Transmission - Encoders

After several frustrating weeks we now have three encoders up and running. Dan and I spent Saturday figuring out what was wrong and how to get a functional system. We began by connecting each encoder to the Thesys Controller one at a time via a cross-over cable, this let us boot them via TFTP and as such three began to work individually.

Installing a switch into the system meant that we could boot all three encoders without the need for us to constantly replug the cross-over cable. Once the encoders were running it was then a case of providing a system diagram for them to read from. This diagram also allows the user to adjust several other parameters such as bit-rates and IP addresses along with detailing any alarms in the system, it also means that the individual sources (video/audio) can be defined along with the type of output required from the encoders. Using an existing file that we knew worked from a previous year we began tailoring the individual parameters to the current system.

Once this was working we moved onto the Tandberg Multiplexer. In previous years this had been used as a re-multiplexer, with the initial multiplexing being done by the now defunct Divicom Mux. However this didn't present to much of a problem, all that we needed to do was identify the incoming Programme Association Tables (PAT) (which was done using the Transport Stream Analyser (TSA)) and re-assign the Packet Identifiers (PID) to what we required them to be. Other things done at this point was to ensure that the PCR was assigned so that it appeared with the video stream and define the services so that the channels had names and the video and audio were associated together.

Once all of this had been achieved it was merely a case of looping the Mux output through the TSA and then looping the stream again through three Integrated Receiving Devices (IRD), we used these to decode the pictures and audio so that we could see the channel outputs on monitors. All three encoders were used to code three separate channels because even though this isn't how it would be done in the event (the plan is to have a 1 to 'n' configuration in terms of redundancy) we wanted to make sure that all of them could work.

The next step is to rig up the equipment either side of the encoders, so the modulator and the presentation equipment (bug burners, WSS coders etc).