Doppler speed measurement amplitude breakdown error correcting circuit - uses opposed up-down counters triggered by null crossings

摘要

A circuit for reduction of measurement errors in a monitoring system and/or control system for movement and/or speed of rail and other traffic using Doppler measurement techniques is partic. suitable for shunting operations where automatic braking control is used. The circuit relates to errors resulting from short duration Doppler wave amplitude breakdowns lasting up to several Doppler periods. - A signal is generated to indicate the occurrence of a break-down. Two 180 degree phase-shifted signals with the instantaneous Doppler frequency are connected to separate up-down counter control inputs. The counters are always couting in opposite directions and are reversed by a null crossing. Attainment of a certain number of counts causes the interrupt signal generation.