A vector tree correlator correlates over received data spread at differing spreading
rates or, over differing lengths of spreading sequence. When the maximum length
sequence has a length N that is an integer power of 2, or 2M, then the
vector tree correlator is formed from M levels. Level (1) is formed of add/subtract
logic units, and Level (2) through Level (M) are formed of adders. Add/subtract
logic units each receive a pair of received signal samples and combines the received
signal samples based on a control signal input. The control signal input is derived
from the locally generated spreading sequence. The output of the adder at the top
of the tree is the result of the length N correlation, while output tap points
at different levels of the tree each provide a correlation for one of the different
spreading rates of length 2m, 1
