Texas Instruments TVP5147M1PFP manual 2.2.2.2 Y/C Separation, 5. Color Low-Pass Filter With Filter

Functional Description

	10
	0
	−10
− dB	−20
Amplitude	−30
	−40	ITU-R BT.601 −3 dB
		@ 1.42 MHz
	−50
	−60
	−70
	0.0	0.5	1.0	1.5	2.0	2.5	3.0	3.5	4.0
				f − Frequency − MHz

Figure 2−4. Color Low-Pass Filter Frequency

Response

2.2.2.2Y/C Separation

	10				Filter 2
	0				−3 dB @ 844 kHz
							Filter 0
	−10					−3 dB @ 1.41 MHz
							Filter 3
− dB	−20					−3 dB @ 554 kHz
							Filter 1
Amplitude	−30
							−3 dB
							@ 1.03 MHz
	−40
	−50
	−60
	−70								4.0
	0.0	0.5	1.0	1.5	2.0	2.5	3.0	3.5
				f − Frequency − MHz

Figure 2−5. Color Low-Pass Filter With Filter

Characteristics, NTSC/PAL ITU-R BT.601

Sampling

Y/C separation can be done using adaptive 5-line (5-H delay) comb filters or a chroma trap filter. The comb filter can be selectively bypassed in the luma or chroma path. If the comb filter is bypassed in the luma path, then chroma trap filters are used which are shown in Figure 2−6 and Figure 2−7. The TI patented adaptive comb filter algorithm reduces artifacts such as hanging dots at color boundaries. It detects and properly handles false colors in high-frequency luminance images such as a multiburst pattern or circle pattern.

Amplitude − dB

10		10
5	Notch 3 Filter	5	Notch 3 Filter

0 0

−5

−5

−10

Notch 2 Filter

− dB

−10

Notch 2 Filter

−20

Amplitude

−20

−15

Notch 1 Filter

−15

Notch 1 Filter

−25

−25

−30

No Notch Filter

−30

No Notch Filter

−35

−35

−40

−40

0

1

2

3

4

5

6

7

0

1

2

3

4

5

6

7

f − Frequency − MHz

f − Frequency − MHz

Figure 2−6. Chroma Trap Filter Frequency

Figure 2−7. Chroma Trap Filter Frequency

Response, NTSC ITU-R BT.601 Sampling

Response, PAL ITU-R BT.601 Sampling

SLES140A—March 2007 TVP5147M1PFP 13