AnsweredAssumed Answered

ADV7188 sin(x)/x response

Question asked by GuenterL Employee on Sep 14, 2012
Latest reply on Sep 24, 2012 by lberitau

I'm moving a private thread to forum

 

The schematic was keep private.  Scope capture provided

 

Excerpts from the email chain follow

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I implemented the ADV7188 and I did some measurement. The sinus(x)/x response have an overshoot around 400KHz and I don't understand why:

 

1) Can you explain me this behavior ?

2) Do you know a mean to inprove/modify the sinus(x)/x response ?

 

Here under is our chip default configuration:

 

00  INPUT CONTROL               RW  (00 hex)
01  VIDEO SELECTION             RW  (C8 hex)
02  VIDEO SELECTION 2           RW  (04 hex)
03  OUTPUT CONTROL              RW  (00 hex)
04  EXTENDED OUTPUT CONTROL     RW  (F7 hex)
05  PRIMARY MODE                RW  (00 hex)
06  VIDEO STANDARD              RW  (02 hex)
07  AUTODETECT ENABLE           RW  (01 hex)
08  CONTRAST                    RW  (80 hex)
0A  BRIGHTNESS                  RW  (00 hex)
0B  HUE                         RW  (00 hex)
0C  DEFAULT VALUE Y             RW  (36 hex)
0D  DEFAULT VALUE C             RW  (7C hex)
0E  ADI CONTROL                 RW  (00 hex)
0F  POWER MANAGEMENT            RW  (00 hex)
13  ANALOGUE CONTROL INTERNAL   WO  (04 hex)
14  ANALOGUE CLAMP CONTROL      RW  (12 hex)
15  DIGITAL CLAMP CONTROL 1     RW  (00 hex)
16  DIGITAL CLAMP CONTROL 2     RW  (00 hex)
17  SHAPING FILTER CONTROL      RW  (01 hex)
18  SHAPING FILTER CONTROL 2    RW  (93 hex)
19  COMB FILTER CONTROL         RW  (F1 hex)
1A  SCALING/CROPPING MSB        RW  (00 hex)
1B  ACTIVE VIDEO DESIRED LINES  RW  (00 hex)
1C  ACTIVE VIDEO VERTICAL BEGIN RW  (00 hex)
1D  VERTICAL SCALE VALUE 1      RW  (47 hex)
1E  VERTICAL SCALE VALUE 2      RW  (00 hex)

1F  ACTIVE VIDEO HORIZONTAL BEGIN   RW  (00 hex)

20  ACTIVE VIDEO DESIRED PIXEL  RW  (1D hex)
21  HORIZONTAL SCALE VALUE 1    RW  (1B hex)
22  HORIZONTAL SCALE VALUE 2    RW  (01 hex)
23  COLOUR SUBCARRIER CONTROL 1 RW  (C1 hex)
24  COLOUR SUBCARRIER CONTROL 2 RW  (3D hex)
25  COLOUR SUBCARRIER CONTROL 3 RW  (05 hex)
26  COLOUR SUBCARRIER CONTROL 4 RW  (05 hex)
27  PIXEL DELAY CONTROL         RW  (58 hex)
28  MANUAL CLOCK CONTROL 1      RW  (16 hex)
29  MANUAL CLOCK CONTROL 2      RW  (00 hex)
2A  MANUAL CLOCK CONTROL 3      RW  (40 hex)
2B  MISC GAIN CONTROL           RW  (E1 hex)
2C  AGC MODE CONTROL            RW  (AE hex)
2D  CHROMA GAIN CONTROL 1       WO  (B7 hex)
2E  CHROMA GAIN CONTROL 2       WO  (00 hex)
2F  LUMA GAIN CONTROL 1         WO  (FF hex)
30  LUMA GAIN CONTROL 2         WO  (FF hex)
31  VSYNC FIELD CONTROL 1       RW  (02 hex)
32  VSYNC FIELD CONTROL 2       RW  (41 hex)
33  VSYNC FIELD CONTROL 3       RW  (84 hex)
34  HSYNC POSITION CONTROL 1    RW  (00 hex)
35  HSYNC POSITION CONTROL 2    RW  (02 hex)
36  HSYNC POSITION CONTROL 3    RW  (00 hex)
37  POLARITY                    RW  (01 hex)
38  NTSC COMB CONTROL           RW  (80 hex)
39  PAL COMB CONTROL            RW  (C0 hex)
3A  ADC CONTROL                 RW  (17 hex)
3B  BIAS CONTROL                RW  (81 hex)
3C  TLLC CONTROL ANALOGUE       RW  (58 hex)
3D  MANUAL WINDOW CONTROL       RW  (A2 hex)
3E  BLANK LEVEL WINDOW          RW  (6A hex)
3F  BURST WINDOW                RW  (A0 hex)
40  SYNC TIP WINDOW             RW  (90 hex)
41  RESAMPLE CONTROL            RW  (01 hex)
42  LUMA COMB CONTROL           RW  (7E hex)
43  CHROMA COMB CONTROL         RW  (A4 hex)
44  VERTICAL DELAY CONTROL      RW  (FF hex)
45  COMB MIX CONTROL            RW  (B6 hex)
46  COMB HYS CONTROL            RW  (12 hex)
48  GEMSTAR CTRL 1              RW  (00 hex)
49  GEMSTAR CTRL 2              RW  (00 hex)
4A  GEMSTAR CTRL 3              RW  (00 hex)
4B  GEMSTAR CTRL 4              RW  (00 hex)
4C  GEMSTAR CTRL 5              RW  (70 hex)
4D  CTI DNR CTRL 1              RW  (AC hex)
4E  CTI DNR CTRL 2              RW  (08 hex)
4F  CTI DNR CTRL 3              RW  (08 hex)
50  CTI DNR CTRL 4              RW  (08 hex)
51  LOCK COUNT                  RW  (24 hex)
52  CSC_1                       RW  (80 hex)
53  CSC_2                       RW  (00 hex)
54  CSC_3                       RW  (00 hex)
55  CSC_4                       RW  (00 hex)
56  CSC_5                       RW  (00 hex)
57  CSC_6                       RW  (08 hex)
58  CSC_7                       RW  (00 hex)
59  CSC_8                       RW  (00 hex)
5A  CSC_9                       RW  (00 hex)
5B  CSC_10                      RW  (00 hex)
5C  CSC_11                      RW  (01 hex)
5D  CSC_12                      RW  (00 hex)
5E  CSC_13                      RW  (00 hex)
5F  CSC_14                      RW  (00 hex)
60  CSC_15                      RW  (00 hex)
61  CSC_16                      RW  (00 hex)
62  CSC_17                      RW  (20 hex)
63  CSC_18                      RW  (00 hex)
64  CSC_19                      RW  (00 hex)
65  CSC_20                      RW  (00 hex)
66  CSC_21                      RW  (00 hex)
67  CSC_22                      RW  (03 hex)
68  CSC_23                      RW  (01 hex)
69  CONFIG 1                    RW  (00 hex)
6A  TLLC PHASE ADJUST           RW  (40 hex)
6B  CP OUTPUT SELECTION         RW  (C0 hex)
6C  CP CLAMP 1                  RW  (00 hex)
6D  CP CLAMP 2                  RW  (00 hex)
6E  CP CLAMP 3                  RW  (00 hex)
6F  CP CLAMP 4                  RW  (00 hex)
70  CP CLAMP 5                  RW  (00 hex)
71  CP AGC 1                    RW  (40 hex)
72  CP AGC 2                    RW  (00 hex)
73  CP AGC 3                    RW  (10 hex)
74  CP AGC 4                    RW  (04 hex)
75  CP AGC 5                    RW  (01 hex)
76  CP AGC 6                    RW  (00 hex)
77  CP OFFSET 1                 RW  (3F hex)
78  CP OFFSET 2                 RW  (FF hex)
79  CP OFFSET 3                 RW  (FF hex)
7A  CP OFFSET 4                 RW  (FF hex)
7B  CP AV CONTROL               RW  (1E hex)
7C  CP HVF CONTROL 1            RW  (C0 hex)
7D  CP HVF CONTROL 2            RW  (00 hex)
7E  CP HVF CONTROL 3            RW  (00 hex)
7F  CP HVF CONTROL 4            RW  (00 hex)
80  CP HVF CONTROL 5            RW  (00 hex)
81  CP MEASURE CONTROL 1        RW  (F0 hex)
82  CP MEASURE CONTROL 2        RW  (04 hex)
83  CP MEASURE CONTROL 3        RW  (00 hex)
84  CP MEASURE CONTROL 4        RW  (0C hex)
85  CP DETECTION CONTROL 1      RW  (42 hex)
86  CP MISC CONTROL 1           RW  (0B hex)
87  CP TLLC CONTROL 1           RW  (63 hex)
88  CP TLLC CONTROL 2           RW  (5A hex)
89  CP TLLC CONTROL 3           RW  (08 hex)
8A  CP TLLC CONTROL 4           RW  (10 hex)
8B  DPP_CP_58                   RW  (04 hex)
8C  DPP_CP_59                   RW  (40 hex)
8D  DPP_CP_60                   RW  (22 hex)
8E  DPP_CP_61                   RW  (75 hex)
8F  FREE RUN LINE LENGTH 1      WO  (00 hex)
90  FREE RUN LINE LENGH 2       WO  (00 hex)
91  DPP_CP_64                   WO  (5F hex)
92  DPP_CP_65                   WO  (FF hex)
93  DPP_CP_66                   WO  (FF hex)
94  DPP_CP_67                   WO  (FF hex)
95  DPP_CP_68                   WO  (FF hex)
96  DPP_CP_69                   WO  (E0 hex)
97  DPP_CP_70                   WO  (FF hex)
98  DPP_CP_71                   WO  (FF hex)
99  DPP_CP_72                   WO  (FF hex)
9A  DPP_CP_73                   WO  (FF hex)
9B  DPP_CP_74                   WO  (FF hex)
9C  DPP_CP_75                   WO  (FF hex)
9D  DPP_CP_76                   WO  (FF hex)
9E  DPP_CP_77                   RW  (A4 hex)
9F  DPP_CP_78                   RW  (6D hex)
A0  DPP_CP_79                   WO  (FF hex)
A1  DPP_CP_80                   WO  (FF hex)
A2  DPP_CP_81                   WO  (FF hex)
A3  DPP_CP_82                   WO  (FF hex)
A4  DPP_CP_83                   WO  (FF hex)
A5  DPP_CP_84                   WO  (FF hex)
A6  DPP_CP_85                   WO  (FF hex)
A7  DPP_CP_86                   WO  (FF hex)
A8  DPP_CP_87                   WO  (FF hex)
A9  DPP_CP_88                   WO  (FF hex)
AA  DPP_CP_89                   WO  (FF hex)
AB  DPP_CP_90                   WO  (FF hex)
AC  DPP_CP_91                   WO  (FF hex)
AD  DPP_CP_92                   WO  (FF hex)
AE  DPP_CP_93                   WO  (60 hex)
AF  DPP_CP_94                   WO  (C0 hex)
B0  DPP_CP_95                   WO  (00 hex)
B1  DPP_CP_96                   WO  (6F hex)
B2  DPP_CP_97                   WO  (1C hex)
B3  DPP_CP_98                   WO  (71 hex)
B4  DPP_CP_99                   WO  (00 hex)
B5  DPP_CP_100                  WO  (00 hex)
B6  DPP_CP_101                  WO  (00 hex)
B7  DPP_CP_102                  WO  (13 hex)
B8  DPP_CP_103                  WO  (03 hex)
B9  DPP_CP_104                  WO  (33 hex)
BF  CP DEF COL 1                RW  (02 hex)
C0  CP DEF COL 2                RW  (00 hex)
C1  CP DEF COL 3                RW  (00 hex)
C2  CP DEF COL 4                RW  (50 hex)
C3  ADC SWITCH 1                RW  (00 hex)
C4  ADC SWITCH 2                RW  (00 hex)
C5  CP CLAMP POS HS CTRL 1      RW  (81 hex)
C6  CP CLAMP POS HS CTRL 2      RW  (00 hex)
C7  CP CLAMP POS HS CTRL 3      RW  (00 hex)
C8  CP CLAMP POS HS CTRL 4      RW  (00 hex)
C9  DPP_CP_118                  RW  (04 hex)
CC  CLAMP POSITION CONTROL      RW  (5B hex)
CD  FAST CLAMP CONTROL          RW  (00 hex)
CE  FINE CLAMP CONTROL          RW  (01 hex)
CF  PEAK WHITE CONTROL 1        RW  (B4 hex)
D0  PEAK WHITE CONTROL 2        RW  (00 hex)
D1  PEAK WHITE CONTROL 3        RW  (10 hex)
D2  PEAK WHITE CONTROL 4        RW  (FF hex)
D3  PEAK WHITE CONTROL 5        RW  (FF hex)
D4  PEAK WHITE CONTROL 6        RW  (7F hex)
D5  PEAK WHITE CONTROL 7        RW  (7F hex)
D6  PEAK WHITE CONTROL 8        RW  (3E hex)
D7  PEAK WHITE CONTROL 9        RW  (08 hex)
D8  PEAK WHITE CONTROL 10       RW  (3C hex)
D9  PEAK WHITE CONTROL 11       RW  (08 hex)
DA  PEAK WHITE CONTROL 12       RW  (3C hex)
DB  PEAK WHITE CONTROL 13       RW  (9B hex)
DC  LETTERBOX CONTROL 1         RW  (AC hex)
DD  LETTERBOX CONTROL 2         RW  (4C hex)
DE  SECAM DR ADJUST             WO  (00 hex)
DF  SECAM DB ADJUST             WO  (00 hex)
E0  SD SYNC TIME CONSTANT       RW  (14 hex)
E1  SD OFFSET U                 RW  (80 hex)
E2  SD OFFSET V                 RW  (80 hex)
E3  SD SATURATION U             RW  (80 hex)
E4  SD SATURATION V             RW  (80 hex)
E5  NTSC V BIT BEGIN            RW  (25 hex)
E6  NTSC V BIT END              RW  (04 hex)
E7  NTSC F BIT TOGGLE           RW  (63 hex)
E8  PAL V BIT BEGIN             RW  (65 hex)
E9  PAL V BIT END               RW  (14 hex)
EA  PAL F BIT TOGGLE            RW  (63 hex)
EB  VBLANK CONTROL 1            RW  (55 hex)
EC  VBLANK CONTROL 2            RW  (55 hex)
ED  FB_CONTROL1                 WO  (12 hex)
EE  FB_CONTROL 2                RW  (00 hex)
EF  FB_CONTROL 3                RW  (4A hex)
F0  FB_CONTROL 4                RW  (44 hex)
F1  FB_CONTROL 5                RW  (0C hex)
F2  FB_CONTROL 6                RW  (32 hex)
F3  AFE_CONTROL 1               RW  (01 hex)
F4  DRIVE STRENGTH              RW  (15 hex)
F5  PEAK WHITE CONTROL 14       RW  (E0 hex)
F6  PEAK WHITE CONTROL 15       RW  (69 hex)
F7  PEAK WHITE CONTROL 16       RW  (10 hex)
F8  IF COMP CONTROL             RW  (00 hex)
F9  VS MODE CONTROL             RW  (03 hex)
FA  ADC PERFORMANCE             RW  (A0 hex)
FB  PEAKING CONTROL             RW  (4F hex)
FC  CORING THRESHOLD 2          RW  (04 hex)

 

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1) To test the chip, I use a professionnal CVBS generator and a PAL analyzer: I can insert test pattern (CCIR17, CCIR18, CCIR330, CCIR331 2T pulse, sin(x)/x) in different lines.

 

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I send you :

  1. Our schematic  of the ADV7188. I tested the prototype and the component works well. I change some default register values to obtain the maximum signal (CVBS) quality because it will be modulated in VHF/UHF in PAL standard (from BT656 bus).
  2. The Sinus(x)/x response of the component. For this I use professional equipment (PLISCH) to generate a CVBS sinus(x)/x and another equipment to measure the response from the modulated signal in UHF.
  3. The ADV7188 configuration: I try a lot of configuration to obtain the best signal quality to meet our requirements (Level diagram, 2T pulse, Luma/Chroma distortion, SNR, Intermod, Multi-burst reponse…) .

 

Globally, all measurements are OK but I try to find the reason of the 400KHz disturbance in the sinus(x)/x response. There is no spurious at this frequency in the video spectrum, so I think it is a behavior of the digital process of the ADV7188. Do you know how I can improve this parameter?

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