e probes can be transmitted back to Earth. The advantages are many; including the fact that Shannon's theorem can inform the telecommunications rate even when the received SNR is very small. Error control coding techniques are also used extensively for different space telecommunications applications including telem- etry and control signalling. For example the Voyager 2 space probe takes 800x800 pixel digital photos, and uses 8 bits to quantise each pixel. However since most of the picture is of black space, the difference between adjacent pixels is coded resulting in up to 60% image compression. The error control codes used in the Voyager probe is a concatenation of convolutional (2,1,7) and block codes - Reed-Solomon code (255,223) for the state of the art in error correction at the time and within 2 dB of the Shannon limit [8, 9]. Case Study Questions Why is it difficult to transmit analogue photos from space probes? What are the advantages of digital technology for space telecommunications? How does FEC coding assist with system link budgeting? How did the FEC techniques help with the overall BLER performance? What are the business benefits of source coding and channel coding in space telecommunications? NASA (public domain): https://commons.wikimedia.org/wiki/File%3AMariner_3_and_4.jpg. Error Control Coding Turbo Codes Another class of codes used in the 3G wireless standards are turbo codes. Turbo codes are an iterative class of codes based on convolutional codes, invented by Berrou, Glavieux and Thitimajshima and first presented in 1993 [10]. The code's near-Shannon limit performance created a sensation and soon iterative decoding became the focus of FEC coding research. The name 'turbo' was used since the operation of the decoder is somewhat similar to a turbo engine, which takes exhaust energy in and feeds it back into the engine. In the same way two parallel turbo decoders take turns to improve the reliability of a received bit, and pass it bet- ween each other to further improve on the reliability. The 