Radar Field Analyser - RFA641 Edition Date: 28-Feb-18
The Filter control allows you to select between the timing filter options.
• For mode 1,2A/C only radar systems, select the Holdoff mode. In this case the Holdoff control
will become visible. Each time a P1 is counted, a hold off time of 30 µs is started, so that P2 and
P3 can be skipped. It is default set at 30µs, so that no periods between P1 and P2 or P3 are
taken into account.
• For mode-S radar systems, set the filter control to ModeS to only use the mode A/C
interrogation pattern to determine the antenna pattern. In this case the holdoff parameter is
dimmed and omitted.
5. Select the stagger pattern.
• If a repetitive stagger pattern can be found by the software: The pattern and the stagger copy to
the left and right will be shown in the lower graph in blue In that case, the cursors will
automatically be put at the correct positions. In this case, simply click the Return button to
close the Timing window and proceed with section 3.3.3.3. .
• If no pattern can be found automatically: The user must find the repetitive pattern himself: By
selecting a number of periods from the bottom graph and clicking the Copy button, the
stagger pattern is copied into the program’s memory and can be used to extract this radar’s
pulses and discriminate them from other radars. There are two possibilities:
1. If the stagger period is repetitive: Copying this pattern can be done by simply positioning the
two vertical cursors such that they contain a repetitive pattern. Then click the Copy button.
The repetitive pattern between the two cursors will be copied to the left and to the right. This can
be used to check whether the pattern is really repetitive. If it does not fit immediately, try to shift
a cursor one position to the left or right and click the Copy button again.
2. If the stagger period is random (or non-repetitive): In case the pattern is random or non
repetitive, we have to select the complete timing of the boresight, as such that the program can
calculate the minimum and maximum period of the radar. These two values will then be used to
extract the HPD using the Triggered method. This means that each pulse triggers a new
sampling window, which starts at a position Tmin and ends at the occurrence of a new pulse or
at T max. The copying can be done by simply positioning the two vertical cursors such that the
total stagger pattern falls between the two lines. Mirroring the pattern will again take place when
the Copy button is clicked, but obviously the mirrors will not fit the other pattern.
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