PRODUCT SPECIFICATION
TMC22091/TMC22191
NTSC Subcarrier
PAL Subcarrier
For NTSC encoding, the subcarrier synthesizer frequency
has a simple relationship to the pixel clock period, repeating
over 2 lines: The decimal value is:
The PAL relationship is more complex, repeating only once
in 8 fields (the well-known 25 Hz offset):
(1135 ⁄ 4) + (1 ⁄ 625)
--------------------------------------------------
(pixels/line)
32
FREQ =
× 2
(455 ⁄ 2)
32
-----------------------------
(pixels/line)
FREQ =
× 2
This value must be converted to binary and split as described
previously for NTSC.
This value must be converted to binary and split into four
8-bit registers, FREQM, FREQ2, FREQ3, and FREQL. The
number of pixels/line is:
For PAL, the decimal value for SYSPH is found from:
FREQ
217
Pixels/line = (2/PXCK frequency) (H period)
SYSPH = --------------- = BURPH
SYSPH establishes the appropriate phase relationship
between the internal synthesizer and the chroma modulator.
The nominal value for SYSPH is zero.
This value must be converted to binary and split into two
8-bit registers, SYSPHM and SYSPHL. Burst Phase in PAL
is identical to SYSPH. Therefore, the same values for
SYSPHM and SYSPHL must be used for BURPHM and
BURPHL.
Other values for SYSPH must be converted to binary and
split into two 8-bit registers, SYSPHM and SYSPHL.
PAL-M Subcarrier
Burst Phase (BURPH) sets up the correct relative NTSC
modulation angle. The value for BURPH is:
(909 ⁄ 4)
32
-----------------------------
(pixels/line)
FREQ =
× 2
BURPH = SYSPH + 8,192
FREQ
SYSPH = --------------- = BURPH
217
This value must be converted to binary and split into two
8-bit registers, BURPHM and BURPHL. The decimal num-
ber 8,192 advances the burst phase by 45°.
Table 13. Standard Subcarrier Parameters
Subcarrier Register (hex)
Field
Rate
(Hz)
Horizontal
Freq.
(kHz)
Pixel
Rate
(MHz)
PXCK
Freq.
(MHz)
Sub-carrier
Freq.
(MHz)
BURPHM BURPHL SYSPHM SYSPHL FREQM FREQ2 FREQ3 FREQL
Standard
27
26
25
24
23
22
21
20
NTSC sqr.
pixel
59.94
59.94
59.94
50.00
50.00
50.00
60
15.734266
15.734266
15.734266
15.625000
15.625000
15.625000
15.750
12.27
13.50
14.32
14.75
13.50
15.00
12.50
13.50
14.30
24.54
27.00
28.64
29.50
27.00
30.00
25.01
27.00
28.60
3.57954500
3.57954500
3.57954500
4.43361875
4.43361875
4.43361875
3.57561149
3.57561149
3.57561149
20
00
00
00
4A
AA
AA
AB
NTSC
CCIR-601
20
20
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
43
40
4C
54
4B
49
43
40
E0
00
F3
13
AA
45
DF
10
F8
00
18
15
C6
00
3F
66
3E
00
19
96
A1
51
D7
F5
NTSC 4x
fSC
PAL sq.
pixel
PAL
CCIR-601
PAL 15
Mpps
PAL-M sq.
pixel
PAL-M
CCIR-601
60
15,750
PAL-M 4x
fSC
60
15,750
33
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