Orban OPTIMOD 8685, Руководство по эксплуатации, Страница: 269 / 357

OPTIMOD SURROUND PROCESSOR TECHNICAL DATA
6-13
HD-SDI Module (optional)
As stated above, we do not recommend attempting to service the HD-SDI circuit
board at the component level because it is a high-speed 10-layer board and easy to
damage. Nevertheless, for completeness, we provide a parts list, parts locator draw-
ings and schematics for the SDI module. The parts locator drawings and schematics
are located from page 6-79 to 6-100. In the schematics, many of the ICs are labeled
to describe their functionality.
The SDI receiver consists of a cable equalizer, U200, which extracts the SDI signal.
The cleaned-up signal is processed by an FPGA (see page 6-88), which extracts and
re-embeds the video signal, the audio signals, and the metadata within the VANC
area of the SDI. The metadata is further processed by a PIC microprocessor (U500),
which also provides the interface between metadata received and emitted from the
RS485 serial ports, the SDI VANC area, and Dolby-E (when the optional Dolby-E de-
coder and/or encoder modules are fitted; see page 6-93). In addition, the PIC delays
the metadata as necessary to match the delay applied to the video signal.
In addition to embedding and de-embedding the audio, the FPGA works in conjunc-
tion with the DSPs to implement the 8685’s routing switcher. For example, this al-
lows audio received from the SDI to be routed to the 8685’s audio processing or
AES3id outputs.
The FPGA also controls the video memory that permits the video signal to be de-
layed by up to 11 frames before being re-embedded into the SDI. The video memory
is shown on page 6-89.
Abbreviations
Some of the abbreviations used in this manual may not be familiar to all readers:
A/D (or A to D) analog-to-digital converter
AES Audio Engineering Society
AGC automatic gain control
A-I analog input
A-O analog output
BAL balanced (refers to an audio connection with two active conductors and one shield sur-
rounding them).
BBC British Broadcasting Corporation
BNC a type of RF connector
CALIB calibrate
CIT
composite isolation transformer
CMOS complementary metal-oxide semiconductor
COFDM Coded Orthogonal Frequency Division Multiplex—a robust type of digital modulation using
many narrow-bandwidth, low data rate, mutually non-interfering carriers to achieve an ag-
gregate high data rate with excellent multipath rejection.
COM serial data communications port
D/A (or D to A) digital-to-analog converter
dBm decibel power measurement. 0 dBm = 1mW applied to a specified load. In audio, the load
is usually 600
Ω
. In this case only, 0 dBm = 0.775V rms.