Noise And Calibration; Measurement Window; Noise Measurement - Analog Devices Advantiv ADV7604 Hardware Manual

10.11 Noise and Calibration

The ADV7604 provides hardware for a noise and a calibration measurement. The two
measurements share some hardware control (window). However, they are different in the way they
examine the input data. The measurements are executed during a time window. The window can be
positioned anywhere within a line of video and the length can be selected to be 16, 32, 64, or 128
LLC clock cycles.
Notes:
• Both measurements are performed on the channel A
• Both measurements work on a video line basis and are performed during the active video of.
• The tap-off point for both measurements is right after the gain multiplier. Clamping and
AGC/manual gain will affect the numbers reported back.

10.11.1 Measurement Window

The window for the noise and calibration measurement is set via MEAS_WS[11:0] and
MEAS_WL[1:0].
MEAS_WS[11:0] , Measurement Window Start, CP Map, Address 0x81, [3:0]; Address 0x82,
[7:0]
Function
MEAS_WS[11:0]
xxxxxxxxxxxx
000000000100
MEAS_WL[1:0] , Measurement Window Length, CP Map, Address 0x81, [7:6]
Function
MEAS_WL[1:0]
00
01
10
11

10.11.2 Noise Measurement

For the noise or peak data measurement, the data during the window is monitored for the maximum
and the minimum value. After the window is closed, the difference between the two is presented. If
programmed during a quiet time of the input video, the value presented can be related back to the
level of noise within the video signal. The noise level is presented as an unsigned number. Levels
greater than 255 are saturated to 255.
Rev. F August 2010
Description
Start value (in LLC clock cycles) of the measurement window. A value
of 0 positions the window at the falling edge of the incoming HSync.
Default value
Description
Window length is 128 LLC clock cycles
Window length is 64 LLC clock cycles
Window length is 32 LLC clock cycles
Window length is 16 LLC clock cycles
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ADV7604