Accession Number : ADA116401

Title :   Reliability and Maintainability Evaluation of the Mode S System.

Descriptive Note : Final rept. Oct 78-May 80,


Personal Author(s) : Moss,Arthur R ; Apostolakis,George C

PDF Url : ADA116401

Report Date : May 1982

Pagination or Media Count : 43

Abstract : A reliability and maintainability evaluation was performed on Mode S (formerly the Discrete Address Beacon System (DABS)) engineering model sensors located at the Federal Aviation Administration Technical Center, Elwood, and Clementon, New Jersey. The observed system mean-time-between-failure (MTBF) based on chargeable failures ranged from 767 hours for the Technical Center sensor to 1,913 hours for the Elwood site sensor. The preponderance of failures at the Technical Center sensor probably occured because the system was stressed to a greater extent than the other two sites. Elements which failed and caused system outrage at all three sites were the transmitter, processor, and WWVB receiver. The transmitter and processor, which are single-string elements, were found to be the weak points in the system reliability design. The measured failure rates for these two elements, in particular the processor, exceeded the predicted values. Problem areas were: inadequate radio station WWVB receiver output; damage to wire-wrap pin in the computer ensembles caused by power cables rubbing against them, excessive failures in the traveling wave tube associated circuitry, failure of cooling fans, susceptibility of the sensor to lightning damage, and loose and dirty printed circuit board contacts. (Author)

Descriptors :   *Discrete address beacon systems, *Reliability, *Maintainability, Printed circuit boards, Test and evaluation, Sites, Failure, Electric cables, Cooling fans

Subject Categories : Non-radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE