Synchronizing Signal Detector
Original Publication Date: 1980-Jan-01
Included in the Prior Art Database: 2005-Feb-13
Shown in the figure is a detection circuit capable of detecting the V29 CCITT Recommendation synchronizing signals. These synchronizing signals begin with a synchronizing pattern which consists of alternations between two signal elements for 128 symbol intervals, and have a spectrum comprising three components: one at the carrier frequency f(c) and two at Nyquist frequencies f(1) = f(c) - 1/2 T and f(2) = f (c) + 1/2 T, T being the symbol interval. The detection circuit performs four different tasks: - estimation of the signal energy Eny at Nyquist frequencies f(1) and f(2); - estimation of the signal energy Ec at carrier frequency f(c); - estimation of the total signal energy Et; and - estimation of the noise energy En.