Digital Signal Processor Explanation (Th-42Pz85U) - Panasonic TH-42PX80U Service Manual

Digital Signal Processor Explanation (TH-42PZ85U)

The main function of the A board is to select and process one of the incoming video signals. Video inputs 1 and 2,
Component Video Inputs 1 and 2, PC input, and the composite video output of the tuner are all are connected to
IC3001 for selection. The video output signal of the switch can be in any of the three formats: Video, Y/C, or Y, Pb, Pr.
The selected output enters IC4510, the HDMI IF Receiver/Decoder IC, for A/D conversion.
A comb filter inside IC4510 converts the composite video signal of the main picture to Y and C (luminance and
chrominance) signals. S-Video, which is already Y/C separated, simply passes through the comb filter. The
chrominance data is then applied to the Chroma Demodulator circuit to separate the color signal into Pb and Pr data.
At the completion of this process, the format of the composite or S-Video signal is now the same as a digital 480i
component signal. If the incoming video is in the 480p, 720P, or 1080i format, the Y, Pb, and Pr signals undergo A/D
(analog to digital) conversion only. The 10 bit YUV data is provided to a video switch.
The HDMI receiver section of IC4510 converts the incoming HDMI signals to a YUV video signal. The Video interface
circuit selects between the two HDMI sources and outputs the YUV signal to the switch. The output of the switch is
provided to another switch located inside the PEAKS LITE IC, IC8001.
Digital television reception of the tuner is output in the form of an IF (Intermediate Frequency) signal
IC8300 contains a detector circuit that retrieves the Transport stream from the IF signal. The transport stream then
enters the DTV I/F (Interface) section of IC8001 where the video signal is extracted and converted to YUV data. The
output is provided to the Video Input I/F for selection. The JPEG data of the SD card enters the JPEG I/F section of
IC8001 for conversion into YUV data and output to the Video Input I/F circuit. The video input interface outputs the
selected picture data to the video process circuit.
This Video Process section of the IC performs all picture control operations such as brightness, contrast, color, tint,
etc. On Screen Display data such as channel numbers, Digital TV closed caption, and picture adjustments are mixed
with the video data. The output signal is then applied to the LVDS (Low Voltage Differential Signaling) transmitter for
conversion into serial data. The LVDS transmitter transfers the video information from the A board to the D board. It
distributes signals with low-jitter, while creating little noise. It reduces power consumption and the generated noise
from data transmission. Another benefit of the LVDS standard is minimal concern for cable length.
The main MCU handles all video applications. It serves as the controller that monitors all operations of the TV section
(not display) of the unit.
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