91¸£ÀûÉç

The 91¸£ÀûÉç makes use of seven to broadcast its channel and text service on satellite. Transponders are collections of channels, which are broadcast together in one bundle. 91¸£ÀûÉç One is scattered across transponders 1-6 due to its regional variations as bandwidth restrictions mean that we can't broadcast all of these on one transponder. 91¸£ÀûÉç Two Scotland is broadcast on transponder 2, whilst 91¸£ÀûÉç Three and 91¸£ÀûÉç Four are both on transponder 1 (see table below).

Alongside the channel broadcast, the 91¸£ÀûÉç also has some bandwidth allocated for the Red Button service on all of these transponders, and here is where it all gets more complicated.

The 91¸£ÀûÉç has two sets of bandwidth allocation for broadcasting 91¸£ÀûÉç Red Button text content, one equating to about 2Mbit/second and the other at about 6Mbit/second. The 2Mbit/second allocation ("Tier 1") accompanies all 91¸£ÀûÉç channels, whilst the 6Mbit/second allocation ("Tier 2") accompanies the 91¸£ÀûÉç's Red Button video such as the News Multiscreen and Children's content.

This means that viewers are able to look at the text service whilst watching a 91¸£ÀûÉç channel. However, the text service isn't the only thing that is broadcast using this allocation - the application that frames the text service and makes everything work also uses this.

We know that it's important for viewers to be able to check certain pieces of information like the news headlines quickly, and whilst watching 91¸£ÀûÉç programmes like Breakfast, so we've prioritised some of our content and included them alongside 91¸£ÀûÉç channels.

Unfortunately we can't include all of the text service in Tier 1, and we also have to balance the need to make this content available against the need to make the content available quickly. Otherwise, if all the Red Button text content was available alongside 91¸£ÀûÉç channels viewers would have to wait for a long time - a minute, for instance - to load the service to check the day's headlines.

Enter Tier 2. Here, as mentioned previously, we have up to 6Mbit/second of bandwidth for the text and application. Therefore, this is where we put all the content that we know is bandwidth-hungry like share prices, and you guessed it, Flight Arrivals.

When we decided to include Flight Arrivals in the Red Button service, there was a debate about where we should place this content for our service on satellite. Should we place it on Tier 1, thus giving viewers the ability to check this content whilst watching a 91¸£ÀûÉç channel? Against that, we knew that we would be adding over 140 extra pages to the service, and this would affect the service's loading time.

In the end, we opted to have Flight Arrivals added to Tier 2. This however presented us with another problem. Flight Arrivals content would be presented across the entire screen, but it would need to be categorised into regions and airports, and this must be displayed using existing menus - yet all our menus on Tier 2 require a quarter-screen video to be shown alongside them (see previous screenshot).

Due to the way the Red Button service is structured, our choices for the quarter-screen video accompaniment for Flight Arrivals are limited to the non-channel video content that we carry. In practical terms, this means choosing a piece of video content within the News Multiscreen service. In the end it was decided that it made the most sense to display the weather news video alongside Flight Arrivals; viewers could listen to weather audio whilst looking at Flight Arrivals information.

Farah Fahmy is a Development Producer working in the TV Platforms Group