[ADV7280A] Saturation register (SD_SAT_Cb[7:0] (Address 0xE3) and SD_SAT_Cr[7:0] (Address 0xE4))

Hi,

I have a question about saturation register (SD_SAT_Cb[7:0] (Address 0xE3) and SD_SAT_Cr[7:0] (Address 0xE4)) of ADV7280A.

The table 27 and table 28 on UG-1176.pdf shows as follows:
0x80 Gain on Cb channel = 0 dB
0x00 Gain on Cb channel = −42 dB
0xFF Gain on Cb channel = +6 dB

It doesn't seem that the decibel value(db) is proportional to the register value.
So we don't understand the relationship between them. When we set values except 0x80, 0x00 and 0xFF to the registers, then we don't know how much saturation effect can be seen.

Could you provide us the relationship between the decibel value(db) and the register value including median value?
It's also okey something like a graph which we can understand the relationship.

Thank you!
Best regards.
Tamu

Parents
  • Hi,

    Could you tell me the status about this question?

    Thank you!
    Best regards.
    Tamu

  • 0
    •  Analog Employees 
    on Dec 9, 2020 3:27 PM 2 months ago in reply to Tamu

    Hi Tamu San,

    When we set values except 0x80, 0x00 and 0xFF to the registers, then we don't know how much saturation effect can be seen ?

       "0xE3 and 0xE4" registers would effectively increase or decrease the gain according to the register value", so depending on that saturation effect will vary.

        Please note that As per expert comment  "Design confirmed that the chroma gain control does not apply to SECAM. It only applies to QAM standard like NTSC and PAL. The gain in the SECAM signal decoding is a function of the FM demodulator and is fixed. However customers can adjust the SECAM color levels by adjusting the Cb/Cr saturation controls (Reg 0xE3 and 0xE4). This would effectively allow them to increase or decrease the SECAM gain.

    Note:  Saturation is the amount of color present. For example, a lightly saturated red looks pink, while a fully saturated red looks like the color of a red crayon. Saturation does not mean the brightness of the color, just how much pigment is used to make the color. The less pigment, the less saturated the color is, effectively adding white to the pure color.

    Please refer  video-demy5 pdf for more information which related to saturation.

    Thanks,

    Poornima

  • 0
    •  Analog Employees 
    on Dec 10, 2020 6:01 PM 2 months ago in reply to Tamu

    Hi Tamu San,

           As i said already "These(0xE3,0XE4) registers would effectively increase or decrease the gain according to the register value", So customers only need to check the relationship between gain(db) against their register value.

          Please note that, we don't have any details other than what design support files manuals specifies.

    Thanks,

    Poornima

  • Hi Poornima san,

    Thank you for your reply.

    Of course, I think the customer should check the effect of the (0xE3,0XE4) registers on their board.
    But they want to know the more details as an index of their evaluation.

    I understand you don't have more details other than the documents.
    Even if you don't have all saturation values(dB) for all of the settings (from 0x00 to 0xFF),
    could you provide any useful information as an index for their evaluation?
    It's okey something like a graph, etc.
    Please refer attached file "SD_SAT_Cb_SD_SAT_Cr_index.xlsx".

    Or do you mean you don't have any useful information more than the manuals?

    Thank you!
    Best regards.
    Tamu

    XLSX

  • 0
    •  Analog Employees 
    on Dec 11, 2020 12:50 PM 2 months ago in reply to Tamu

    Hi,

     straight line from 0x00 to 0x80 is constant (linear).
     Gradient of the straight line from 0x80 to 0xFF is also constant (linear).

          Please let me know, Have you observed the same behavior in our evaluation board also ?

    Thanks,

    Poornima

  • Hi Poornima san,

    Thank you for your reply.

    So, do you mean the (0xE3,0XE4) registers indicate following specification?

    >Please let me know, Have you observed the same behavior in our evaluation board also ?
    => No. I have not observed the behavior in the evaluation board.

    Thank you!
    Best regards.
    Tamu

  • +1
    •  Analog Employees 
    on Dec 16, 2020 10:56 AM 2 months ago in reply to Tamu

    Hi Tamu-San,

    Do you mean the (0xE3,0XE4) registers indicate following specification?

             Yes, Saturation register values represent what you have intimated in the above graph. it seems saturation increases the gain is also increasing.

        Could you please crosscheck the same in our evaluation board?

    Thanks,

    Poornima

Reply
  • +1
    •  Analog Employees 
    on Dec 16, 2020 10:56 AM 2 months ago in reply to Tamu

    Hi Tamu-San,

    Do you mean the (0xE3,0XE4) registers indicate following specification?

             Yes, Saturation register values represent what you have intimated in the above graph. it seems saturation increases the gain is also increasing.

        Could you please crosscheck the same in our evaluation board?

    Thanks,

    Poornima

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