Rob.Analog

Horizontal Sync Depth Measurement in ADV7182/ADV728x

Discussion created by Rob.Analog on Sep 9, 2016

The following applies to the ADV7182, ADV7280, ADV7280-M, ADV7281, ADV7281-M, ADV7281-MA, ADV7282, ADV7282-M, ADV7283.

 

There is a register in these devices that can be used to measure the depth of the Horizontal Synchronization pulse of the incoming analog video. 

 

1) Connect analog video to DUT, Power up DUT and run an Analog Devices recommended script.

2) Ensure that the IN_LOCK and FSC_LOCK bits are high (User Map register 0x10 bits [2] and [0]). This will show that the DUT has locked to the analog video source.

2) Write 0x80 to register 0x0E.

3) Read the HSync depth by reading register 0x79.

    You can read this register as often as you like. However when you are finished reading the Hsync depth or if       you want to read/write to another register you must write 0x00 to register 0x0E.

 

4) When you read the Hsync depth convert the value to a decimal value.

      For a differential input multiply the decimal code by 2.004 to get the depth in mV on both the + and - inputs.

      For a single ended input multiply the decimal code by 3.159 to get the depth in mV of the single ended       input.

 

Notes

  • Note this gives an approximate value of the Hsync depth just before the resistor divider circuit on the input to the DUT.
  • Please ensure that the recommended resistor divider is used or else the calculations above will not work correctly (see datasheets for more information).
  • A single ended standard NTSC signal has a Hsync depth of 286 mV and standard PAL has a Hsync depth of 300 mV.

 

Regards,

Robert Hinchy

Senior Applications Engineer,

Analog Devices Inc.

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