| Popis: |
A new decoder is being developed by the Jet Propulsion Laboratory for NASA's Deep Space Network. This unit will decode the new turbo codes, which have recently been approved by the Consultative Committee for Space Data Systems (CCSDS). Turbo codes provide up to 0.8 dB improvement in E/sub b//N/sub 0/ over the current best codes used by deep space missions. The new decoder is being implemented in software running on commercial DSP chips, removing the need to design complicated and expensive hardware as was the case with the previous generation of codes. The decoder will time-tag the data frames, perform frame synchronization in the symbol domain (as opposed to the current bit domain synchronization), decode the turbo coded frames, and output the decoded bits in the CCSDS Standard Formatted Data Units format. The decoder is initially designed to operate up to 365 kbps, but will increase in rate as DSP clock rates increase. The implementation will go operational in October, 2003. |
