Tim does more radio oriented things than anyone I've ever known in the business. He might just be able to fit in a Re-Certification Service for the ordinary part 15 riff-raff.
Count me in I'm ready to send my C.Crane FM2 for evaluation.
If we all had professionally "re-certified" FM transmitters the problem would be solved and the ALPB could put a sticker on it.
I have to wonder if it's constructive to continue to talk on and on about what power you'd like to have with Part 15 FM, without doing anything about it.
The rules right now are clear. Yes, it is difficult to measure if your transmitter is compliant. But taking matters into your own hands and dealing with unknown transmitters and milliwatts of power is definitely getting into the non compliant zone, and again, I don't think it's constructive (or legal - there's no such thing as being sort of legal).
Personally, I think if you use a unmodified, certified transmitter, then you'll be OK 99.9% of the time. If the FCC shows up at your door, at least you're demonstrating that you're attempting to be compliant with the rules. I doubt they'll listen to arguments about milliwatts into a rubber duck being similar to a certified transmitter such as the Whole House 3 with audio cables attached because some field tests at Part15.us were performed.
And there's always Part 15 AM.
Postscript: Whenever you're looking at a set of rules, you have to consider the intent of the rule makers. It's pretty obvious that the intent of Part 15 FM is to allow a range of several hundred feet. Yes, it's possible to get more with a combination of factors such as antenna height and sensitive receivers, along with some creativity, but unless the FCC's intent has changed, there's no way they would consider, say, 800 feet to an unknown, possibly lousy, receiver as the norm. They actually come right out and say they expect a legal transmitter to get 200 feet range at most. That's intent right there.
As for AM, the intent is obviously to allow greater range, while ultimately being throttled by the antenna+ground wire+feedline rule. Again, you can get potentially up to a mile range with a legal transmitter, maybe a bit more with a very sensitive receiver, but it's unlikely that you'll get a lot more (i.e., miles as I've heard some talk about) unless you're 'bending' the rules (most commonly the ground wire). To portable or handheld receivers I've been able to get 1/4 to 1/2 mile range, depending on the sensitivity. But that's still much, much better than a few hundred feet.
Artisan and Tim have good points.
Now that we have Tim in Bovey's test results we are awake to the state-of-affairs with FM transmitter certification, which is not what anyone suspected or expected, but there it is.
If we count all the times "rubber duck" has been said and line the rubber ducks in a row, it's probably time to rest the case, as they say in court.
Along with considering what the FCC had in mind when drafting the rules for field strength, another fact seems to get kicked aside, and that is the FCC does not view Part 15 as a vehicle for community broadcasting, and there is zero chance that will change, since the licensed services are intended for community broadcasting, even when license holders do a poor job.
While FM is spectacular for its sound quality, AM is amazing for its range, and Part 15 AM has a chance of offering a semblance of community service, if you view a lot of open space as a community.
For everyone who loves a music style so much they want to share it as widely as possible using radio, the desire does not qualify as a license. It might be simpler to hand out stacks of CD records.
I have a lot more to say on the subject and plan to post messages here at part15(dot)us until nuclear radiation closes everything down in 2045.
To me, personally, it's clear that the FCC's intention for part 15 FM is for personal "broadcasting' e.g. to play your CD's throughout the house, to hear the home stereo in the garage, to play your mp3 player into your FM car radio, etc. Clearly it was never intended to start a bunch of little radio stations.
I also suspect the intention wasn't for AM Part 15 to spawn a bunch of little stations, either. But the rules / legacy of AM Part 15 goes back a long way and there would be an awful lot of little transmitters out there over the past 70+ years to try to stop people!
Remember, that I did some informal range tests with the two previous FM transmitters I tested. Both of which, as received, were well over the legal limit and my received range with a "good" portable radio AND my car was at best 300 feet (depending if I held the radio just right). These were line of sight tests. I could clearly SEE the transmitter from where I was listening.
Talk of rubber duck vs other antennas doesn't really matter. If a given amount of power goes further with a different antenna, it's because that antenna is offering some gain over the other, and therefore creating a stronger field strength.
Exactly what sort of "rubber duck" are you talking about? The one included with the Whole House 3.0 that I tested was nothing more than a few inches of braided wire shoved into a cheap slightly flexible plastic tube. It was most definitly NOT a real "helix" type antenna that you find in a real ham radio handie talkie antenna, or even a portable shortwave type antenna. The radio with the WH 3 was a piece of wire. Connected to the transmitter with one connection, so a plain bolt on the transmitter. A real antenna has an SMC, BNC, etc connector with Two connections, the shield and center or hot. These go to two different helix coils in a real rubber duck. The phrase "rubber duck" when referring to what comes with these transmitters is another huge variable.
It would be possible for me to adjust the C. Crane to the legal limit and range test. Whether I have the time is hard to say. But I already know I get 35 to 40 feet at 110 uV/m. So even if setting it to 250 uV/m doubled the range that would only be 80 - 100 feet. And that's into a relatively sensitive portable radio with the transitter right in front of me.
Clearly the FCC intent is to limit range. Otherwise some sort of simple output power rating would be suitable for their rule. But with a given power as the only rule there are too many other variables. Efforts to get maximum range are stopped by the field strength rule. As, siply, a given field strength equals a given coverage, period. If a different antenna design increases range it is also increasing field strength. You can't get around that. If a given transmitter is at the limit with the provided antenna, and you find an antenna that increases range, you've defeated the fact that the provided antenna was sent with that transmitter as the combination created the limit desired by the maker and demanded by the FCC.
TIB
I could imagine. I don't know what the FCC would think about that, but the obvious would be they would love the idea. However I bet someone somewhere would make a stink about that too and try a lawsuit of some sort. It would have to be kept low key however otherwise there would have to be an FCC agent to supervise every unit he re certifies and adjusts for 100% 250 uV/m at 3 meters. At least folks would have got what they should get out of their part 15 transmitters as far as the range. There would have to be some sort of disclaimer too in case the unit was somehow over the limit due to the vibrations from shipping which could put you at 275 uV/m at 3 meters. Every time someone tries to do something good for the rest of us folks there will always be someone to try and ruin things.
Mr Blare opines and posts about compliance with FCC §15.239: ... Rich believes adding an odometer is our responsibility and not that of the FCC. ...
Apparently Mr Blare expects (or hopes for) the FCC to provide that "odometer."
Can anyone logically explain/justify why the FCC should be responsible for that?
Note that the FCC does not provide field intensity measuring equipment/odometers for ANY service subject to its jurisdiction.
Carl wrote:
"Along with considering what the FCC had in mind when drafting the rules for field strength, another fact seems to get kicked aside, and that is the FCC does not view Part 15 as a vehicle for community broadcasting, and there is zero chance that will change, since the licensed services are intended for community broadcasting, even when license holders do a poor job."
You have to think more positive, Carl, you have to believe in the document you want to give to the FCC. If there's a zero chance of getting a classification like BETS -1 in the US then all this is just talk and as Artisan says it's all talked out.
Mark
I've written this before but it seems to fit the discussion so I repeat.
My intent on FM is to provide coverage to my house. From experiments with different antenna lengths and even with dual antennas, I find that I can cover my house and part of my yard with a system which gives about a 200 foot range using a car radio, and a bit less using a portable. This is the best I can do to attempt (and I hope, achieve) a legal operation. This range as it relates to 250uV/m at 3m is consistent with Tim's data and the FCC guidelines.
My property is 110 feet wide and 200 feet deep which is pretty much the standard here. At best, I would expect my signal to be usable only by my adjacent neighbors. This is certainly not going to serve as "community casting". Those living in apartment units have a larger potential audience but the community may only be those living in your complex.
I am realistic about the failure of Part 15 FM under the current rules to provide for broadcasting, and even if the field strength were to be quadrupled, by law or by cheating with a pot twist, my potential audience would perhaps quadruple from two neighbors' homes to eight. Not worth the risk in my opinion.
Sorry to sound negative, but it is what it is, and for housecasting Part 15 FM works.
Neil
Mark, I think it is all talked out. It doesn't appear that we have a strong argument as to why the FCC should up the field strength and it does not appear that such an argument will result from further talk.
Rich (post # 36) that's not what I said nor is that what I meant by what I said.
Mr Blare posted ... Rich (post # 36) that's not what I said nor is that what I meant by what I said. ...
OK, then could you please tell us (accurately) what you meant by what you said?
Rich, could you feign to misunderstand someone else once in awhile?
I explained what I said in what I said.
Gibberish, Mr Blare.
This has been bubbling a bit inside me for awhile, but why the hell would the FCC ever want to increase part 15 power? All that would accomplish is more noise on an already noisey spectrum. The CFLs, dimmers, AC motors, TVs, all radiate under current part 15 regs. By loosening regulations we'd be shooting ourselves in the foot.
Part 15 was never in anyway meant for broadcasting, if anything it was intended for experimentation. Thats why there are field strength limits or antenna limits. They intended somebody with electrical RF background to be messing with this stuff. Someone with the proper equipment and know-how. Not average Joe Blow grabbing a transmitter and playing radio.
It just so happens we get lucky with part 15 AM being simple enough to stay legal and get some use out of it.
FM is obviously not meant for any useful range, and never will be.
How does one make a "fool proof" Part 15 FM transmitter? As Rich and Tim have pointed out it matters not that a unit is "certified" by the FCC when the end user may inadvertantly cause the unit to exceed the allowed field strength by simply connecting a longer audio or power cable to the unit.
It's not so much that the FCC needs to provide the "odometer" (read FS measuring device.) Instead, the certification criteria to maintain proper operation needs to be supplied with the unit as the manufacturer of the units seems to be lax or purposely vague in that area.
It would seem the only solution would be to produce an all in one, self contained, battery powered unit. No external connections which permit plugging in cables thus altering the performance of the unit. A built in MP3 player perhaps but this makes a live broadcast somewhat impossible.
For that matter, as it has been shown, simply changing the HAAT alters reflections which can reinforce the field strength at certain distances to the point of exceeding the permitted amount. Perhaps the NOUO's should be based on field strength measurments at a prescribed distance (3 meters) to negate that effect. No more drive by measurements. Of course it goes without saying that some field strengths are obviously in violation regardless of where the measurement is taken.
As the general discussion has focused, the opinion seems to be Part 15 FM was not intended for hobby "broadcasting" and requests for increased range are the proverbial snowball in the devils hand. It's going to take the creation of a class of service, licensed or not, to change the future of Part 15 FM hobby broadcasting.
An act of Congress you say? Yes!
Hobby broadcasting can be included in experimentation, but I think that Mighty1650's statement that Part 15 wasn't intended to provide any sort of useful (or as I like to think of it, extended) range is right on the money. I don't think that the FCC could forsee sensitive AM tuners, or the creativity in AM Part 15 practioners in their zeal to get every last inch of range they could.
They corrected that mistake for FM. Even in Canada, with our increased field strength rules, Industry Canada expects that the range for a BETS-1 certified transmitter to be 100 feet (and that's written right in the rules). Of course, the rules also state a maximum of 100uv/m at 30 meters, and it's that that the manufacturers use for certification.
I'm sure everyone here has an opinion as to whether it would be possible to increase FM Part 15 power limits, however you do it, or change the measurement criteria to determine legality. But you'll only know if you try. I do believe that this is talked out. If no action is forseen, it might be better to move on to other topics.