Grass Valley NV7512 v.1.3 - Manual (Page 34)

24 Rev 1.3 • 10 Oct 08
1. Introduction
Active Cards
Status Reporting
All input cards feature a circuit that performs status reporting and drives the card’s functions. Two
LEDs on the front of the input card indicate the card’s status: alarm (Red), power good (Green).
Three additional LEDs situated further back on the card indicate if software is loaded (Amber), if
there is good communication with the control card (Green) or bad communication with the control
card (Red). For more information, see
Indicator LEDs on page 100.
Crosspoint Cards
A crosspoint card (EM0525) receives signals from the input cards and commands from the control
card. The crosspoint card then performs switching as directed, sending signals to up to four output
cards. Each crosspoint card can receive up to 512 inputs and distribute up to 128 outputs.
The NV7512 crosspoint cards feature Time Domain Mulitplexing (TDM). TDM technology
enables multiple signals to travel on a single cable by placing the incoming signals in a continuous
stream. This enables signals to be sent between input cards and output cards, and between frames,
using a significantly fewer number of crosspoint connections. In turn, this reduces the amount of
physical space required to house the router frame. In addition, the crosspoint card is able to store
and switch AES synchronous channels separately for mono switching.
On the crosspoint card, memory is divided into four segments, one for inputs from the local input
cards and three for inputs from up to three additional connected frames. For example, one segment
of memory is used for Router 1, the current frame, the next segment is used for Router 2, the next
segment for Router 3, and so on.
Crosspoint Card Functions
Each crosspoint card receives inputs from the local router and from any connected routers (up to
four total). Local inputs are forwarded to a TDM mulitplexer and a TDM crosspoint circuit. The
TDM multiplexer creates three copies of the signal, forwarding each copy to the expansion connec-
tors. The TDM crosspoint circuit forwards signals to four output cards on the local router. Signals
received from the expansion connections are forwarded to a TDM demuxer, which in turns sends
the signals to the TDM crosspoint circuit. The TDM crosspoint circuit forwards a signal to four
output cards on the local router.