Theory Of Operation - Hall Research Technologies HR-733 User Manual

4.0 Theory of Operation

The Sender provides both digital (HDMI/DVI), and analog (VGA/YPbPr
+ audio) inputs. However, in the fiber video is transmitted as digital
regardless of the selected input, and always comes out as HDMI on the
receiver with audio embedded in the video on the same connector. When
the analog input is selected, its video and audio are digitized and scaled to
match the native resolution of the remotely connected LCD.
The video data is transmitted on only one multi-mode fiber. The reason
multi-mode cable is needed is because the TMDS data are transmitted
over a range of optical wavelengths to reduce bandwidth requirement at
any particular wavelength. The TMDS signals use LED lasers to drive the
cable. However, for safety reasons, these lasers are not turned on if no
fiber optic cable is plugged in at both the Sender and Receiver.
Additional (non-video) DVI or HDMI signals are also seamlessly
connected between the source and the sink device. These include:

DDC Channel (SDAT and SCLK) for EDID and HDCP

Hot Plug Detect (to detect remote monitor connection)

Source Active +5vDDC (to indicate to sink there is a source)
In addition, the fiber-optic link provides a general purpose bi-directional
data lane that can be assigned by the user to be used as RS-232 pass-
through between sender and receiver, or to extend the CEC standard of the
HDMI. Currently CEC is seldom used in pro-AV installations, and its
implementation varies from one TV manufacturer to another, so as default
the HR-733 uses the data lane for RS-232 communication and control.
However, the CEC can be selected by the user, in which case the RS-232
port on the remote unit will not serve any function (the RS-232 port on the
Sender can still be used for source selection).
HDMI, VGA/YPbPr, and Serial over Single Fiber
Figure 2 - Connection Block Diagram
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