Figure 25 Successful Capture of the Transmit Burst
Time
The horizontal axis of the display represents time. The duration is determined by the impulse
response length of the matched FIR filter.
The same FIR coecients that compute I and Q are used to compute the reference phase
vectors for the burst pulses.
The upper portion of the plot shows the sampling window where the burst pulse is
measured.
On the TTY, the overall time span from the left edge to the right edge is listed as PlotSpan.
Plot
RVP900 computes the power-weighted center-of-mass (COM) of the burst pulse envelope.
This allows the processor to determine the location of the "middle" of the transmitted pulse
within the burst analysis window.
The Pb plot displays small tick marks on the top and bottom of the burst sample window to
indicate the location of the COM. These markers are only displayed when valid burst power
is detected. A second "error bar" is drawn surrounding the tick mark to indicate the
uncertainty of the mark itself. This error interval is used by the burst pulse tracking
algorithm to decide when a timing change can be made with
confidence.
The A/D samples of the IFDR burst input are plotted (somewhat brighter) in the sample
window.
Chapter 6 – Plot-assisted Setups
133
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