47 CFR 90.221: Adjacent channel power limits.

(a) For the frequency bands indicated below, operations using equipment designed to operate with a 25 kHz channel bandwidth may be authorized up to a 22 kHz bandwidth if the equipment meets the adjacent channel power (ACP) limits below. The table specifies a value for the ACP as a function of the displacement from the channel center frequency and a measurement bandwidth of 18 kHz.

(b)(1) Maximum adjacent power levels for frequencies in the 450-470 MHz band:

Frequency offset Maximum ACP (dBc) for devices 1 watt and less Maximum ACP (dBc) for devices above 1 watt

25 kHz −55 dBc −60 dBc

50 kHz −70 dBc −70 dBc

75 kHz −70 dBc −70 dBc

(2) In any case, no requirement in excess of −36 dBm shall apply.

(c)(1) Maximum adjacent power levels for frequencies in the 809-824/854-869 MHz band:

Frequency offset Maximum ACP (dBc) for devices less than 15 watts Maximum ACP (dBc) for devices 15 watts and above

25 kHz −55 dBc −55 dBc

50 kHz −65 dBc −65 dBc

75 kHz −65 dBc −70 dBc

(2) In any case, no requirement in excess of −36 dBm shall apply.

(d) On any frequency removed from the assigned frequency by more than 75 kHz, the attenuation of any emission must be at least 43 + 10 log (Pwatts) dB.