WHAT HAPPENS DURING VELOCITY ALIASING
AND RANGE FOLDING
 
METEOROLOGIST JEFF HABY
Suppose the maximum unambiguous velocity is 30 m/s. If the wind is blowing at 35 m/s, the radar will show
the 35 m/s wind as a 5 m/s wind instead. All wind speeds above 30 m/s will be aliased in this case. Computer
algorithms can correct this aliasing or increasing the PRF can correct this aliasing.
Suppose the maximum unambiguous range is 200 kilometers. If a storm is located at 225 kilometers from the radar,
the radar will detect the storm as being 25 kilometers from the radar instead. Any energy returned to radar
beyond 200 kilometers would be range folded. This occurs because the radar energy bounced off the distant
storm is returning to the radar after the radar has already sent out another pulse and is "listening" for
return echoes. Decreasing the PRF can correct this problem.


