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1	Frequently Asked Questions: Velocity Profile Pieces What if I reset the Blank too short? How Close to the Bottom can I measure? How Shallow can I measure? What is the effect of loud scatterers heard thru Sidelobes?
2	What if I reset the BLANK too short? Next 2 pages
3	If the BLANK is reset too short, the first good depth cell moves out a distance of one cell. If acoustic ringing persists, even briefly, into the time slot of the first range gate, the resulting velocity computation is biased low. TIP: Using small depth cells limits the fraction of the velocity profile degraded, if the blank size is reset to be too short.
4	Blank Too Short (Figure)
5	How close to the Bottom can I measure? Next 3 pages
6	Sidelobe Layer at Boundary (Figure)
7	Sidelobe Bias (Figure)
8	Depth of First Unbiased Cell ADCP end of profile First unbiased cell is at Blank depth + ONE Depth Cell* or c/2 x (1/2 Range Gate + blank + 1/2 transmit duration) default Boundary end of profile First unbiased cell lies above 6% sidelobe depth + ONE Depth Cell or c/2 x (1/2 Range Gate + 6% sidelobe + 1/2 transmit duration) TIP: Setting small depth cells is the primary means to measure (1) closer to boundaries or (2) more of a given water depth.
9	How Shallow can I measure? Working Rule for Shallowest Depth when Working from a Boat (using N depth cells) (2+N) x Depth Cell size PLUS LARGER of either (1) 30 cm OR (2) 4 x ADCP immersion depth
10	How shallow? (Figure)
11	What is the effect of loud scatterers heard thru Sidelobes? Next 2 pages
12	Energy Out/In Thru Sidelobe
13	Energy Out Via Adjacent Beam/In Thru Sidelobe