Theory of Operation
The control processor interfaces to the Ethernet through a dual rate connection.
This allows the network connection to run at 10 or 100 MBps.
LTC
LTC inputs come from the remote connector. The LTC signal is applied to an A/D
converter and then input to the waveform processing FPGA, which decodes the
time code information.
NOTE.
The FPGAs decode VITC signals digitally.
Front Panel
The front panel contains a small processor which communicates with the control
processor through RS232 signaling. Reprogramming can be done through the SPI
if the front panel processor
fl
ash code must be updated.
Composite Input Option CPS
The Composite inputs are also passive loop-throughs. If unterminated, the signal
appears twice as large as it should. The inputs are either AC or DC coupled,
depending on the DC Restore setting. The selected input signal is
fi
ltered and
applied to an A-to-D converter to generate a 14-bit parallel signal, which is routed
to the DSP FPGA on the Main board, where it is demodulated in the digital
domain.
Audio Options AD and DPE
The audio option (if installed) resides on the upper "mezzanine" board. There are
two audio options available.
Option AD adds Analog Audio Monitoring (2 sets of 6 channel Analog Audio
inputs and 8 channels of Analog Audio outputs) and 16 channels Embedded
and AES/EBU Digital Audio support (8 channels at a time).
Option DPE adds Option AD capabilities plus support for decoding and
monitoring Dolby E and Dolby D Audio.
Audio Processing
Both audio versions have the same basic processing engine. This uses an FPGA to
route the audio input into two DSP chips, whose main function is to calculate the
peak values for the selected meter ballistics (response characteristics).
The audio data has two paths to the display. On one path, peak values are sent
to the control processor which then plots the bar and surround displays. On the
second path, raw data samples are sent to the waveform processing engine which
interpolates and plots it to generate the lissajous, or “phase,” display.
6
WVR7200 Waveform Rasterizer Service Manual
