Category : Science and Education
Archive   : FREQTEXT.ZIP

Output of file : EMISSONS.TXT contained in archive : FREQTEXT.ZIP

³ Guide to FCC-Defined Radio Emissions ³
Type Notes
---- -----
A2 Amplitude Modulated telegraphy #1,2
A3 DSB (full carrier telephony)
A3A SSB (reduced carrier telephony)
A3B (2 independent sidebands -
reduced carrier) #3
A3J SSB (supressed carrier telephony)
A4 DSB facsimile
A4A SSB facsimile, reduced carrier
A4J SSB facsimile, supressed carrier
A5 DSB television
A5C VSB television #4

(Frequency modulation)

F0 carrier - no modulation
F1 frequency shift telegraphy #1
F2 frequency modulated telegraphy #1,2
F3 telephony
F4 facsimile
F5 television


1. This is not restricted to Morse - may be RTTY, for example.
(RTTY could be run on 160 meters if on-off keying of
the carrier is used).

2. Examples of this mode are: 1) Carrier keyed on/off
2) carrier on with the modulation keyed on/off 3)
carrier on with the modulation frequency shift keyed.

3. This is used by short wave broadcast station studio to
transmitter links with separate programs on each set
of sidebands.

4. VSB = Vestigial sideband where all of one set of side-
bands is transmitted but only about 20 percent of the other
set of sidebands is transmitted (the lowest frequencies).

Common Amateur emissions:

Double sideband voice = 6A3
Single sideband voice = 3A3J
VHF FM voice = 16F3
25 wpm Morse cw = .1A1

(assume max modulating freq of 3KHz and max deviation of

Bandwidths are found with the following formulae:

A1 Bw = BK K=5 for fading circuits)
A2 Bw = BK+2M
A3 Bw = 2M
A3J Bw = M
A4 Bw = KN+2M (K=1.5)
F1 Bw = 2.6D+.55B (when 2D/B is less than 5.5)
Bw = 2.1D+1.9B (when 2D/B is greater than 5.5)
F3 Bw = 2M+2DK (K=1)
F4 Bw = KN+2M+2D (K=1.5)


Bw = necessary bandwidth in Hz
B = speed in bauds
C = subcarrier freq. in Hz
D = 1/2 the diff. between max and min instantaneous
freq (in other words, peak deviation).
K = fudge factor
M = maximum modulating freq. in Hz
N = maximum black & white elements per second
(N = drum circumference x lines per unit length
x drum rps)

As a result of WARC 79, the very familiar symbols of the
emissions modes will be changed. The FCC will be implementing
the following new symbols over the next several years.

Old Symbol New Symbol Old Symbol New Symbol

A0 N0N F0 N0N
A1 A1A F1 F1B
A2 A2A F2 F2A
A2J J2A F3 F3E
J2D F4 F3C
A3 A3E F5 F3F
A4 A3C
A5 C3F

Symbol Explanation:
First character indicates emission type
Second character indicates the nature of the signal
Third character indicates the type of information transmitted

First Character
N = Unmodulated carrier
A = Double sideband AM
J = Single sideband, suppressed carrier
F = Frequency modulation
P = Sequence of unmodulated pulses
C = Vestigial sidebands

Second Character
0 = No modulating signal
1 = Single channel containing digital information without the
use of a modulating subcarrier
2 = Same as above, except using a modulating subcarrier
3 = Single channel containing analog information

Third Character
N = No information transmitted
A = Telegraphy -- aural reception
B = Telegraphy -- automatic reception
C = Facsimile
D = Data transmission, telemetry, telecommand
E = Telephony
F = Television

Example: A1A is double sideband, single channel containing
digital information without the use of a modulating
subcarrier, telegraphy for aural reception. In other
words, CW!

  3 Responses to “Category : Science and Education
Archive   : FREQTEXT.ZIP

  1. Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!

  2. This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.

  3. But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: