A television system performs beam convergence in video displays. The system is implemented through one or more convergence sensors, which are exposed to two distinct convergence test patterns. The output signals from the sensors when exposed to the two test patterns are used in beam convergence calculations. The test patterns are selected to reduce the dynamic range requirement for an A/D converter in the television system supplied with the sensor output signals. A low-pass filter circuit with selectable characteristics is also used to reduce the dynamic range requirement.