WiNRADiO G33DDC HF Receiver
38
AMS Mode
The
AMS
mode is used to improve reception quality of amplitude-modulated
signals, especially those affected by selective fading which occurs over a large
distance.
When the AMS mode is selected, special controls appear under the tuning tab,
making it possible to select one (or both) of the signal’s sidebands to achieve
optimum reception:
In the AMS mode, there is a certain "capture range", a frequency range within
which the receiver will "capture" the signal and achieve synchronization. If you
are tuning to a new signal, this
initial capture (“
Tune capture range
”) is initially
quite wide, within plus or minus 1.5 kHz (default value) from the actual signal
frequency, to enable easy tuning by pointing and clicking near the peak in the
DDC spectrum, or dragging the filter passband area in the demodulator
spectrum.
Once locked to a signal, the capture range automatically reduces
(“
Sync. lock
range
”) to plus or minus 50 Hz (default value) from the signal frequency. The
reason for such reduction is to avoid “kidnapping" of the synchronization
frequency by a nearby strong signal if the carrier signal fades, as may happen
especially with long-distance reception, due to ionospheric effects.
Both the
Tune capture range
and the
Sync. lock range
values are user-
definable, under the
Options | AMS capture range
menu.
When the signal is locked in synchronization, this is indicated using a "lock"
symbol located in the top left corner of the frequency display:
