mile away inside a house. and as long as you were near a window it came in alright. I'm sure if had I been closer its transmitter would have been much stronger.
So the comment that part 15 has NO building penetration isn't true. But keep in Mind it can be limited if the Transmitting antenna is not above the roof line.
Rent a subcarrier on the local FM station...they're a lot cheaper these days as a lot of traditional SCA clients have dried up or moved to the internet.
Actually the idea you propose is not as far-fetched as one might think. The equipment cost itself would be a barrier to entry, although if you bought 100 RangeMaster transmitters, they might start giving you a hefty discount.
But the biggest barrier would be "tower rent". It'd be expensive in both time and money to negotiate the rights to put up all those transmitters - I shudder to think of dealing with 100+ landlords. Plus it'd be a pain to maintain the AC power for all of them; even though the actual electricity used is minimal, there's certain minimum costs associated with having an account with the local electric company. That said, it could work better than you might think...it's just that there's far cheaper and easier ways of reaching a mass audience these days.I was talking about Part 15 AM. Yes, FM is better at building penetration in general, although Part 15 FM penetration is not great, either.
Well if you had to be by a window, it's not exactly penetrating the building now is it? ;D
Sub-carriers: once I visited Akron OH and a friend took me to a bingo parlor and there was a radio station for the blind located there, too. I guess the bingo parlor gave money to finance
the station and they were on a subcarrier of Akron U's WZIP 88.1..not sure if they're still running
btw I mentioned the Companion Radio up in Beverly. Actually that signal is less than it used to be; obviously it's intended for the residents of Blueberry Hill Rehab and it used to have a bigger radius but now you only pick them up for a short time when you pass by the facility (you may hear WCLZ from Me. just before or after it) The site for Companion Radio says they offer
such things as music from their era, old time radio, "serenity" for Alzheimer's patients, etc.
and so on. Anyway that is always on in Beverly, as is the guy at the corner of Federal
and Rantoul Streets who seems to always be rebroadcasting Sirius' Howard 100 at 88.5 or so!
the station and they were on a subcarrier of Akron U's WZIP 88.1..not sure if they're still running
btw I mentioned the Companion Radio up in Beverly. Actually that signal is less than it used to be; obviously it's intended for the residents of Blueberry Hill Rehab and it used to have a bigger radius but now you only pick them up for a short time when you pass by the facility (you may hear WCLZ from Me. just before or after it) The site for Companion Radio says they offer
such things as music from their era, old time radio, "serenity" for Alzheimer's patients, etc.
and so on. Anyway that is always on in Beverly, as is the guy at the corner of Federal
and Rantoul Streets who seems to always be rebroadcasting Sirius' Howard 100 at 88.5 or so!
F
FPB
Guest
I agree. A good Pt.-15 signal can be heard in a building 1.5 - 2 miles away. However, it will do better in wood-frame houses than brick apartments.LibertyNT said:
aaronread said:Actually the idea you propose is not as far-fetched as one might think. The equipment cost itself would be a barrier to entry, although if you bought 100 RangeMaster transmitters, they might start giving you a hefty discount.
A 100 mW transmitter could easily be solar powered, it seems to me. But the maintenance costs would be enormous; someone would have to check each and every rig regularly to maintain the coverage.
China.DCBurns said:
Since Your Going Wayy over the limit why not run 100 watts or more?
OR Why Not just get a part 15 Transmitter, do it at least with SOME intention of doing it legal. Attach the part 15 Transmitter to a good antenna and boom there ya go.
The LAST thing you want to do is be a pirate. $10,000 is simply not worth it.
A NOUO (Notice Of Unlicensed Operation) is nothing to shrug off.
Do It Legal.
But have fun as long as you can. Serve the community, be good, keep it clean.
You'll probably never get caught, but I would be more interested in being able live with out looking over my shoulder to make sure the FCC isn't riding my heels.
just my 2 cents. Take it or leave it.
And with that Being said, Have a good day
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