请教高人:电波型式F2D和F3E是指什么?

(1) The first symbol indicates the type of modulation on the transmitter carrier.
A—Amplitude modulation, double sideband with identical information on each sideband.
F—Frequency modulation.
G—Phase modulation.
J—Single sideband with suppressed carrier.
P—Unmodulated pulse.
W—Cases not covered above, in which an emission consists of the main carrier modulated, either simultaneously or in a
pre-established sequence, in a combination of two or more of the following modes: amplitude, angle, pulse.
(2) The second symbol indicates the type of signal modulating the transmitter carrier.
0—No modulation.
1—Digital modulation, no subcarrier.
2—Digital modulation, modulated subcarrier.
3—Analog modulation.
(3) The third symbol indicates the type of transmitted information.
A—Telegraphy for aural reception.
B—Telegraphy for machine reception.
C—Facsimile.
D—Data, telemetry, and telecommand.
E—Voice.