USER’S MANUAL__________________________________________________________________
40 __________________________________________________________________ M211322EN-D
algorithm does a coarse search for the burst pulse in the time/frequency
domain (by scanning the AFC). It then does a fine search, in both time and
frequency, to assure that the burst is centered at “range 0” and is at the
required IF value. The power-weighted phase of the burst pulse and the
total burst pulse power is computed. The power-weighted average phase is
used to make the digital phase correction. Phase jitter for magnetron
systems, with good quality modulator and STALO, is better than 0.5
degrees RMS, as measured on actual nearby clutter targets. For Klystron
systems, the phase locking is better than 0.1 degree RMS.
The burst pulse frequency is also analyzed to calculate the frequency error
from the nominal IF frequency. For magnetron systems, the error is filtered
with a selectable time constant, which is typically set to several minutes to
compensate for slow drift of the magnetron. The digital frequency error is
sent through the uplink to the IFDR in the receiver cabinet.
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