Abstract: Devices for aiding installation of control lines in suspended ceiling systems; each comprising a flat base portion, a squared side having a paralleled horizontal groove formed therein to receive a portion of wall angle molding used with grids at 90° angles in relation to walls, an angled side having a paralleled horizontal groove formed therein to receive a portion of wall angle molding used with grids at 45° angles in relation to walls, threaded holes formed through top portion, first and second means for temporarily attaching devices onto wall angle moldings, means for restricting movement of main tees and cross tees which together allow a control line be wrapped around horizontal grooves, pulled taut, and wrapped around first or second means for temporarily attaching said devices onto wall angle moldings to lock said control line taut.

Abstract: In a helical scan magnetic tape recorder, a rotary magnetic head scanner includes odd and even azimuth data reproduce heads and odd and even azimuth sense heads on the head wheel to effect automatic tracking. The odd and even azimuth sense heads establish a tracking error signal when reproduced signal envelopes are not equal. The error signal is used to control a capstan servo to maintain correct data head-to-track positioning.

Abstract: A helical scan magnetic tape recorder includes a rotary scanner having magnetic heads which record and reproduce data on slant tracks of magnetic tape helically transported about the rotary scanner. Low frequency tones representing a time code or other digital information are recorded by the data heads of the rotary head scanner in the same lateral location such as preamble segments of the data tracks. The recorded time code is recovered by means of a stationary magnetic head. The recovered low frequency tones are converted into digital information such as a digital time code which provides tape location information for editing or searching purposes as well as other auxiliary information such as recorder serial number, data rate codes, etc.