- January 28, 2017 at 12:59 am #11070RichParticipant
Total posts : 195
In the areas subject to FCC jurisdiction, only 47 CFR §15.223 permits legal, unlicensed, 1710 kHz radio transmissions for certain conditions — see the clip below.
If the r-f bandwidth of that transmission is ~10 kHz (rather typical for same), then the legal, unmodulated carrier field intensity on 1710 kHz at 30 meters in any direction from the transmit antenna is 15 µV/m.
Just to note that a carrier level of 15 µV/m likely is below the 1710 kHz r-f noise level at almost every receive location in the neighborhood of the general public at/beyond that 30-meter radius. Probably so even for the higher fields closer than 30 meters away.
Legal operation under FCC §15.219 using a carrier frequency of 1700 kHz could produce much greater fields at 30 meters from the transmit antenna, and usefully more far beyond 30 meters.
Therefore it is unclear why anyone would use/advertise 1710 kHz for (legal) AM transmissions on a carrier frequency of 1710 kHz.
§15.223 Operation in the band 1.705-10 MHz.
(a) The field strength of any emission within the band 1.705-10.0 MHz shall not exceed 100 microvolts/meter at a distance of 30 meters. However, if the bandwidth of the emission is less than 10% of the center frequency, the field strength shall not exceed 15 microvolts/meter or (the bandwidth of the device in kHz) divided by (the center frequency of the device in MHz) microvolts/meter at a distance of 30 meters, whichever is the higher level. For the purposes of this section, bandwidth is determined at the points 6 dB down from the modulated carrier. The emission limits in this paragraph are based on measurement instrumentation employing an average detector. The provisions in §15.35(b) for limiting peak emissions apply. …
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