Tektronix 1740A Series, Руководство пользователя

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Glossary
Glossary–4
1740A/1750A/1760 – Series Service Manual
Gamma (NTSC) Since picture monitors have a nonlinear relationship between
the input voltage and brightness, the signal must be correspondingly predis-
torted. Gamma correction is always done at the source (camera) in television
systems: the R, G, and B signals are converted to R
1
/
V
, G
1
/
V
, and B
1
/
V
. Values
of about 2.2 are typically used for gamma.
Gamma (PAL)
Since picture monitors have a nonlinear relationship between
the input voltage and brightness, the signal must be correspondingly predis-
torted. Gamma correction is always done at the source (camera) in television
systems: the R, G, and B signals are converted to R
1
/
V
, G
1
/
V
, and B
1
/
V
. Values
for gamma range from 2.2 to 2.8.
Gamut
See Color Gamut.
GBR The same signals as RGB, but rearranged in sequence to correspond with
SMPTE specification.
Gen Lock
The process of locking both sync and burst of one signal to sync and
burst of another, making the two signals completely synchronous.
Graticule The scale which is used to quantify the information on a waveform
monitor or vectorscope display. Graticules may either be screened onto the
faceplate of the crt itself (internal graticule), or onto a piece of glass or plastic
which fits in front of the crt (external graticule). They can also be electronically
generated.
Horizontal Blanking
Horizontal blanking is the entire time between the end
of the active picture time of one line and the beginning of active picture time of
the next line. It extends from the start of front porch to the end of backporch.
Horizontal Sync
Horizontal sync is the –40 IRE pulse in NTSC systems
(–300 mV pulse for PAL systems) occurring at the beginning of each line. This
pulse signals the picture monitor to go back to the left side of the screen and
trace another horizontal line of picture information.
Hue
Hue is the property of color which allows us to distinguish between colors
such as red, yellow, purple, etc.
Hum Hum refers to the undesirable coupling of the 60 Hz power sine wave for
NTSC systems (50 Hz power sine wave in PAL systems) into other electrical
signals.
ITS (PAL)
Insertion Test Signal. A test signal which is inserted in one line of
the vertical interval to facilitate in-service testing.
IRE (NTSC) A unit equal to 1/140 of the peak-to-peak amplitude of the video
signal, which is typically 1 volt. The 0 IRE point is at blanking level, with sync
tip at –40 IRE and white extending to +100 IRE. IRE stands for Institute of
Radio Engineers, the organization which defined the unit.
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