87.9 MHz NOUO, did the agent get it wrong?

There is one definite station licensed at 87.9 and I recall seeing a list of new LPFMs that will be on that channel:

http://www.radio-locator.com/info/KSFH-FM

For licensed stations it is possible to be on 87.9, but unless the part 15 intentional radiator rules have changed since oet63rev was put out, I think the inspector applied the wrong standard in the NOUO.

Intentional radiation (continuous transmission) is not permitted in TV channels (54-72, 76-88, 176-216, 470-806). 87.9 “belongs” to TV channel 6.

So I think the inspector should have cited them for violating 15.231 (a) “[…] Continuous transmissions, voice, video and the radio control of toys are not permitted. […]”. Field strength should not have mattered for that NOUO.

So the signal on 87.9 should have received a NOUO, but I think the issued NOUO was wrong.

(This is funny to me because an inspector applying 250 uv/m at 3m to 87.9 MHz is like a broadcaster trying to apply 100mW into a 3m antenna/ground at 1710 kHz).

I see your point, stvcmty, the part 15 rules would need to be re-written to include 87.9 along with 88 - 108 MHz.

Here's another baffler for you...

I have an FCC certified Scosche FM transmitter that includes 87.7 and 87.9 MHz.

It's like traffic signs saying ONE-WAY, DEAD END, NO LEFT TURN, NO RIGHT TURN, NO U-TURN.

Like Carl I have seen FCC Certified devices for 87.9.  Probably an old error in the writing of FCC Rules.  They are full of errors, contradictions and omissions.  The rules are "designed" that way.  88-108 is the way the FM band is specified, though 87.9 is FM Channel 200. I have also seen NOUO's for 87.9 calling out the 250 uV/M rule many times. So based on the 'secret" book, 87.9 is "probably" OK for Part 15 operation or the above mentioned devices would not be certified.

Agreeing with John WDCX, himself in good sitting with the ALPB... that's... good standing....

Using 87.9 MHz is probably legal.

87.7 MHz might also be legal.

There's a good chance some things might be legal that we don't realize.

I feel legal, how do you feel?

You seem legal to me.

Let's act legal and see where we get.

Don't the rules state something about attenuating the signal if the part 15 transmitter operates below the fm band? Anything above 107.9 would be totally illegal considering that is the aircraft band in America.

Edit: I answered my own question....

§15.239   Operation in the band 88-108 MHz.

(a) Emissions from the intentional radiator shall be confined within a band 200 kHz wide centered on the operating frequency. The 200 kHz band shall lie wholly within the frequency range of 88-108 MHz.

(b) The field strength of any emissions within the permitted 200 kHz band shall not exceed 250 microvolts/meter at 3 meters. The emission limit in this paragraph is based on measurement instrumentation employing an average detector. The provisions in §15.35 for limiting peak emissions apply.

(c) The field strength of any emissions radiated on any frequency outside of the specified 200 kHz band shall not exceed the general radiated emission limits in §15.209.

(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 information:

(1) 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.

[54 FR 17714, Apr. 25, 1989; 54 FR 32340, Aug. 7, 1989]

I goofed...
§15.209   Radiated emission limits; general requirements.

(a) Except as provided elsewhere in this subpart, the emissions from an intentional radiator shall not exceed the field strength levels specified in the following table:

Frequency (MHz)    Field strength (microvolts/meter)    Measurement distance (meters)
0.009-0.490    2400/F(kHz)                                        300
0.490-1.705    24000/F(kHz)                                      30
1.705-30.0    30                                                       30
30-88    100**                                                          3
88-216    150**                                                        3
216-960    200**                                                      3
Above 960    500                                                     3

**Except as provided in paragraph (g), fundamental emissions from intentional radiators operating under this section shall not be located in the frequency bands 54-72 MHz, 76-88 MHz, 174-216 MHz or 470-806 MHz. However, operation within these frequency bands is permItted under other sections of this part, e.g., §§15.231 and 15.241.

(b) In the emission table above, the tighter limit applies at the band edges.

(c) The level of any unwanted emissions from an intentional radiator operating under these general provisions shall not exceed the level of the fundamental emission. For intentional radiators which operate under the provisions of other sections within this part and which are required to reduce their unwanted emissions to the limits specified in this table, the limits in this table are based on the frequency of the unwanted emission and not the fundamental frequency. However, the level of any unwanted emissions shall not exceed the level of the fundamental frequency.

(d) The emission limits shown in the above table are based on measurements employing a CISPR quasi-peak detector except for the frequency bands 9-90 kHz, 110-490 kHz and above 1000 MHz. Radiated emission limits in these three bands are based on measurements employing an average detector.

(e) The provisions in §§15.31, 15.33, and 15.35 for measuring emissions at distances other than the distances specified in the above table, determining the frequency range over which radiated emissions are to be measured, and limiting peak emissions apply to all devices operated under this part.

(f) In accordance with §15.33(a), in some cases the emissions from an intentional radiator must be measured to beyond the tenth harmonic of the highest fundamental frequency designed to be emitted by the intentional radiator because of the incorporation of a digital device. If measurements above the tenth harmonic are so required, the radiated emissions above the tenth harmonic shall comply with the general radiated emission limits applicable to the incorporated digital device, as shown in §15.109 and as based on the frequency of the emission being measured, or, except for emissions contained in the restricted frequency bands shown in §15.205, the limit on spurious emissions specified for the intentional radiator, whichever is the higher limit. Emissions which must be measured above the tenth harmonic of the highest fundamental frequency designed to be emitted by the intentional radiator and which fall within the restricted bands shall comply with the general radiated emission limits in §15.109 that are applicable to the incorporated digital device.

(g) Perimeter protection systems may operate in the 54-72 MHz and 76-88 MHz bands under the provisions of this section. The use of such perimeter protection systems is limited to industrial, business and commercial applications.

[54 FR 17714, Apr. 25, 1989; 54 FR 32339, Aug. 7, 1989; 55 FR 18340, May 2, 1990; 62 FR 58658, Oct. 30, 1997]

Still yet, if this station was above the limit i can see why it was busted. I couldn't find exactly what i wanted out of the fcc rules, seems my memory is a bit fuzzy but i thought at one point there was a -40 dB attenuation limit for use outside of the fm band.

This NOUO for 87.9 looks right:
http://transition.fcc.gov/eb/FieldNotices/2003/DOC-332701A1.html Of note “In addition, fundamental emissions from intentional radiators operating under Part 15 shall not be located in the frequency band 76-88 MHz.”

The frequencies below 88 FM are tempting just like AM 1710 is tempting because they occur on most radios.

The notice posted above that "part 15 fundamental emissions are not allowed between 76 - 88 MHz" means something to me because I have an FCC Certified Scosche Transmitter that covers 87.5, 87.7 and 87.9, but it must be a mistake, I guess.

No time to take chances in today's collapsing world, I'll stay off those channels.

The ALPB is the hope and promise of tomorrow.

Are allowed in the 76-88 MHZ range under Part 15.

Now that John WDCX mentions it, I have a faded memory about an FCC paper describing a waiver for using wireless mics from 76 to 88 MHz.

This may be wrong, but I think they are allowed 50 mW!

So, you run a radio station and call it... "You are listening to Wireless Microphone Station WDCX down here in Florida or wherever this is."

It's the Part 15 version of a "Franken Station" (TV Channel 6 used as an FM station).

To even think about using a wireless microphone to make a “Franken -part 15” FM station, there are some important things to do:

1. Check the spacing to the closest TV station licensed on channel 6. If you are in the north east (FCC TV Zone I) and there is a licensed TV station on channel 6 within 65 miles from you, stay out of 82-88MHz. If you are anywhere else (FCC TV Zone 2), and there is a channel 6 TV station within 80 miles from you, stay out of 82-88MHz. (I think that requirement would put many locations out of luck, there are a few full power DTV channel 6’s, some LP/Translator DTV 6’s, and a bunch of analog 6 Franken FM’s. http://www.rabbitears.info/allocationmap.php?circoc=129&ciradj=0&channel=6&adj=N&all=Y [that is just digitals])
2. Setup a “fixed device” that receives your “wireless microphone” intentional radiation. There is some language about wireless microphones being used to send audio to a fixed device. If you don’t have a fixed device receiving the transmission from your wireless microphone then it is going to be hard to explain you operate under wireless microphone rules and not failing to operate under 15.239.
3. Make sure your wireless microphone is on a proper frequency “The frequency selection shall be offset from the upper or lower band limits by 25 kHz or an integral multiple thereof.”
Further reading:
http://www.fcc.gov/encyclopedia/wireless-microphones
https://apps.fcc.gov/edocs_public/attachmatch/FCC-10-16A1.pdf
https://apps.fcc.gov/edocs_public/attachmatch/DA-10-92A1.pdf
https://apps.fcc.gov/edocs_public/attachmatch/FCC-14-145A1.pdf
https://apps.fcc.gov/edocs_public/attachmatch/FCC-14-144A1.pdf