DGA-6000 ULTRA-HD VIDEO GENERATOR / ANALYZER USER MANUAL
B-5
Units
– The unit for each cursor value is shown just below each cursor value whenever Cursors are
enabled. The Units menu item and the cursor units are not displayed when the Cursors are Off. Use the Left
and Right cursor keys to change the resolution and frequency units whenever Units is highlighted in green.
Four (4) sets of units are selectable.
Spatial Resolution Units
Cursor
Rh
Rv
Rr
Units (set 1)
L/PW
L/PH
L/PW
Units (set 2)
TVL
TVL
TVL
Spatial Frequency Units
Cursor
Fh
Fv
Fr
Units (set 3)
%Nyq %Nyq %Nyq
Units (set 4)
C/PW
C/PH
C/PW
Cursor Labels
Rh, Rv, Rr = Horizontal, vertical, and radial spatial resolution cursors
Fh, Fv, Fr = Horizontal, vertical, and radial spatial frequency cursors
Resolution Units
L/PW = Lines per Picture Width
L/PH = Lines per Picture Height
TVL = TV Lines (L/PH)
Frequency Units
%Nyq = % of Nyquist Frequency
C/PW = Cycles per Picture Width
C/PH = Cycles per Picture Height
Notes:
1) Effective video resolution is numerically the maximum TOTAL number of light and dark lines that can
be individually discerned per picture width or picture height. This differs from photography where image
and lens resolution is usually stated in terms of line-pairs rather than total lines.
2) TVL (TV Lines) is the traditional unit for specifying effective display resolution for both horizontal and
vertical resolution. TVL is equivalent to L/PH. The horizontal spatial resolution in TVL (L/PH) is therefore
the L/PW divided by the display aspect ratio (16/9 = 1.777 for HD).
3) The Nyquist spatial frequency is the absolute maximum spatial frequency that can be represented in
an image and is therefore equivalent to one-half of the spatial sampling rates. The horizontal Nyquist
frequency is one-half the total Pixels/PW. The vertical Nyquist frequency is one-half the total Lines/PH.
Selecting Cursor Span (GEN-Zero)
– Cursor values increase as the cursors move in any direction
away from the pattern origin (you can set the cursors to the origin by pressing the Func-Zero key
sequence). When the cursors reach the Nyquist Frequency the values then decrease until the cursor
reaches the Sampling Frequency location (twice the Nyquist Frequency). This matches the displayed
cursor values to the image spatial frequencies (in the absence of aliasing frequencies). See the
discussion of Frequency Replication & Aliasing
in the Technical Concepts section of this manual.
The span of the cursor values can be doubled to twice the Nyquist Frequency by pressing the GEN-
Zero key sequence. This may be helpful for understanding the Frequency Replication concept. Press
the GEN-Zero key sequence again to restore the default single Nyquist Frequency cursor values span.
