Yaesu FT-991 Operating Manual page 40

c
onvenience
AMS ( A
The transceiver has the AMS (Automatic Mode Select) function which enables the transceiver to automatically select
the most appropriate option out of the three communication modes according to the received signal while operating in
C4FM mode.
Besides C4FM digital signals, analog signals (FM) are also identified in order to automatically match the communica-
tion mode of the partner station.
n :
ote
The AMS function recognizes the three modes listed in the following table. Other communication modes cannot be rec-
ognized.
o M
perAting ode
V/D mode
(simultaneous voice and data
communication mode)
Voice FR mode
(Voice full-rate mode)
Analog FM mode
1. Press the MODE button, and then touch the corre-
sponding key on the LCD to select the C4FM operat-
ing mode. The "C4FM" icon appears in the display.
Press the MODE button once more.
2. Touch [ AMS ] on the LCD. The AMS function will
switched to "ON" and the communication mode will
be switched to match the received signal.
Page 38
f
eatures
M
utoMAtic ode
d
iSplAy
DN
When AMS is "ON": Red
When AMS is "OFF": Light blue
VW
When AMS is "ON": Red
When AMS is "OFF": Light blue
AN
Only when AMS is "ON": Lights red
) o
S
elect perAtion
e
xplAnAtion oF
As the audio signal error is detected and repaired at the
same time as the transmission of the digital audio signal,
it becomes more difficult for conversations to be cut off. A
basic digital mode of C4FM FDMA.
Digital voice data is transmitted using the entire 12.5 kHz
bandwidth. High quality voice communication is possible.
Analog communication mode using the FM mode.
This mode is effective for communication when the signal
strength is so weak that the voice is cut off midway in the
digital mode.
MODE Button
n :
ote
In the V/D mode ("DN" displayed), the position infor-
mation is included in the transmitted signal during the
conversation, but in the Voice FR mode ("VW" dis-
played), the position information is not included.
FT-991 O
M
odeS
M
peraTing anual