The invention relates to a method of automatically tuning a loop-filter of a phase locked loop. A boom member mounted on the carriage unit is operable for selected pivotal movement relative to the carriage unit, and a plane generally parallel to the boom member’s longitudinal axis, about a generally horizontal pivot axis oriented transverse to the direction of shifting of the carriage unit along the frame structure. A second signal combiner coupled with the delayed signal terminal and the output employs the output signal and the second delayed signal to present an error signal at a first error terminal. There is a cage portion that has one open end and one enclosed end. The luminance control circuit further may also be used to discontinue varying the luminance levels of the video signal when the motion detection output signal indicates that the video signal includes a still image. The system can display metadata for user modification.