Can Part 15 FM really be legal?

[jimbo]

I had a chat with my local FCC field office and was told if the trasnmitter is not FCC certified then my signal is not legal. Apparently even if your field strength measurement checks out at 250 µV/m at 3 meters you are not legal unless your xmitter is FCC certified (or using the pronounciation of the FCC rep "sir-terf-ah-kaydid). I specifically ask about my Ramsey FM30 that lists .25mW output, again, not legal because it's not certified. That sort of surprised me because I thought the part 15 regulations dealt only with field strength. So where could I find a certified part 15 FM transmitter? My Google searches are not turning up one.

 

[JasonW]

Panaxis Productions www.panaxis.com makes a nice FCC-Certified Part 15 FM transmitter called the ACC100. -- Jason

 

[jcolletta275]

Methinks someone at the NAB has their hands in the back pockets of your FCC field office

 

[JasonW]

Methinks someone at the NAB has their hands in the back pockets of your FCC field office

No, the FCC field office is merely following the rules for Part 15 FM, which are much more restrictive than the rules for Part 15 AM.Part "d" of Section 15.239 (Operation in the band 88 - 108 MHz FM band) says the following about non-certified and custom-built Part 15 FM transmitters (parts "a" through "c" cover the allowed frequencies, allowed field strength, and out-of-band emission limit)d) A custom built telemetry intentional radiator operating in the frequency band 88 - 108 MHz and used for experimentation by an educational institute need not be certified provided the device complies with the standards in this part and the educational institution notifies the Engineer in Charge of the local FCC office, in writing, in advance of operation, providing the following information1) The dates and places where the device will be operated;(2) The purpose for which the device will be used;(3) A description of the device, including the operating frequency, RF power output, and antenna; and,(4) A statement that the device complies with the technical provisions of this part.Non-certified and custom-built Part 15 FM *voice* transmitters aren't legal. If I were going to do anything more than just broadcast music around my house (such as setting up a neighborhood FM radio "network" using multiple transmitters), I'd definitely use only FCC-Certified Part 15 FM transmitters such as the Panaxis Productions ACC100. -- Jason

 

[jimbo]

The FCC paid me a visit today - the senior agent from the Denver office at my door. The Ramsey FM100B I had is history. I was using the whip antenna and the agent said my field strength was well above 250 microvolts from the street, about 60 yards from the transmitter. My notice of unlicensed operation will have the exact measurement. Nothing fills your Depends like having the FCC at your door. The certification really doesn't matter, it's the field strength that does matter. The Ramsey was not certified. But then even certified stuff can cause a problem, just ask the XM folks.I asked about the ACC100 and that should be fine. It's certified but the real key is the field strength. Hopefully that's legal. I don't want to be spending time as a guest of the Feds in Florence, Colorado.

 

[JasonW]

The ACC100 FM transmitter should be fine--it's been around a long time.Just a thought, though--why not let that FCC field agent know when you get the ACC100 running at your location? He will appreciate it if you demonstrate a willingness to work within the rules.If he should find its field strength to be above the allowed level (unlikely), you could bring it into compliance with him present by snipping off a millimeter of the antenna wire at a time until his meter reads a legal level.One caveat, though--with Part 15 AM, it has been demonstrated that FSMs can't accurately measure such low field strengths (William Walker got an FCC visit and TURNED OFF his transmitter, yet the agent's FSM still indicated it was over-limit because it picked up AM noise in the area). The same may be true for Part 15 FM. -- Jason

 

[jimbo]

Good tip Jason. I did tell the agent I plan to be back "on the air" with ACC unit and I would notify him when it's on. I invited him to come back and measure it because I certainly don't want strike 2. Having the Feds at the door is something I don't want to experience again. I especially like your idea of turning off the unit and seeing what kind of measurement is obtained. I wish I had thought of that when I had the Ramsey.

 

[JasonW]

Good tip Jason. I did tell the agent I plan to be back "on the air" with ACC unit and I would notify him when it's on. I invited him to come back and measure it because I certainly don't want strike 2. Having the Feds at the door is something I don't want to experience again. I especially like your idea of turning off the unit and seeing what kind of measurement is obtained. I wish I had thought of that when I had the Ramsey.

Also, field agents often cut users more slack if they're using FCC-Certified transmitters, even if they are a tad over-limit (due to statistical variation).The ACC100 is a monaural transmitter, but at legal Part 15 FM power levels it doesn't pay to broadcast in stereo, as it noticeably reduces the already-small effective range. I have a C. Crane Company FM Stereo Part 15 transmitter, and while it sounds great, I can't get clear reception on a Walkman more than about 30 feet away at ground level. The ACC100 is good out to 50 feet at ground level. -- Jason

 

[Grrrradio]

Hell, I'd better watch out, then... I recently purchased an off-the-store-shelf, dial-tuning (!) FM modulator made by General Electric, for use with my iPod. It runs on 2 AAA batteries and is specced at 10 mW current consumption. 10 mW * 3V = 30 mW power consumption, probably around 15-18 mW of actual RF output once inefficiencies are taken into account... yet the other day, it put a "seekable" signal to my car, some 85 feet distant from my third-floor apartment. My car happens to seek something like a 47 or 48 dBu, right around the specified 250 uV/m limit... so I'm putting out a signal of the strength that got Jimbo busted, for over half the distance he was sending it!My question is... how the hell is the FCC finding out about transmitters like Jimbo's, that send 48 dBu sub-fringe signals for maybe a city block? Does their aggressive enforcement arise from pressure by NAB and/or NPR stations, or just Lord Acton's old maxim that power corrupts? Don't they have anything better to do? Remember the old theory about the frogs whose water is heated up, little by little, so they don't realize they're well on the way to boiling? One has to wonder if that's where we're at, with regard to freedom vs. tyranny in this country...

 

[4dude]

I had a chat with my local FCC field office.

Why??? Best to just keep quiet about such things.....

Methinks someone at the NAB has their hands in the back pockets of your FCC field office

I also think that.....

 

[FreddyE1977]

Is anyone out there familiar with this station?http://wkmxlive.com/news/articles/article255.asp This is the site for a Part 15 station in East Liverpool, Ohio. Supposedly this station is being operated by a local business/community group, upset because Forever Broadcasting has decided to move their only local station,1490 WOHI, down the road into Pennsylvania in order to rimshot syndicated sports-talk at the Pittsburgh market. They had already moved the FM sister station to PA, and an AM on 1570 left town years ago. This left them with no local source of broadcast news or talk about local issues. As a solution, they havedecided to take the bull by the horns and put their own replacement station on the air.I can't confirm it, but supposedly they are getting an 8 mile coverage radius out of two synchronizedPart 15 AM transmitters on 1620 kHz. I have also heard that they got permission to install one of thesetransmitters on top of the City Hall.....which ought to provoke a very interesting Constitutional crisis if theFCC boys ever decide they want to raid them and shut it down. I do have to give them a lot of credit for taking a direct and innovative approach to solving the ongoing problem of consolidation and loss of community service.

 

[SML]

The FCC is usually not looking for pirates at all. They usually act on the basis of a complaint. The FCC usually has more important things to do than chase up and down streets sniffing for signals.It sounds like one of your close neighbors didn't like your choice of tunes.

 

[rfry]

One caveat, though--with Part 15 AM, it has been demonstrated that FSMs can't accurately measure such low field strengths (William Walker got an FCC visit and TURNED OFF his transmitter, yet the agent's FSM still indicated it was over-limit because it picked up AM noise in the area). The same may be true for Part 15 FM. -- Jason

Has this been verified, or is it maybe just a Part 15 legend? Commercial MW field strength meters such as the Potomac Instruments FIM-41 can measure fields down to 10 µV/m or less -- which is far less than a fully legal Part 15 AM can generate at the relatively short distances that the FCC would measure them. And unless the FCC agent was a real dunce, he would be careful to identify what he was measuring by listening to the transmitted program via the audio output jack on the FI meter. It is highly unlikely that he would mis-identify local noise as an excessive field being radiated by the station he was checking. Commercial meters for FM fields are equally sensitive.

 

[JasonW]

One caveat, though--with Part 15 AM, it has been demonstrated that FSMs can't accurately measure such low field strengths (William Walker got an FCC visit and TURNED OFF his transmitter, yet the agent's FSM still indicated it was over-limit because it picked up AM noise in the area). The same may be true for Part 15 FM. -- Jason

Has this been verified, or is it maybe just a Part 15 legend? Commercial MW field strength meters such as the Potomac Instruments FIM-41 can measure fields down to 10 µV/m or less -- which is far less than a fully legal Part 15 AM can generate at the relatively short distances that the FCC would measure them. And unless the FCC agent was a real dunce, he would be careful to identify what he was measuring by listening to the transmitted program via the audio output jack on the FI meter. It is highly unlikely that he would mis-identify local noise as an excessive field being radiated by the station he was checking. Commercial meters for FM fields are equally sensitive.

Why don't you contact William Walker through his WILW Radio web site? He can give you the full particulars of the incident--the FCC Field Agent's name, the date, the Field Strength Meter he was using, and so on. -- Jason

 

[rfry]

Why don't you contact William Walker through his WILW Radio web site? He can give you the full particulars of the incident--the FCC Field Agent's name, the date, the Field Strength Meter he was using, and so on. -- Jason

Fair enough, I guess, although I thought you would be able to support your post by your own research/knowledge.But I'll try to contact Mr. Walker to see what develops.

 

[JasonW]

Why don't you contact William Walker through his WILW Radio web site? He can give you the full particulars of the incident--the FCC Field Agent's name, the date, the Field Strength Meter he was using, and so on. -- Jason

Fair enough, I guess, although I thought you would be able to support your post by your own research/knowledge.But I'll try to contact Mr. Walker to see what develops.

The account of someone I know to be trustworthy (William Walker, in this case), plus the fact that his local FCC field office apologized to him after the incident, is all I need to know that FSMs aren't infallible when used to measure Part 15-level emissions. -- Jason

 

[rfry]

The account of someone I know to be trustworthy (William Walker, in this case), plus the fact that his local FCC field office apologized to him after the incident, is all I need to know that FSMs aren't infallible when used to measure Part 15-level emissions. -- Jason

From my emails with Mr. Walker sent and received today, his account of this scenario, and the FCC apology about it all are unable to be substantiated in any way other than the postings of Mr. Walker, himself, and/or those who quote him.Commercial field strength meters easily are capable of measuring the field strengths of fully legal Part 15 AM & FM systems. "Part 15" operators believing otherwise will proceed at their own risk (not that it matters to me).

 

[JasonW]

The account of someone I know to be trustworthy (William Walker, in this case), plus the fact that his local FCC field office apologized to him after the incident, is all I need to know that FSMs aren't infallible when used to measure Part 15-level emissions. -- Jason

From my emails with Mr. Walker sent and received today, his account of this scenario, and the FCC apology about it all are unable to be substantiated in any way other than the postings of Mr. Walker, himself, and/or those who quote him.Commercial field strength meters easily are capable of measuring the field strengths of fully legal Part 15 AM & FM systems. "Part 15" operators believing otherwise will proceed at their own risk (not that it matters to me).

Did you communicate with the FCC Field Office that was involved in this incident? If so, I'm surprised that you didn't reproduce their refutations of William Walker's account of the incident or even mention your communication with them here. Until and unless you do, your claim that Willam Walker's account is "unable to be substantiated in any way other than the postings of Mr. Walker, himself, and/or those who quote him" isn't worth a bucket of warm spit. -- Jason

 

[rfry]

Did you communicate with the FCC Field Office that was involved in this incident? If so, I'm surprised that you didn't reproduce their refutations of William Walker's account of the incident or even mention your communication with them here. Until and unless you do, your claim that Willam Walker's account is "unable to be substantiated in any way other than the postings of Mr. Walker, himself, and/or those who quote him" isn't worth a bucket of warm spit. -- Jason

Before my last post of yesterday, I sent Mr. Walker the following email text about his reported encounter with the FCC. "I understand that this is what you have stated/written, but do you have any means to validate your statements, such as copies of written communications about this from the FCC?"Mr. Walker's paraphrased response was that the last time he spoke to the agent in charge (about two years ago) the agent said they no longer had anything on file. Walker concluded from this that it was purged from their system as a non issue. If that is true there is no point in pursuing the FCC for the facts of this situation. All we have are Mr. Walker's statements. That's the basis for my last post.But the important point here is to understand that commercial field strength meters really can accurately measure the radiated fields produced by legal Part 15 systems, and differentiate them from local noise sources -- contrary to earlier posts in this thread. I know they can, because I've done it.

 

[JasonW]

Did you communicate with the FCC Field Office that was involved in this incident? If so, I'm surprised that you didn't reproduce their refutations of William Walker's account of the incident or even mention your communication with them here. Until and unless you do, your claim that Willam Walker's account is "unable to be substantiated in any way other than the postings of Mr. Walker, himself, and/or those who quote him" isn't worth a bucket of warm spit. -- Jason

Before my last post of yesterday, I sent Mr. Walker the following email text about his reported encounter with the FCC. "I understand that this is what you have stated/written, but do you have any means to validate your statements, such as copies of written communications about this from the FCC?"Mr. Walker's paraphrased response was that the last time he spoke to the agent in charge (about two years ago) the agent said they no longer had anything on file. Walker concluded from this that it was purged from their system as a non issue. If that is true there is no point in pursuing the FCC for the facts of this situation. All we have are Mr. Walker's statements. That's the basis for my last post.But the important point here is to understand that commercial field strength meters really can accurately measure the radiated fields produced by legal Part 15 systems, and differentiate them from local noise sources -- contrary to earlier posts in this thread. I know they can, because I've done it.

If you contact that FCC Field Office, you can find out if William Walker was telling the truth about them no longer having the report on the incident. Or maybe you're afraid that they'll find it after a search, so you won't ask them. -- Jason