campbell@sol.cs.wmich.edu (Paul Campbell) (06/21/91)
I am interested in low power unlicensed transmitters, but the local library is all over the city and rather inaccessible (they are renovating the main campus library). Is there an FCC site where I can get a copy of part 15? How much would the FCC charge for such a document? All I really need to know is (relatively speaking) the best band to transmit an FM or AM signal at a range of about 500-1000 feet legally, so I'd be looking at FM most likely and somewhere around 500 uV/m with a fairly good amplifier at the other end. Longer distances (1000-2000 feet) would be a real plus, but that sounds so nice that I'd never expect that out of the FCC, though I have heard that they don't fuss too much if you use an unused section of the band and keep it down to under 1 mile. Someone even claimed that in certain bands, you can transmit up to 100 mW without a problem?!?
bill@thd.tv.tek.com (William K. McFadden) (06/22/91)
Here are some of the regulations from CFR 47 Ch. 1 (10-1-89 edition) Part 15. 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 Field strength Measurement distance (MHz) (microvolts/meter) (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 15.219 Operation in the band 510-1705 kHz. (a) The total input power to the final radio frequency stage (exclusive of filament or heater power) shall not exceed 100 milliwatts. (b) The total length of the transmission line, antenna, and ground lead (if used) shall not exceed 3 meters. (c) All emissions below 510 kHz or above 1705 kHz shall be attenuated at least 20 dB below the level of the unmodulated carrier. Determination of compliance with the 20 dB attenuation specification may be based on measurements of the intentional radiator's antenna output terminal unless intentional radiator uses a permanently attached antenna, in which case compliance shall be demonstrated by measuring the radiated emissions. 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. There are additional bands for which exceptions to 15.209 exist. They are summarized below. See CFR 47 for special restrictions applying to the use of these bands. Frequency Fld. strength/ Meas. Distance/ FCC Primary or (MHz) Input power Antenna length Par. Designated use 0.16-0.19 1 W 15 m (antenna) 15.217 Hobby (Lowfer) 0.510-1.705 100 mW 3 m (antenna) 15.219 AM Broadcast 1.705-10 100 uV/m 30 m 15.223 Spread spectrum? 13.553-13.567 10 mV/m 30 m 15.225 ? 26.96-27.28 10 mV/m 3 m 15.227 CB 40.66-40.70 1 mV/m 3 m 15.229 Cordless phones 49.82-49.90 10 mV/m / 100mW 3 m 15.235 Toys, cordless phones 72-73 80 mV/m 3 m 15.237 Auditory assistance, RC 75.4-76.0 80 mV/m 3 m 15.237 Auditory assistance, RC 88-108 250 uV/m 3 m 15.239 FM broadcast 174-216 1.5 mV/m 3 m 15.241 Microphones?, TV 7-13 890-940 N/A N/A 15.243 Spread spec., VCR xmtr? My photocopy of the regulations ends just after the beginning of 15.243, so I can't provide any information about the 890-940 MHz or any higher band. -- Bill McFadden Tektronix, Inc. P.O. Box 500 MS 58-639 Beaverton, OR 97077 bill@tv.tv.tek.com, ...!tektronix!soul!bill Phone: (503) 627-6920 "How can I prove I am not crazy to people who are?"