Rainbow Electronics TH7899M - Manual (Page 20)

20
TH7899M
2201A–IMAGE–02/02
Preliminary Image
Grade Specifications
Image quality grades are available:
• Grade H, ordering code TH7899MCRH
• Grade T, ordering code TH7899MCRT
• Grade E, ordering code TH7899MCRE
These image quality grades are guaranteed at 25°C and provide a good image for appli-
cations at ambient temperature.
Operating temperature range: 0°C to = 70°C.
Blemish Definition • Column:
It is one pixel in width and
≥
7 pixel high defect whose height is constant with light
level.
• Blemish:
There are usually three types of blemishes:
– White defect, dependent on temperature, as dark signal: its amplitude
doubles for every 8 to 10°C temperature rise.
– Black defect, not dependent on temperature, but whose amplitude is
proportional to the mean output voltage.
White defects are specified in darkness, at +25°C
Black defects are specified under illumination, as a percentage of mean illumination
up to VSAT/2 min independently of temperature.
Traps are specified as defects (white + black) in darkness, at +25°C.
Image Grade
Specifications α
is the amplitude of video signal of blemishes.
Eg: 20% <
α
For amplitude < 20%, pixel is not a blemish.
Z1 is a square area, whose side is half of the height of the image zone, centered in the
image zone.
Z2 is the rest of the image zone.
Image grade is measured on VOS output signal, with 4 outputs operating mode (1s inte-
gration time in darkness, 100 kHz vertical frequency and 5 MHz horizontal frequency).
Illumination conditions: 3200K Halogen lamp + BG38 filter + F/3.5.
H Grade
Z1 Z1 + Z2
Type (White to Black)
White defects in
darkness at 25°C
Defects at VSAT/2
White defects in
darkness at 25°C
Defects at VSAT/2
Pixels affected by blemishes
Area maximum (pixels)
Amplitude
α
30
2x2
150
2x2
α
> 40 mV 20%< |
α
|
α
> 40 mV 20%< |
α
|
Column number maximum
Amplitude
α
0
α
> 2 mV
0
10% < |
α
|
0
α
> 2 mV
0
10% < |
α
|