Control system for the Fermilab trombone notch filter

The authors describe a servo system designed to control the position of a trombone notch filter. The filter resonates at 295 kHz in the debuncher and 628 kHz in the accumulator with a 10-p.p.m. accuracy. The trombone, moved by a step motor, can be positioned manually, sending commands from a host computer, using a dump terminal, or operating automatically in servo mode to minimize the error. The electronics was designed using high-level-integration erasable PLDs (programmable logic devices), simplifying future upgrades. High-level development tools were utilized to program and test these devices, minimizing error sources during the design stage