Digital Modulation Of Semiconductor Laser Large-screen TV

Semiconductor laser large-screen color TV (SLLTV) is a sort of new-style large-screen color TV. It has a wide foreground and a good developing potence. Digital modulation is a important part of SLLTV,and it must meet the demond of SLLTV. The accomplishment of digital modulation greatly improves the performance and function of SLLTV,and it greatly promotes SLLTV research.Color TV signal and its digitization are dissertated in this paper. In addition a profound research for the digitization parameters is made. Modular design is adopted in digital modulation system.In this way digital modulation system consist of vedio process module, synchronized drive module, semiconductor laser modulation and system control module. Vedio process module mainly accomplishes vedio decoding, AD conversion, interlace to progressive conversion, double frequency,etc. The chip of KS0122 is selected for vedio decoding and AD conversion with RGB digital vedio signal output. Interlace to progressive conversion is accomplished by means of "space for time".Double frequency designed may upgrade the sytem and meet the need of SLLTV research in future. Synchronized drive module produces horizontal drive signal in synchronization with horizontal synchronization signal and field drive sawtooth in synchronization with vertical synchronization signal.These signal drive scaning sytem of SLLTV. The clock control DA chip of MB40978 converts RGB digital vedio singal into amplitude-modulated RGB pulse that is magnified and inner-modulate laser. System control module accomplishes many functions ,such as systemic initialization, controling work of the system, man-machine interface and selecting channel.It communicates with other modules by I2C bus. Timing signals are inputed into microprocessor through P1 port and control signals are provided through P2 port. Count that judge key assignments and interrupt accomplish the function of keyboard.Two chip of SAA1064 with I2C interface compose 8 bit LED display subsystem.Thus the configuration are simplified.AT24c01 is selected for the data memory chip.I2C bus is the serial bus that is applied widely and is dissertated in the paper.Because the work frequency of the system is more high,anti-jamming measures is very important in PCB design. So many principles must be followed in the process of PCB design.