Chapter 2. Rackmounting and Hardware Overview

This chapter describes the VBOB hardware. The first section shows you how to mount the VBOB unit in a rack, and the following sections explain the theory of operation.

Mounting VBOB in an SGI 3000 Series Rack

You can install the VBOB chassis as a free-standing table-top unit, or mount it in a rack. This section explains how to install the VBOB chassis in an SGI 3000 series rack. Before you begin, make sure that you have the hardware listed in Table 2-1.


Warning: Personnel could be seriously injured and equipment could be damaged if the rack topples over. Install all equipment into the rack from the lowest available position. Also, make certain that the rack has sufficient power for the VBOB's needs. Check with the appropriate facilities authorities before installing this unit in a rack.



Note: This installation requires two people and a #2 Phillips screwdriver.

This procedure presumes that internal rackmounting rails are already installed and that a vertical space of 3.5 in. (8.9 cm) is available.

Table 2-1. Rack Installation Hardware for VBOB

Part Description

Quantity

10-32 x 1/4 in. screws

4

Front mounting brackets

1 pair


  1. Find the two front mounting brackets and the four 10-32 x 1/4 in. screws in the shipping container.

  2. Place the VBOB on a flat surface and attach the front mounting brackets, as shown in Figure 2-1.

  3. With one person holding each side, place the VBOB on the desired slide rails, then slide it inside the rack.

  4. Attach the VBOB to the rack, as shown in Figure 2-2, using appropriate screws for your rack.

    The VBOB chassis is now securely attached to the rack.

    Figure 2-1. Installing the Mounting Brackets on VBOB


    Figure 2-2. Installing VBOB in the Rack


Theory of Operation

VBOB is a digital video switcher that routes video inputs from different sources to various output formats. VBOB inputs include Serial Digital Standard Definition (SD) and High Definition (HD) BNC connectors, a Low Voltage Differential Signaling (LVDS) video input connector, and an optional dual-link Transition Minimized Differential Signaling ( TMDS) input. VBOB outputs include dual-link Serial Digital Standard Definition and High Definition BNC connectors, which you can use with applications where Alpha signals accompany the YUV video. In addition, VBOB includes an LVDS video output connector. Generator Locking Device (Genlock) input and loop-throughs for both Standard Definition Video and High Definition Video, and a RS-232 port for system upgrading and maintenance are also included.

Utilizing a highly advanced 80-bit parallel video crossbar, you can configure VBOB for various I/O applications. VBOB complies with the following standards:

  • High Definition SMPTE-292M

  • Standard Definition SMPTE-259M


    Note: HD and SD have separate connections, which allows you to switch between operational domains without switching cables.


LVDS Interface

LVDS is a new data interface standard that is defined in the TIA/EIA-644 and the IEEE 1596.3 standards. It transmits data at a high speed using a very low voltage swing (approximately 350mV) over two differential circuit board traces or a balanced cable. The LVDS drivers are current mode, so a termination resistor is required to complete the current loop and limit reflections due to the sub-nanosecond transition times over the transmission line.

Genlock

Genlock is a device that enables VBOB to receive an external sync signal, which locks the timing of the output video picture. This allows you to maintain a common timing across multiple video devices, which enables smooth dissolves, wipes, and other effects commonly used on broadcast TV. VBOB has two BNC connectors for Standard Definition genlock and two BNC connectors for High Definition genlock. You can use either of these connectors as an input or a loop-through.

TMDS Interface (optional)

TMDS is the basis of the Digital Visual Interface (DVI) standard, which transmits data using a differential interface with the data transitions minimized over a balanced cable.


Note: The TMDS Interface is optional. It is sometimes included as standard equipment when VBOB is purchased with TMDS-related products, such as HD GVO.

Figure 2-3. Internal Operation Block Diagram