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T-Gate Enterprise Digital Televsion

T-Gate is a blade system. Each blade receives a digital TV broadcast, filters the required programmes and retransmits them to multiple targets on the local network. By using different receivers on the blade variants we have a terrestrial and a satellite version. With a suitable MPEG-2 encoder and RF tuner we can make baseband video and analogue TV versions.


Digital TV channels are broadcast from terrestrial or satellite transmitters as multiplexed MPEG-2 transport streams, formatted according to the DVB standard. Each T-Gate blade acts as a gateway between a DVB multiplex and an Ethernet network. In the case of DVB-S (satellite) and DVB-T (terrestrial), each blade is capable of transporting an entire DVB multiplex onto the Ethernet network. This represents a data rate of about 45Mbit/s and 24Mbit/s respectively.

The DVB multiplexes usually contain several TV and radio channels. The T-Gate blades can be configured to filter the channels into separate network streams to avoid flooding the network clients with data. Up to seven separate UDP streams can be configured. Each network stream would usually contain a TV channel or several radio channels.

T-Gate Network diagram

Up to 16 packet IDs can be selected from the incoming DVB multiplex for each UDP stream. These can include audio, video, subtitles, system information and data. The network streams will contain modified PAT and PMT packets that correctly describe the new transport stream content.

Each T-Gate blade is running Linux to provide a TCP/IP stack on a RISC based CPU. This provides a UDP command interface to the blade's features as well as Telnet, RS232 and HTTP interfaces.

T-Gate requires very little configuration, much like a TCP/IP print server or a simple broadband router. In many cases the device will be automatically tune to a DVB multiplex and start streaming a TV channel.

If T-Gate is being used as part of a sophisticated entertainment or monitoring environment, our off-the-shelf scheduling and stream capture software, running on external server hardware can be added. Programmatic control can then be achieved via the UDP command interface for all the T-Gate blades in the system.

T-Gate is designed to fit onto a slightly extended Eurocard size PCB. Power and RF are supplied to the rear of the board, with all remaining I/O connectors and LEDs on the front edge. Enclosure options include a 3U 19" rack mount chassis for up to 12 blades or small desktop cases for a single blade. The rack mount chassis supplies power and cooling to the blades and individual blades can be mixed and matched.

T-Gate is configured and controlled using a web browser based interface.

Specification

Networking
100Base-T full duplex Ethernet interface

RF front end information
Input/loop through: IEC UHF socket + plug
COFDM Modes: 2K and 8K supported
Frequency Bands: 146MHz to 862MHz
Modulation: QPSK, 16QAM, 64QAM
Guard Interval: 1/4, 1/8, 1/16, 1/32
Error Correction: Reed Solomon and Viterbi

Configuration
Interface provided by RS232, USB, Telnet, HTTP and Automation Interface

Dimensions
210x100mm (blade only)

Stream targets
Up to 11 unicast or multicast UDP streams. Each stream can filter up to 32 PIDs from the multiplex. This means that approximately 5 complete TV services from the original DVB transport stream can be streamed to a single UDP target. In most cases, a single TV service or up to 16 radio services are
streamed to each target. For specialised use, the complete DVB multiplex transport stream can be streamed to a target.

Management streams
Status and EPG information (where available) is optionally streamed to a separate UDP