Preset Control Research Articles

VIR II System

The quality of color reproduction in color television receivers has often suffered due to the misadjustment of chroma level and tint controls by the customer. To give some help to the customer, several schemes have been introduced such as automatic chroma level, automatic tint, and factory preset controls, These systems are widely used, but do not solve the problems caused by chroma level or subcarrier phase differences between stations or control voltage drift during warm-up period. Moreover, factory preset controls are subject to drift from their original setting due to component aging and eventually should be set again, which requires a service call. Therefore, a better system which is not subject to these problems become desirable. In October, 1975, after several years of testing by the broadcasting industry and the EIA, the FCC designated the 19th line of each field of video information as reserved for a specific Vertical Interval Reference (VIR) signal. The signal itself simply consists of a chroma reference, a luminance reference, and a black level reference as shown in Fig. 1. When the chrominance reference and black level reference are equal in amplitude at the receiver's R-Y output, chroma phase (tint) conforms to that of the transmitted reference signal. Likewise, by maintaining proper amplitude relationship between the B-Y output and the luminance signal, chroma level can be matched to the reference signal. The use of this VIR signal has finally provided the color television receivers with the means for truly automatic chroma level and tint reception.

Design and Performance of an Automatic Control System for Fastener Tightening

Methods of controlling the tightness of bolted assemblies by presetting the torque or bolt rotation are reviewed. It is shown that these produce either inaccurate clamp loads or excessive elongation of the fastener. As a result the tightening operation is often the weakest link in obtaining a reliable assembly. The development of a system of tightening control that overcomes these problems is described. It operates by sensing the gradient of the torque-rotation characteristic, thus detecting the yield point of the fastener. In principle it requires no preset control torques or rotation angles. Comparative results show that the system increases bolt clamp loads and reduces their scatter very significantly.

Machines for physicomechanical testing of polymeric materials

Two tensile-testing machines are described for physicomechanical tests of polymeric materials with deformation up to 100 and 1,000% in which the conditions of deformation are assigned directly to the measurement base of the specimen by using an automatically regulated electric drive, ensuring parity of the measured quantity (force, elongation, or stress) with the requisite preset functional controller.

A lesion generator for controlled radio frequency lesions in stereotaxic surgery

A short discussion of the requirements for the creation of controlled lesions in brain tissue is followed by a description of a suitable instrument using the radio frequency heating method. The instrument has monitoring facilities making it suitable for research, and incorporates protection circuits which make it safe under extreme conditions of misuse. Testing and checking are quickly and easily carried out in the theatre, and urgent maintenance is provided for by the use of plug-in circuits. Variations in the electrical characteristics of different probes are accommodated by preset calibration controls.

Flexibility and Preset Control Boards

Flexibility and Preset Control Boards