Delay Line Combination (DLC) receivers have been proposed for time hopping impulse radio ultra wideband (TH-IRUWB) systems by Wen and Hsu. In that study, we also presented a non-data aided synchronization algorithm designated as ”timing with delay line combination” (TDLC) algorithm. Although channel estimation is unnecessary for the DLC receivers, the system performance is affected by the setting of the integration window length (Tw). By tracking the variance of estimated timing offsets of the TDLC algorithm for each Tw setting, it’s found that the minimum variance is obtained at a best Tw setting. However,the best Tw setting is various in different channel environments. To optimize the system performance, for example mean square error (MSE) and bit error rate (BER) of the DLC receivers,we propose a non-data aided adaptive algorithm named ”leastvariance” (LV) adaptive algorithm to estimate the best Tw settingfor all channel environments.