Wavecom W-SPECTRA (Automatic Monitoring System) V1.1.0 - Manual (Page 57)

WAVECOM Monitoring System W-SPECTRA, W-SPEED Manual V1.1.0 Parameters and Options
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A separate window to display the result.
Auto
By setting the “auto-mode” to “on” the mode parameters “shift”, “center” and “baudrate” are automatical-
ly calculated and adjusted. After the recalculation the “auto-mode” goes to “off”.
Modulation
In the Modulation pull-down list the user may set the demodulator of a mode decoder.
Most HF, VHF or UHF modes feature a pre-selected demodulator mode for optimum performance, but
sometimes different demodulators may be chosen.
AM
Satellite weather charts are transmitted using AM. This demodulator uses the quadrature I/Q demodula-
tion method.
The level displayed by the level indicator corresponds to the AM modulation depth of the signal.
BPSK
BPSK shifts the carrier phase ±180 degrees. For carrier recovery a Costas loop is used - this is a PLL with
a special phase comparator, which removes the payload data from the PLL loop. The input signal is then
down-converted to base band by mixing the carrier in a complex mixer, and the resulting signal is the da-
ta signal.
BPSK is almost exclusively used for satellite data links.
CW
The CW demodulator utilizes a steep, adaptive band pass filter and automatic amplitude control. The AGC
attack time may be adjusted according to the propagation conditions. The filter response may be set to
Slow, Normal or Fast. This demodulator produces high quality CW decoding. It is important to select the
appropriate receiver AGC response (normal or slow).