TECHNIQUES FOR SYNCHRONIZING THERMAL ARRAY CHART RECORDERS TO VIDEO

Abstract

Video tape is becoming more and more popular for storing and analyzing missions. Video tape is inexpensive, it can hold a two hour test, and it can be edited and manipulated by easily available consumer electronics equipment. Standard technology allows each frame to be time stamped with SMPTE code, so that any point in the mission can be displayed on a CRT. To further correlate data from multiple acquisition systems, the SMPTE code can be derived from IRIG using commercially available code converters. Unfortunately, acquiring and storing analog data has not been so easy. Typically, analog signals from various sensors are coded, transmitted, decoded and sent to a chart recorder. Since chart recorders cannot normally store an entire mission internally, or time stamp each data value, it is very difficult for an analyst to accurately correlate analog data to an individual video frame. Normally the only method is to note the time stamp on the video frame and unroll the chart to the appropriate second or minute, depending on the code used, noted in the margin, and estimate the frame location as a percentage of the time code period. This is very inconvenient if the telemetrist is trying to establish an on-line data retreival system. To make matters worse, the methods of presentation are very different, chart paper as opposed to a CRT, and require the analyst to shift focus constantly. For these reasons, many telemetry stations do not currently have a workable plan to integrate analog and video subsystems even though it is now generally agreed that such integration is ultimately desirable.