Weighted-sum processing method and apparatus for decoding optical signals

DETAILED DESCRIPTION It is thereafter an object of the present invention to provide a more reliable method and apparatus for detecting and decoding optical signals.
It is a further object of the invention to provide a method and apparatus for reliably detecting low level signals by increasing the gain of the detection while simultaneously decreasing the bit error rate.
These and other objects are provided, according to the present invention, by a method and associated apparatus for decoding an optical signal which appropriately weights the respective noise portions of the two phase segments generated by the photodetector, such as an APD, such that the optical signal can be reliably decoded.
In operation, the photodetector detects an optical signal having a light portion and a dark portion.
The photodetector then generates an electrical pulse in response to the optical signal.
The electrical pulse has two phase segments, namely, one segment corresponding to the light portion of the optical signal and another phase segment corresponding to the dark portion of the optical signal.
Each phase segment includes respective signal and noise portions.
According to the present invention, a signal weighting factor is determined, such as by a signal weighting factor determining means, based upon the respective noise portions of the two-phase segments.
Thereafter, at least one phase segment is weighted by the signal weighting factor.
A decoder can then identify the optical signal based upon the first and second phase segments as weighted by the signal weighting factor.
The signal weighting factor determining means preferably includes power determining means for determining the power of the respective noise portions of the two phase segments.
Based upon the power of the respective noise portions, the signal weighting factor can be determined such that the multiplicative product of the signal weighting factor and the power of the noise portion of one phase segment equals the power of the noise portion of the other phase segment