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V1642OM.DOC
17 February, 2005
3. OPERATION
3.1 ADJUSTMENT
RANGES
The adjustment ranges on the main parameters are:
PARAMETER RANGE
Video Gain
±
6dB
Chroma Gain
±
6dB (aggregate)
Black Level
±
100 levels (~100mV)
De-Hanover bar
ON (
σ
) or
OFF (
τ
)
Hue Shift
±
45
°
Since the chrominance components are subject to both the video and chroma gains the two are
compounded. However the overall gain limit is still
±
6dB.
Since the control system does the gain compounding, there is no loss of signal integrity. For example a
video gain of +3dB and a chroma gain of -3dB will have no effect on the chrominance components at all,
so there will be no limiting or loss of resolution.
3.2 HUE
SHIFT
&
DE-HANOVER
BAR
In general the Hue Shift is more useful in NTSC areas which generally use 525/60 D1 signals, and
conversely the De-Hanover Bar function is more useful for PAL areas which use 625/50 D1 signals.
Thus the fourth front panel function defaults this way.
However this may not be the case so switches have been provided to enable the alternate function for
either format. This only applies to local front panel control. With either remote control all functions are
available in all formats.
FORMAT SWITCH CONTROL
625/50
LK4.0 ON
De-Hanover Bar
LK4.0 OFF
Hue Shift
525/60
LK4.1 ON
Hue Shift
LK4.1 OFF
De-Hanover Bar
3.3 FUNCTION
ORDER
The Black Level offset is applied before the gain stages. This is considered the best arrangement when
the offset is used to correct for an incorrect input, such as may occur with poor quality input signals.
3.4 DYNAMIC
ROUNDING
Since some quantising effects may be visible on the output of this unit when variable gains are applied,
Dynamic Rounding has been applied. This can be disabled by switching LK4.3 to OFF.
3.5 LIMITING
Since gain can be applied to the D1 signal it is possible to generate levels outside the normal 10 bit
gamut of D1 and so limiting is required. The V1642 normally applies a soft form of limiting that
progressively reduces the gain of a signal as it approaches the limits, either overshoot or undershoot. If
this is not required then it can be disabled by putting LK4.2 to OFF.
The limiting that is applied is ‘simple’ in that it does not ensure that the output is correctly within the
colour gamut, but only that each of the three components remain within the legal 10 bit range.
