Patent ID: 6259086
Filing Date: 2001-07-10
Classification: H04B

Abstract:
A method for detection of a light signal and obtaining error signals for correction of alignment errors of said light signal, comprising the following steps:detecting said light signal by means of a plurality of photosensitive detection means with outputs giving photo currents which are fed into a transimpedence amplifier in which said photo currents are converted into output voltages x.sub.1, x.sub.2, y.sub.1, y.sub.2 ;distributing said output voltages via a distributor network to a first difference channel block in which a first difference signal x.sub.1 -x.sub.2, is generated, to a second difference channel block in which a second difference signal y.sub.1 -y.sub.2 is generated and to sum channel block in which a sum signal x.sub.1 +x.sub.2 +y.sub.1 +y.sub.2 is generated;performing in said difference channel blocks either a multiplication of said first and second difference signals with said sum signal or a phase-sensitive demodulation of said first and second difference signals with said sum signal as reference; andwherein said difference channel blocks each have an output providing an error signal approximately equal to said difference signals, and wherein said error signals are, narrow-band error signals for correction of alignment errors of said light signal.