MC1377P View Datasheet(PDF) - Motorola => Freescale

Part Name

Description

Manufacturer

MC1377P

COLOR TELEVISION RGB to PAL/NTSC ENCODER

Motorola => Freescale 

MC1377

I/Q System versus (R–Y)/(B–Y) System

The NTSC standard calls for unequal bandwidths for I and

Q (Figure 21). The MC1377 has no means of processing the

unequal bandwidths because the I and Q axes are not used

(Figure 22) and because the outputs of the (R–Y) and the

(B–Y) modulators are added before being output at Pin 13.

Therefore, any bandwidth reduction intended for the chroma

information must be performed on the composite chroma

information. This is generally not a problem, however, since

most monitors compromise the standard quite a bit.

Figure 23 shows the typical response of most monitors

and receivers. This figure shows that some crosstalk

between luma and chroma information is always present.

The acceptability of the situation is enhanced by the limited

ability of the CRT to display information above 2.5 MHz. If the

signal from the MC1377 is to be used primarily to drive

conventional non–comb filtered monitors or receivers, it

would be best to reduce the bandwidth at the MC1377 to that

of Figure 23 to lessen crosstalk.

Figure 20. NTSC Standard Spectral Content

Luminance

I

Q

0

1.0

2.0

3.0

4.0

f, FREQUENCY (MHz)

Figure 21. Color Vector Relationship

(Showing Standard Colors)

Red (R–Y)

(104°) (90°)

Purple

(61°)

I

(123°)

Yellow

(168°)

Color Burst

(180°)

Q (33°)

(B–Y) 0°

Blue

(348°)

Green

(241°)

Cyan

(284°)

Figure 22. Frequency Response of

Typical Monitor/TV

Gain

Luminance

Channel

Chroma

Channel

1.0

2.0

3.0 3.58 4.0

f, FREQUENCY (MHz)

MOTOROLA ANALOG IC DEVICE DATA

13

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