Sierra Video Sequoia Family - Manual (Page 33)

THEORY OF OPERATION
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Digital Video Signal Path Overview
The Sequoia Series digital video routers are based on a conventional "one stage" (for compact
routers up to 128X128 in size) or “two stage” (for expandable routers up to 512X512 in size)
crosspoint matrix design.
32 Input module
128 x 64 crosspoint/output module
4X1X32 Output module
Each input buffer assembly consists of a PCB which is installed and removed from the front of the
router frame. Rear panel BNC connectors pass through intermediate connectors to 32 IC's which
adaptively equalize incoming video signals, providing correct terminations to external sources and
providing 50 Ohm source impedance signals for crosspoint assemblies. One or two 50 Ohm
impedance coaxial ribbon cables connect the 32 outputs of each input buffer assembly to one or
two crosspoint or crosspoint/output assemblies.
128X64 crosspoint assemblies accept up to (4) 32 signal ribbon cables from input boards, or up
to 128 signals from a crosspoint backplane bus, which can be driven by a crosspoint board to
which input cables have been attached. One or two 32 signal coaxial ribbon cables leave each
crosspoint assembly and connect to output assemblies.
4X1X32 output assemblies consist of (32) 4X1 switchers, reclockers, and output buffers. 1 to (4)
32 signal coaxial ribbon cables arrive at each output board from up to (4) 128X64 crosspoint
assemblies. This allows each output to connect to 4X128 or 512 inputs in the three board system.
For a 128 x 128 compact system, there will be 4 input cards and 4 crosspoint/output cards. For a
256 x 256 frame there will be 8 input cards, 8 crosspoint cards, and 8 output cards. In a 512X512
router, there will be 16 input cards, 32 crosspoint cards, and 16 output cards.