Rev. 1.0, 02/00, page 746 of 1141
Noise Detection Operation: The noise detector considers an irregular pulse of the composite sync
signal (Csync) and a chip of a horizontal sync signal pulse within a frame as noise. The noise
counter takes counts of the irregular pulses during the high period of the noise detection window
and the chips and drop-outs of the horizontal sync signal pulses during the low period. The noise
detector counts more than one irregular pulses as one. The noise counter is cleared at every frame
(Vsync is detected twice).
The equalizing pulse contained in 9H of the vertical sync signal is counted also as an irregular
pulse.
The noise detection flag (NOIS) in the sync signal control register (SYNCR) is set to 1 if the count
of the irregular the count of the pulse chips and drop-outs of the horizontal sync signal >
4
×
(value of NDR7 to 0).
See the description on the sync signal control register (SYNCR) is section 26.15.5, Register
Description, for the NOIS bit.
Figure 26.76 shows the operation of the noise detection.
Csync
Noise detection
window
Noise detection
flag (NOIS)
Noise counter
Noise detection
level
Noise detection
flag is set.
NOIS : Bit 3 of the sync signal control register (SYNCR)
Noise
Figure 26.76 Operation of the Noise Detection