SAA4970T/V2 Ver la hoja de datos (PDF) - Philips Electronics

Número de pieza

componentes Descripción

Fabricante

SAA4970T/V2

Economical video processing IC (ECOBENDIC)

Philips Electronics 

Philips Semiconductors

Economical video processing IC

(ECOBENDIC)

Preliminary specification

SAA4970T

PEAKING

Peaking is implemented to obtain a higher gain in the

middle and upper ranges of the luminance bandwidth.

The filtering is an addition of:

• the original signal

• the original signal band-passed with centre

frequency = 1⁄4fs

• the original signal high-passed with maximum gain at

frequency = 1⁄2fs.

The band-passed and high-passed signals are weighted

with factors 0, 1⁄8, 1⁄4 and 1⁄2. The impulse response

becomes [−α, −β, 1 + 2α + 2β, −β, −α], where α is the

band-pass weighting factor and β the high-pass weighting

factor.

Coring is added to obtain no gain for low amplitudes in the

(high-pass + band-pass) signal, which is then considered

to be noise. Coring levels can be programmed as 0 (off),

+1/−2, +3/−4 and +7/−8 LSB at 10-bit word.

A limiter brings back the 11-bit range to a 9-bit range with

a clipping function on the lower and upper side.

12

handbook, halfpage

10

IH_PeakingI

(dB)

8

6

4

2

MGE097

(1)

(2)

(3)

(4)

0

0

(1) β = 1⁄2.

(2) β = 1⁄4.

(3) β = 1⁄8.

(4) β = 0.

1/4fs

1/2fs

Fig.7 Peaking transfer function with variation of β

(α = 1⁄8).

12

handbook, halfpage

10

IH_PeakingI

(dB)

8

6

MGE098

(1)

(2)

(3)

(4)

4

2

0

0

(1) β = 1⁄2.

(2) β = 1⁄4.

(3) β = 1⁄8.

(4) β = 0.

1/4fs

1/2fs

Fig.8 Peaking transfer function with variation of β

(α = 1⁄4).

1996 Oct 25

9

Share Link: