TB 9-6625-2309-24
(11) Adjust CURSOR A control as necessary to position cursor A on FOCUS
GENERATED PULSE AT LEADING EDGE STARTING POINT (fig. 5).
Figure 5. Example of cursor A on FOCUS GENERATED PULSE LEADING EDGE STARTING POINT (TD-260C).
NOTE
Accurate cursor placement to correct position on pulse starting
point is required for good results. Some optical modules have
been observed to display undershoot on trace prior to FOCUS
pulse. If there is undershoot, adjust cursor to immediate
beginning of FOCUS generated pulse after undershoot so
undershoot is just below horizontal center graticule (fig. 6).
(12) Record A= (in km) on TI display in A= (km) column on TD-260C Horizontal Scale
Data Sheet (appendix A).
NOTE
Each change in digital delay/pulse generator A= T+ value will
not produce a change in position of FOCUS generated pulse.
Normally a series of A= T+ values, incremented in small
constant positive steps, will result in same pulse positions up to
a point. At this point the next A=T+ increment will cause pulse
to shift to right of the cursor on TI display. This procedure
requires the lowest A=T+ value which causes the FOCUS
generated pulse to shift in position, resulting in a larger A= T+
indication. One shift is required for each cluster of data. When
this shift occurs, no more data is required for that cluster.
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