This page introduces you to the appearance, purpose, key features and benefits of the Guardian™ 2800. It also familiarises you with the purpose and operation of the cards available in this system.

What is the Guardian™ 2800?
This is a multi-channel digital transmission system that integrates video traffic with data and/or audio traffic over one single mode fibre ring. You may transmit this data using Point-to-Point (PT-PT) or Drop, Add and Pass configurations. Real time digital transmission enables use of the Guardian™ 2800 in long distance applications with no signal degradation regardless of how many repeaters are incorporated to achieve the required transmission distance. It also provides support for an unlimited number of attached nodes.

The Guardian™ 2800 consists of a 19" 2U mainframe with twenty-four connector slots to hold plug-in cards. The plug-in cards receive, process and transmit video, data and audio traffic. The Guardian™ 2800's plug-in cards include video cards, optical cards, data cards and the microprocessor card.

Security and surveillance for road and rail transportation, industrial sites, town centres and campuses are common customer applications for the Guardian™ 2800 In these applications, the Guardian™ 28000 transmits camera-collected video information back to a control center.

Mainframe Overview
Click here for an overview of the Guardian™ 2800 mainframe

Microprocessor Card
The Microprocessor Card controls the configuration of the Guardian™ 2800 unit locally and communicates with other units in the network. The Microprocessor Card is already installed in your Guardian™ 2800, and has two ports on the back panel of the unit.

Port 1 - RS-232
A standard RS-232 9 pin interface for system control and monitoring.

Port 2 - Control
A high density 15 way D-type connector containing the following signals:
A secondary RS-232 control port Two alarm inputs
Two relay change over outputs External 5 volt power supply

The alarm inputs and relay change over outputs are monitored and controlled remotely through the Guardian™ 2800 control system.

Video Banks
Twenty of the Guardian™ 2800's connector slots are dedicated video input/output slots, which are configured into two banks labelled Video Bank A and Video Bank B. Each bank accommodates up to ten Video Input Cards or up to ten Video Output Cards, thus providing up to twenty input, twenty output or ten bi-directional video channels. You cannot mix Input and Output cards in the same bank. Each connector slot in Video Bank A and Video Bank B has a corresponding LED indicator on the unit’s front panel.

Video Input Cards
The Video Input Cards accept analogue video inputs in PAL or NTSC formats and linearly digitise the signals into a digitals bit stream with eight bit resolution. The video interface is via a standard 75 ohm BNC connector. When the card is seated in the Guardian™ 2800, this connector protrudes from the rear of the unit. Digitisation is synchronized to the incoming video line rate to avoid any jitter appearing on the ultimate video output. There are two different kinds of Video Input Cards: odd and even. The connectors on the odd Video Input Cards are in a low position, and plug into the odd numbered slots in the Video Banks (i.e., 1, 3, 5 etc). The connectors on the even Video Input Cards are in a high position, and plug into the even numbered slots in the Video Banks (i.e., 2, 4, 6 etc). The numbers for the slots are clearly labeled on the back panel of the mainframe, next to the connector holes. There is no functional difference between odd and even Video Input Cards.

Video Output Cards
The Video Output Card accepts the digital bit stream and converts the eight bit digital video signal back into its original PAL or NTSC analogue format.

There are two different kinds of Video Output Cards: odd and even. The connectors on the odd Video Output Cards are in a low position, and plug into the odd numbered slots in the Video Banks (i.e., 1, 3, 5 etc). The connectors on the even Video Output Cards are in a high position, and plug into the even numbered slots in the Video Banks (i.e., 2, 4, 6 etc). The numbers for the slots are clearly labeled on the back panel of the mainframe, next to the connector holes. There is no functional difference between odd and even Video Output Cards.

Optical Cards
The twenty serial video bit streams from Video Banks A and B connect to two High Speed Optical Card slots via a full cross-point switch. The Optical Card slots accept either a High Speed Optical Transmitter Card or a High Speed Optical Receiver Card.

High Speed Optical Cards
Each Guardian™ 2800 unit contains two High Speed Optical Cards. The High Speed Optical Receiver (Hi-Speed OpRx) Card accepts ten serial video bit streams and time division multiplexes them onto the fibre. The High Speed Optical Transmitter (Hi-Speed OpTx) Card does the inverse. Both optical cards operate on a 1310nm or 1550 nm wavelength range. You can combine these two wavelengths on a single fibre. The Hi-Speed OpTx operates at either 1310 or 1550 nm, and the Hi-Speed OpRx operates at both wavelengths.

Each optical card is primarily associated with one of the Video Banks. If Video Bank A contains Video Input cards, then Optical Card slot A contains a Hi-Speed OpTx. If Video Bank A contains Video Output cards, then Optical Card slot A contains a Hi-Speed OpRx. The same association exists between Optical Card slot B and Video Bank B.

The High Speed Optical Cards can carry audio and/or data signals, as well as video signals. These auxiliary signals do not displace the video signals.

Low Speed Opto Cards
There are also two Low Speed Opto Card variants: Low Speed Opto Transmitter (Lo-Speed OpTx) Card and Low Speed Opto Receiver (Lo-Speed OpRx) Card. These daughter board interface modules connect to the Data Card. Low-Speed Opto Cards carry the data/audio interfaces but do not have the bandwidth to carry video signals. Since the High Speed Optical Cards can carry all the signal formats, you may not require the Low Speed Opto Cards in your unit.

If, however, the network is carrying video signals in one direction only, a Lo-Speed Opto Card can carry data/audio signals in the reverse direction. Alternatively, a network can use the Low Speed Opto Cards to carry data/audio interfaces only, to provide overall network integrity, to act as back up channels or for network redundancy.

Combining Two Optical Card Channels
To reduce the number of optical fibres required, an Opto Coupler combines the fibres from two Optical Cards into one fibre.

An Opto Coupler requires that the two cards use two separate wavelengths (i.e., 1310 nm and 1550 nm).

The same Opto Coupler is used to combine or split the two wavelengths and is used with different combinations of High Speed and Low Speed Optical Cards. Depending on your configuration, you can install the coupler inside the Guardian™ 2800 unit itself or in between units.

Data and Audio Interfaces
The Guardian™ 2800 also contains two card slots for transmission of audio and data signals via the Data Cards A and B.

Each Data Card has five bi-directional data/audio channels that accommodate five bi-directional Data Interface Daughter Boards, providing a total capability of 10 bi-directional auxiliary interfaces. The specific Data Interface Daughter Boards offer a wide variety of standard audio and data interfaces, and complete flexibility on the overall configuration for the Data Cards. The Data Interface Daughter Boards fitted to the Data Cards define the data interface.

Data Card and Data Interface Daughter Boards
The following data interfaces are available for the Data Card:

	RS-232 Interface Daughter Board
	RS-422 – RS-485 Tx/Rx Daughter Board
	TTL Rx/Tx Interface Daughter Board
	20mA Current Loop Daughter Board
	Contact Closure Daughter Board
	Audio Card – 4 Wire Daughter Board

You set the desired data interface by plugging the Data Interface Daughter Board into the appropriate connector on the Data Card. The Data Interface Daughter Boards provide the appropriate external physical layer signal levels for data interfaces.

Audio Interfaces
The Data Cards also provide a line level audio interface. For audio signals, there is a 16 bit analogue to digital converter and digital to analogue converter. The audio bandwidth is 20 Hz to 17.5 kHz. The audio interface has a differential 600 ohm input and 600 ohm output impedance.

You set the desired audio interface by plugging the Data Interface Daughter Board into the appropriate connector on the Data Card. Two audio interfaces can combine to transmit and receive a single stereo audio signal pair.