A system for determining a signal recovery configuration for upstream transmission of bursts (10;11;12;13) from optical network units (2;3;4;5), abbreviated ONUs, to an optical line termination (6;7), abbreviated OLT, in a passive optical network , abbreviated PON, wherein said system comprises: - means configured to receive an upstream burst from one of said ONUs , wherein said upstream burst is distorted by upstream transmission impairments; - means configured to detect a received pattern in said upstream burst , wherein a header of said upstream burst comprises an identifier and a preamble comprising said received pattern ; - means configured to determine a pattern identification descriptor for said ONU indicative for a level of difference between said received pattern and a predefined pattern corresponding to said received pattern ; - means configured to store a predetermined correspondence between predefined patterns and signal recovery configurations in a predetermined look-up table comprising predefined pattern identification descriptors ; and wherein to each predefined pattern identification descriptor corresponds a signal recovery configuration ; - means configured to access said predetermined look-up table ; - means configured to match said pattern identification descriptor to one of said predefined pattern identification descriptors from said predetermined look-up table ; and - means configured to look-up in said look-up table a signal recovery configuration corresponding to said predefined pattern identification descriptor matching said pattern identification descriptor , thereby determining a signal recovery configuration for said upstream burst corresponding to said predefined pattern corresponding to said received pattern of said upstream burst , thereby determining a signal recovery configuration for said upstream burst . - means configured to receive an upstream burst from one of said ONUs , wherein said upstream burst is distorted by upstream transmission impairments; - means configured to detect a received pattern in said upstream burst , wherein a header of said upstream burst comprises an identifier and a preamble comprising said received pattern ; - means configured to determine a pattern identification descriptor for said ONU indicative for a level of difference between said received pattern and a predefined pattern corresponding to said received pattern ; - means configured to store a predetermined correspondence between predefined patterns and signal recovery configurations in a predetermined look-up table comprising predefined pattern identification descriptors ; and wherein to each predefined pattern identification descriptor corresponds a signal recovery configuration ; - means configured to access said predetermined look-up table ; - means configured to match said pattern identification descriptor to one of said predefined pattern identification descriptors from said predetermined look-up table ; and - means configured to look-up in said look-up table a signal recovery configuration corresponding to said predefined pattern identification descriptor matching said pattern identification descriptor , thereby determining a signal recovery configuration for said upstream burst corresponding to said predefined pattern corresponding to said received pattern of said upstream burst , thereby determining a signal recovery configuration for said upstream burst . <EOS>