Tektronix WVR610A, Service Manual

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Theory of Operation
WVR610A & WVR611A Waveform Rasterizers Service Manual
3- 3
given frame, the intensity map is built up in one memory chip and read out of the
other. The functions are swapped on the next field.
Recursion and Picture Processing Engine
The output of the rasterizer feeds the picture and recursive processing engine in
the second large FPGA. This engine adds the previous frame to the present frame
to reduce flicker and improve brightness. It also converts the picture and
waveform signals from the input rate of 50 or 59.94 Hz to 60 Hz frame rate to
work with the XGA monitor. The picture and waveform data are combined with
the graphics and audio bar information from the control processor, then output to
the XGA DAC to drive the external monitor. Note that the parallel data from the
serial digital input, and the parallel stream from the composite decoder bypass
the waveform processing engine and connect directly to this FPGA to provide
the picture functionality.
Control Processor
The control processor is in charge of all the operational modes in the instrument,
and it draws the audio bars. The control processor communicates with the front
panel through RS232 signaling. It uses either parallel or the I2C bus for control
of most other the internal devices. A few parts communicate through other bus
types like JTAG or SPI. Audio data is input to the control processor via the 8 bit
HPI bus.
The control processor interfaces to the Ethernet through a dual rate switch. This
allows the network connection to run at 10 or 100 MB/s.
Front Panel
The front panel contains a small processor that communicates to the control
processor through RS232 signaling. Power, ground, fault and a programming
signal to allow the front panel processor flash code to be updated are also
included in the interface.
LTC and VITC Decoder
LTC and VITC signals are routed to the decoder chip. The control processor
reads the time values from the decoder chip. If selected by the user, the decoded
time values can be displayed on the XGA monitor and used to time stamp alarm
log entries.