NEC PlasmaSync 50MP1 User Manual page 104

(4) SECAM decoding
When a color signal of SECAM is received, IC5510 (SECAM decoding) receives the control signal from Pin
3 of IC5504 (PAL/NTSC).
Inside the IC5510 (SECAM decoding), the chroma signal input of Pin 24 is processed for band limitation at
the bell filter and is then amplified at the limiter circuit. Since then, FM decoding and de-emphasis are
carried out. After the signal has been switched with the foregoing control signal, the chrominance output is
generated from Pin 10 and Pin 11.
When this signal input is entered in Pins 26/27 of IC5508 (1H DELAY), operation of interpolation is con-
ducted at the intervals of one hour (1H) and the output is generated from Pins 29/30. This output is entered
in Pins 7 and 8 of IC5503 (CTI).
In IC5503, profile compensation for the color signals is effected. When the output is generated from Pins 11
and 12, it is then returned to Pins 51 and 52 of IC5504.
(5) 1H DELAY
Information about the color system of received signals is entered from Pin 7 of IC5504 to Pin 24 and Pin 25
of IC5508. According to this information, presence of operation in the internal circuits is examined and AMP
gain changeover is carried out.
System
NTSC
PAL
SECAM
Voltages at Pin 24 and Pin 25 of IC5508
0V
8.3V
4.6V
6