Stanford Research Systems
4
Distribution Amplifiers
SDI distribution amplifier
SDI (serial digital interface) is a physical interface used to transmit uncompressed component
digital video in a variety of formats. There are several standards defined by the Society of
Motion Picture and Television Engineers (SMPTE) which transmit 800 mV
pp
logic over 75
Ω
coax at rates up to 2.97Gb/s.
Cable attenuation and dispersion degrade SDI signals. Two techniques are used to restore
signals: equalization and reclocking. Equalization circuits modify the frequency response of
the input amplifier to compensate for the cable losses at high frequencies. Reclocking circuits
recover the data clock (by phase locking a local oscillator to transitions in the data stream)
and resynchronize the output data to this recovered clock.
Important characteristics of an SDI distribution amplifier include input cable equalization,
agile clock recovery and resynchronization, good matching of the 75
Ω
cable impedance to
both inputs and outputs, fast output transition times, small overshoot, and compliance with
common data rates (270, 1483.5, 1485, 2967 and 2970 Mb/s).
More in development
Other distribution amplifiers, which are compatible with the FS730 & FS735 systems, are
currently in development. Check the SRS web site,
www.thinkSRS.com
, for current
information.
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