7500 Series Instruction Manual
4-1
Section
4
Functional Description
Matrix Controller
The Matrix Controller (MC) modules are used in 7500 Series models. MCs
are designed to work in pairs (one primary, one backup) to provide failure
resistance. The primary MC provides all required functions; the backup is
ready to take over should the primary unit fail. Control logic facilitates
orderly change of control between the two modules and ensures that only
one module at a time controls the external serial busses.
Control consists of messages created to set matrix crosspoints, and the
return from the MC contains true tally status back to the control system.
The MC module can be inserted into a powered frame. To ensure that the
system power supply is not disturbed, a pre-charge resistor is connected in
series with one of the rear connector pins. The corresponding pin on the
backplane connector is longer than any of the other power pins. This allows
the pre-charge pin to make connection before the others.
A 25-pin D connector labeled
OPTION
is connected to the MC for use as an
optional interface.
A SMPTE Vertical Interval Time Code (VITC) reader is used to allow pre-
loaded events to be triggered on a particular SMPTE frame number. This
signal must be applied to the single coax vertical reference input.
Vertical interval reference is still required for crosspoint switching tasks.
This is an analog video input which can be NTSC or PAL. This input is pro-
cessed to extract vertical sync and odd/even field (if any) information. Pre-
defined progammable logic device (PLD) logic is used to create a switching
strobe that is offset into line 10 for NTSC or line 6 for PAL. A video presence
detector interrupts the processor if the video reference is missing. If this ref-
erence is missing then a fake sync is generated at a default asynchronous
interval.
Содержание 7500NB
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