47 C.F.R. § 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 (P