Display Factors Affecting The Visibility of Information on a Simulated Passive Sonar Display.
DEFENCE AND CIVIL INST OF ENVIRONMENTAL MEDICINE DOWNSVIEW (ONTARIO)
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With current sonar technology the operator must handle large quantities of data. The primary medium for displaying these data is the CRT. Because of the limited space available on the CRT, the operator must scan multiple pages of data rapidly if he or she is to monitor all of the information. Thus, signal visibility is critical. To ensure good visibility, it is necessary to understand the impact of display characteristics on the detectability of signals on a display. This study examined the effect on signal detection of rotating a frequency-time-intensity FTI display 90 degrees so that the signal lines fell along the scan lines of the CRT. Currently, the signal lines on an FTI display are perpendicular to the CRT raster. The effect of having signal lines fall along the scan lines of the CRT was assessed on both a monochrome and a multichrome monitor to see if the effects were similar on both types of monitors. In addition, performance was assessed in two conditions in which the visual image was potentially degraded. The degraded displays resulted from the reduction in average luminance of the monitor that frequently happens over time and the use of long video cables between the computer monitor and processor. In all the conditions, subjects had to detect signals of varying strength presented on a simulated dynamic FTI display. Signals were added to a FTI display that was updated every 5 seconds. There was a clear advantage, on both types of monitors, to using a display format in which the signals fell along the scan lines of the CRT. Between 12 and 18 more signal lines were detected when the FTI display was rotated 90 degrees. Degradation of the output had no perceptible effect on detection of the signal lines.
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