Wavecom W61PC V7.5.0 - Manual (Page 90)

80  Analysis Tools WAVECOM Decoder W61PC/LAN Manual V7.5
PSK Symbol Rate (HF, DIR, SUB, SAT)
When starting PSK signal analysis, one is trying to determine the characteristics of an unknown signal.
The normal starting point for this is the FFT.
The FFT is used to determine an estimate of the signal center frequency and signal bandwidth. This should
be done by adjusting the measurement cursors. The phase analysis tools inherits the information deter-
mined by the measurement cursors, and uses this information to configure the center frequency and
bandwidth. This in turn sets up a pre-filter, allowing the tools to be used for signals disturbed by out-of-
band interference, or when more concurrent channels are present.
To determine the symbol rate, a PSK symbol rate analysis tool is provided. This tool provides a spectrum
display (with three zoom levels) and allows the measurement of the symbol rate using cursors. A PSK sig-
nal will normally produce multiple peaks. Normally (but not always) the symbol rate (or baud rate) will be
a distinct peak at the highest amplitude. The other peaks are normally fractions of the true symbol rate.
Zoom
For signals with low symbol rates, select a different zoom factor by using the menu which appears when
right-clicking the display. Note that the lower scales have a higher precision, but at the expense of a lower
display rate.
Filter
The filter adjusts the smoothing filtering applied to the display. Depending on the signal data content, it
may be found that more filtering is required to clearly observe the peaks.