Patent ID: 7397869

Claim:
A process for providing pilot aided phase recovery of a carrier of an input digital signal Zk, said signal Zk comprising signal fields comprised of L s symbols, namely a block of L P pilot symbols Z P (k) and a data field of L s −L P data symbols Z d (k) , and characterized in that it comprises for each signal field: calculating an unwrapped pilot phase estimate {circumflex over (θ)} f (P) (l); initiating with {circumflex over (θ)} f (P) (l) a first digital phase locked loop (DPLL F ) implementing a phase estimate algorithm and calculating a forward phase trajectory {circumflex over (θ)} F (k) from the data symbols Z d (k) of the data field, k s being an integer varying between 1 and L s −L P over said data field, said forward phase trajectory {circumflex over (θ)} F (P) (l) being comprised of L s −L P forward phase estimates {circumflex over (θ)} F (k s ); and initiating with {circumflex over (θ)} (P) f (l+1) a second digital phase locked loop (DPLL B ), implementing a phase estimate algorithm and calculating a backward phase trajectory {circumflex over (θ)} B (k s ) from the data symbol signals Z d (k), k s varying between L s −L P and 1 over said data field (l), said backward phase trajectory {circumflex over (θ)} B (k s ) being comprised of L s −L P backward phase estimates {circumflex over (θ)} B (k s ); from said phase trajectories calculating a phase correction (e −j{circumflex over (θ)}(ks) ); and multiplying said phase correction e −j{circumflex over (θ)}(ks) with said input signal Zk to generate a phase corrected input signal for the data symbols, and wherein: {circumflex over (θ)} (p) f ( l )={circumflex over (θ)} (p) f ( l −1)+α SAW└{circumflex over (θ)} (p) ( l )−{circumflex over (θ)} (p) f ( l −1)┘ where SAW [Φ]≡[Φ] −π +π is a sawtooth nonlinearity that reduces Φ to the interval [−π, π) and α is a parameter in the range 0<α≦1, and {circumflex over (θ)} (P) (l) is a phase estimate in the block of Lp pilot symbol of said pilot field (l).