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In the semi-rural idyll of Ascot, the Ludlam family has come up with a set-top box with a difference.
Promise TV records programmes from terrestrial digital Freeview, but unlike other systems, it doesn't rely on the viewer selecting shows to record. Instead, it records everything broadcast over seven days: every show transmitted on all 40-odd radio and TV channels, without pause. Recordings are grouped by category, as well as time or date, so it's like a constantly renewed watch-on-demand service.
The family, led by husband-and-wife team Richard and Kate Ludlam, handle everything to do with the Promise TV system themselves, including case design and prototype production. Sons Dominic and Christian Ludlam take care of the software and hardware design, respectively.
One of the trickier design problems on the Promise TV was the tuner board, the Ludlams told ZDNet UK. With up to six multiplexes to receive simultaneously, the incoming signal needs to be to split between six radio receivers, and the six 24Mbps decoded data streams need to be continually sent to the recording circuitry.
Radio frequency signals in particular are very sensitive to board layout, digitally generated noise and cross-talk between circuits, which makes design something of an art. Here, each receiver has three chips and a couple of filters, effectively producing a 144Mbps one-way wireless network card that works over many tens of miles.
Image credit: Rupert Goodwins/ZDNet UK