Techie Stuff - Broadcast Encoder

Written on 11/05/2016
Toby Mills

The very first step in building a TV channel is figuring out how you are going to get the signal to everyone and then buying (or in our case building) the equipment to do it.

We will be broadcasting using Freeview which means we have to get our signal from Masterton up to the broadcast towers on Popoiti Hill 23km away. This is quite a logistical challenge.

All the parts for our Broadcast Encoder

The first thing we have to do is convert our High Definition studio signal which uses 3 Gigabits of data per second into something that can be efficiently transmitted the 23km up to the broadcast towers, ingested into the Freeview network and then broadcast over the airwaves in all directions by the Tower. We also need to make sure the signal is in a very special format so that all your TV's and set top Freeview boxes can recognise and decode the signal.

To do this, we use a piece of equipment called a broadcast encoder. These things normally cost upwards of $20,000 each and they reduce the 3 Gigabit per second signal down to a tiny 2.5 Megabits per second.

Luckily our highly technical backroom geeks have the skills to actually build one of these contraptions from scratch so here you can see all the parts in ominous looking cardboard boxes waiting to be assembled..

Our Broadcast Encoder

After several days of assembly and compiling code its all together in one piece and ready for testing. We are using an open source encoder based on Linux using code made public by the BBC.

In the next installment we will begin work on the long range link that will get us up to Popoiti and then start shoving some signals from the encoder down the radio link to see what happens.