Seat belt 1967, Volvo started to install lap belts in the rear seats. In 1972, Volvo upgraded the rear seat belts to a three-point belt. In crashes, unbelted rear passengers increase the risk of belted front seat occupants' death by nearly five times. As with adult drivers and passengers, the advent of seat belts was accompanied by calls for their use by child occupants, including legislation requiring such use. Generally children using adult seat belts suffer significantly lower injury risk when compared to non-buckled children. The UK extended compulsory seatbelt wearing to child passengers under the age of 14 in 1989. It
Convolutional code least since the Voyager program has a constraint length "k" of 7 and a rate "r" of 1/2. Puncturing is a technique used to make a "m"/"n" rate code from a "basic" low-rate (e.g., 1/"n") code. It is reached by deletion of some bits in the encoder output. Bits are deleted according to a "puncturing matrix". The following puncturing matrices are the most frequently used: For example, if we want to make a code with rate 2/3 using the appropriate matrix from the above table, we should take a basic encoder output and transmit every first bit from the first