47 CFR § 90.207 - Types of emissions.
Unless specified elsewhere in this part, stations will be authorized emissions as provided for in paragraphs (b) through (n) of this section.
(a)Most common emission symbols. For a complete listing of emission symbols allowable under this part, see § 2.201 of this chapter.
(1) The first symbol indicates the type of modulation on the transmitter carrier.
(2) The second symbol indicates the type of signal modulating the transmitter carrier.
(3) The third symbol indicates the type of transmitted information.
(b) Authorizations to use A3E, F3E, or G3E emission also include the use of emissions for tone signals or signaling devices whose sole functions are to establish and to maintain communications, to provide automatic station identification, and for operations in the Public Safety Pool, to activate emergency warning devices used solely for the purpose of advising the general public or emergency personnel of an impending emergency situation.
(c) The use of F3E or G3E emission in these services will be authorized only on frequencies above 25 MHz.
(d) Except for Traveler's Information stations in the Public Safety Pool authorized in accordance with § 90.242, only J3E emission will be authorized for telephony systems on frequencies below 25 MHz.
(e) For non-voice paging operations, only A1A, A1D, A2B, A2D, F1B, F1D, F2B, F2D, G1B, G1D, G2B, or G2D emissions will be authorized.
(i) For telemetry operations, when specifically authorized under this part, only A1D, A2D, F1D, or F2D emissions will be authorized.
(l) For stations in the Public Safety and Industrial/Business Pools utilizing digital voice modulation, in either the scrambled or unscrambled mode, F1E or G1E emission will be authorized. Authorization to use digital voice emissions is construed to include the use of F1D, F2D, G1D, or G2D emission subject to the provisions of § 90.233.
(n)Other emissions. Requests for emissions other than those listed in paragraphs (c) through (e) of this section will be considered on a case-by-case basis to ensure that the requested emission will not cause more interference than other currently permitted emissions.