Single-station meteor shower detections produce distributions of shower meteor speeds that can be used to estimate the velocity of shower meteoroids entering the atmosphere. Meteor shower velocity is used to calculate the orbital parameters of the debris streams that are responsible for meteor showers, so it is important to understand the accuracy of shower velocity estimation techniques. An analysis of the distribution of speeds of shower meteors can also be used to assess the precision and accuracy of the speed estimation technique used. The velocity estimates of 522 shower detections obtained during a survey of 33 MHz meteor radar data from 2006 to 2007 have been compared to velocity values in the IAU data base and used to assess the performance of the Fresnel transform method of speed estimation. It is shown that the estimates for high-velocity showers are strongly influenced by the angle-of-entry of the meteors due to the removal of early-stage ablation meteors in shallow trajectories by the underdense echo high-altitude cut-off phenomenon.