ANALYSIS AND MODIFICATION OF RVR EQUIPMENT FOR RVR VALUES 500 FEET AND ABOVE.

A rationale of the design criteria and choices of the present RVR system, reportings based on atmospheric transmittance measured over a 500 foot path, is presented. Modifications to existing equipment for low RVR reporting on three different schedules are described. Each of the three reporting modes are based on transmittance measurements over a 250 foot path. Reportings are from 600 feet in 200 and 500 foot increments, from 500 feet in 100 and 200 foot increments and from 500 feet in 100, 200 and 500 foot increments. Cost reductions that could be effected in the purchase of new equipment as a result of eliminating one or two light settings, LS3 and LS4, are revealed. RVR computer modifications are discussed for an end-to-end transmissometer configuration. An operational analysis of the RVR computer system reveals three areas requiring improvement additional circuitry is required to provide more reliable operation of the Receiver-Decoder over noisy signal lines a design change is needed to eliminate the possibility of serious damage to the computer by erroneous insertion of interconnecting cables, and improved fabrication methods should be applied to the etched circuit relay board of the Signal Data Converter. Various modes of system operation enhancement are discussed oral RVR reporting, data communication methods, and RVR testing capability expansion. Author