Sony Tektronix WFM 1125 Service Manual page 63

Theory of Operation
A15 Relay & Sync board
CHANNEL SELECTOR
SYNC SEPARATOR
A10 Input board
HK 102/HK 202
WFM 1125 Option 0A/0B/0C/0D Service Manual
This section describes the electrical operation of the WFM 1125 Digital
Television Waveform Monitor Option 0A/0B/0C/0D using the major circuit
blocks or modules.
After input through CH A or CH B, the 1.48 Gbps serial signal is input to K200
through A15 Relay & Sync board J240 or J230. After either one is selected, the
serial signal input to the HK-102/HK-202 serial parallel conversion module on
the A10 INPUT board through J210.
The EXT REF signal is input the U130 buffer amplifier through J220 or J250.
The buffered signal is input the U100 and the U200 through two different low
pass filters. Although the U100 and the U200 are the NS (National Semiconduc-
tor) LM1881 which is sync separator, the functions of V-sync and the odd-even
are not used in this instrument. The U100 generates the composite NTSC sync
and the U200 generates the composite HDTV sync. The composite sync signals
are input to A10 U200 through the W100.
The input 1.48 Gbps serial data is converted into the Y signal (10-bit wide data)
and the Pb/Pr multiplex signal (10-bit wide) at a data rate of 74.25 MHz. The
module also generates the 74.25 MHz clock and the FRAME and CRCE signals.
The FRAME signal indicates distinction between the HD (horizontal synchro-
nization) and VD (vertical synchronization) numbers. The CRCE signal
indicates occurrence of a CRC error.
This module has a CPU interface attached, which enables the operator to make
various settings. Using this interface, this device turns on/off the unsurely data
mask.
The 74.25 MHz clock, Y, Pb/Pr, and FRAME signals are input to the DEMUX
circuit. The CRCE signal is buffered, resulting in output from the CRCE
connector (BNC) through J290. (This output signal can be monitored on the
oscilloscope etc.) The CRCE signal is input to the A20 MAIN board through
W110 in order to indicate CRCE errors.
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